DETECTOR FOR OPTICALLY DETECTING AT LEAST ONE OBJECT
20170074652 ยท 2017-03-16
Assignee
Inventors
- Robert Send (Karlsruhe, DE)
- Ingmar BRUDER (Neuleiningen, DE)
- Stephan IRLE (Siegen, DE)
- Erwin THIEL (Siegen, DE)
Cpc classification
G06F3/0421
PHYSICS
G06F3/017
PHYSICS
G01J1/0266
PHYSICS
G01S17/86
PHYSICS
G01S17/894
PHYSICS
G06F3/0346
PHYSICS
G01J3/0289
PHYSICS
G06F3/0423
PHYSICS
International classification
Abstract
A detector for determining a position of at least one object, where the detector includes: at least one optical sensor, where the optical sensor has at least one sensor region, where the optical sensor is designed to generate at least one sensor signal in a manner dependent on an illumination of the sensor region by illumination light traveling from the object to the detector; at least one beam-splitting device, where the beam-splitting device is adapted to split the illumination light in at least two separate light beams, where each light beam travels on a light path to the optical sensor; at least one modulation device for modulating the illumination light, where the at least one modulation device is arranged on one of the at least two light paths; and at least one evaluation device, where the evaluation device is designed to generate at least one item of information from the at least one sensor signal.
Claims
1. A detector (110) for determining a position and/or a color of at least one object (112), comprising: at least one optical sensor (114), wherein the optical sensor (114) has at least one sensor region (136), wherein the optical sensor (114) is designed to generate at least one sensor signal in a manner dependent on an illumination of the sensor region (136) by illumination light traveling from the object (112) to the detector (110), at least one beam-splitting device (129), wherein the beam-splitting device (129) is adapted to split the illumination light in at least two separate light beams (139), wherein each light beam travels on a light path to the optical sensor (114), at least one modulation device (137) for modulating the illumination light, wherein the at least one modulation device (137) is arranged on one of the at least two light paths, at least one evaluation device (142), wherein the evaluation device (142) is designed to generate at least one item of information from the at least one sensor signal (114), in particular at least one item of information about the distance and/or the color of the object (112).
2. The detector (110) according to the preceding claim, wherein at least one modulation device (137) is arranged on each of the at least two light paths.
3. The detector (110) according to any one of the preceding claims, wherein the modulation device (137) is adapted to periodically modulate an amplitude of the illumination light.
4. The detector (110) according to any of the preceding claims, wherein the optical sensor (114) is designed in such a way that the sensor signal, given the same total power of the illumination, is dependent on a modulation frequency of a modulation of the illumination.
5. The detector (110) according to any of the preceding claims, wherein the beam-splitting device (129) is selected from the group consisting of: a mirror (131), a semitransparent mirror (133); a mirror (131) or a semi-transparent mirror (133) reflecting only within a specific spectral region; a prism (141), a dichroic prism, a trichroic prism (143), and a multichroic prism; a beam splitter cube; a wavelength-sensitive switch (145).
6. The detector (110) according to any of the preceding claims, wherein the beam-splitting device (129) is a movable reflective element adapted to be adjusted to at least two different positions, wherein, in the at least two different positions, the illumination light is reflected into different directions, wherein, in each different position, the reflected illumination light form the separate light beam.
7. The detector (110) according to any one of the preceding claims, wherein the evaluation device (142) is adapted to generate the at least one item of information on a color of the object (112) by evaluating which of the at least one light beams (138) impinges the at least one optical sensor (114) being sensitive to the color of the object (112).
8. The detector (110) according to any of the preceding claims, wherein the optical sensor (114) further comprises a longitudinal optical sensor (132), wherein the longitudinal sensor signal, given the same total power of the illumination, is dependent on a beam cross-section of the light beam (138) in the sensor region (136), in particular on a beam cross-section of the light beam (138) in the sensor region.
9. The detector (110) according to the preceding claim, wherein the longitudinal optical sensor (132) comprises at least one dye-sensitized solar cell and/or an inorganic diode.
10. The detector (110) according to any one of the two preceding claims, wherein the evaluation device (142) is designed to generate the at least one item of information on the longitudinal position of the object (112) from at least one predefined relationship between the geometry of the illumination and a relative positioning of the object (112) with respect to the detector (110).
11. The detector (110) according to the preceding claim, wherein the evaluation device (142) is adapted to generate the at least one item of information on the longitudinal position of the object (112) by determining a diameter of the light beam (138) from the at least one longitudinal sensor signal.
12. The detector (110) according to any of the four preceding claims, wherein the detector (110) has a plurality of longitudinal optical sensors (132), wherein the longitudinal optical sensors (132) are stacked.
13. The detector (110) according to the preceding claim, wherein the longitudinal optical sensors (132) are arranged such that a light beam (138) from the object (112) illuminates all longitudinal optical sensors (132), wherein at least one longitudinal sensor signal is generated by each longitudinal optical sensor (132), wherein the evaluation device (142) is adapted to normalize the longitudinal sensor signals and to generate the information on the longitudinal position of the object (112) independent from an intensity of the light beam (138).
14. The detector (110) according to any one of the preceding claims, wherein the optical sensor (114) further comprises at least one transversal optical sensor (130), the transversal optical sensor (130) being adapted to determine a transversal position of at least one light beam (138) traveling from the object (112) to the detector (110), the transversal position being a position in at least one dimension perpendicular an optical axis of the detector (110), the transversal optical sensor being adapted to generate at least one transversal sensor signal.
15. The detector according to the preceding claim, wherein the transversal optical sensor comprises at least one semiconductor detector, in particular an organic semiconductor detector comprising at least one organic material, preferably an organic solar cell and particularly preferably a dye solar cell or dye-sensitized solar cell, more particular a solid dye solar cell or a solid dye-sensitized solar cell, and/or, in particular an inorganic semiconductor detector, preferably an intransparent inorganic diode, more preferably comprising at least one of silicon, germanium, or gallium arsenide.
16. The detector (110) according to any of the two preceding claims, wherein the transversal optical sensor (130) and the longitudinal optical sensor (132) are stacked along the optical axis such that the light beam (138) travelling along the optical axis (116) both impinges on the transversal optical sensor (130) and on the longitudinal optical sensor (132).
17. The detector (110) according to any of the three preceding claims, wherein the evaluation device (142) is designed to generate at least one item of information on a transversal position of the object (112) by evaluating the transversal sensor signal and to generate at least one item of information on a longitudinal position of the object (112) by evaluating the longitudinal sensor signal.
18. A human-machine interface (196) for exchanging at least one item of information between a user (200) and a machine, the human-machine interface (196) comprising at least one detector (110) according to any of the preceding claims relating to a detector (110), wherein the human-machine interface (196) is designed to generate at least one item of geometrical information of the user (200) by means of the detector (110) wherein the human-machine interface (196) is designed to assign to the geometrical information at least one item of information.
19. An entertainment device (198) for carrying out at least one entertainment function, wherein the entertainment device (198) comprises at least one human-machine interface (196) according to any of the preceding claims referring to a human-machine interface (196), wherein the entertainment device (198) is designed to enable at least one item of information to be input by a player by means of the human-machine interface (196), wherein the entertainment device (198) is designed to vary the entertainment function in accordance with the information.
20. A tracking system (199) for tracking the position of at least one movable object (112), the tracking system (199) comprising at least one detector (110) according to any of the preceding claims referring to a detector (110), the tracking system (199) further comprising at least one track controller (201), wherein the track controller (201) is adapted to track a series of positions of the object (112), each position comprising at least one item of information on a transversal position of the object (112) at a specific point in time and at least one item of information on a longitudinal position of the object (112) at a specific point in time.
21. A scanning system for determining at least one position of at least one object (112), the scanning system comprising at least one detector (110) according to any of the preceding claims relating to a detector (110), the scanning system further comprising at least one illumination source adapted to emit at least one light beam configured for an illumination of at least one dot located at at least one surface of the at least one object (112), wherein the scanning system is designed to generate at least one item of information about the distance between the at least one dot and the scanning system by using the at least one detector (110).
22. A camera for imaging at least one object (112), the camera comprising at least one detector (110) according to any one of the preceding claims referring to a detector (110).
23. A method for determining a position and/or a color of at least one object (112), wherein at least one optical sensor (114) is used, wherein the optical sensor (114) has at least one sensor region (136), wherein the optical sensor (114) is designed to generate at least one sensor signal in a manner dependent on an illumination of the sensor region (136) by the illumination light traveling from the object (112) to the detector (110), wherein at least one beam-splitting device (129) is used, wherein the beam-splitting device (129) is adapted to split the illumination light in at least two separate light beams (138), wherein each light beam travels on a light path to the optical sensor (114), wherein at least one modulation device (137) for modulating the illumination light is used, wherein the at least one modulation device (137) is arranged on one of the at least two light paths, wherein at least one evaluation device (142) is used, wherein the evaluation device (142) is designed to generate at least one item of information from the at least one sensor signal, in particular at least one item of information about the position and/or the color of the object (112).
24. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use, selected from the group consisting of: a distance measurement, in particular in traffic technology; a position measurement, in particular in traffic technology; a tracking application, in particular in traffic technology.
25. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use as an entertainment application.
26. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use as a camera, in particular in a security application.
27. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use as a human-machine interface (196) application.
28. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use as a mapping application, in particular for generating maps of at least one space.
29. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use in automated machine processes, selected from the group consisting of: a distance measurement; a position measurement; a tracking application.
30. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use in high-precision metrology, in particular in analytics.
31. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use in modeling of manufacturing parts.
32. The use of a detector (110) according to any of the preceding claims relating to a detector (110), for a purpose of use in medical operations, in particular in endoscopic methods.
Description
BRIEF DESCRIPTION OF THE FIGURES
[0427] Further optional details and features of the invention are evident from the description of preferred exemplary embodiments which follows in conjunction with the dependent claims. In this context, the particular features may be implemented alone or with several in combination. The invention is not restricted to the exemplary embodiments. The exemplary embodiments are shown schematically in the figures. Identical reference numerals in the individual figures refer to identical elements or elements with identical function, or elements which correspond to one another with regard to their functions.
[0428] Specifically, in the figures:
[0429]
[0430]
[0431]
[0432]
[0433]
[0434]
[0435]
[0436]
[0437]
EXEMPLARY EMBODIMENTS
Detector
[0438]
[0439] The detector 110 comprises a plurality of optical sensors 114, which, in the specific embodiment, are all stacked along an optical axis 116 of the detector 110. Specifically, the optical axis 116 may be an axis of symmetry and/or rotation of the setup of the optical sensors 114. The optical sensors 114 may be located inside a housing 118 of the detector 110. Further, at least one transfer device 120 may be comprised, such as one or more optical systems, preferably comprising one or more lenses 122. An opening 124 in the housing 118, which, preferably, is located concentrically with regard to the optical axis 116, preferably defines a direction of view 126 of the detector 110. A coordinate system 128 may be defined, in which a direction parallel or antiparallel to the optical axis 116 is defined as a longitudinal direction, whereas directions perpendicular to the optical axis 116 may be defined as transversal directions. In the coordinate system 128, symbolically depicted in
[0440] Particularly for determining the color of the object 112, the detector 110 according to the invention further comprises a beam-splitting device 129, wherein the beam-splitting device 129 is adapted to split the light beam travelling from the object 112 to the detector 110 in this particular example into three separate light beams 139. Herein, all of the three separate light beams 139 are, furthermore, re-combined into a single light beam 138 prior to passing through the opening 124 of the housing 118 where the optical sensors 114 are located. However, the housing 118 may otherwise be designed in a manner that it additionally comprises the beam-splitting device 129.
[0441] In this particular embodiment, the light beam first travels through at least one transfer device 120, such as one or more optical systems, preferably one or more lenses 122, until it impinges the beam-splitting device 129 which comprises three mirrors 131 in a consecutive arrangement adapted for splitting the single light beam 138 into three separate light beams 139. Herein, two semi-transparent mirrors 133, i.e. mirrors adapted to reflect the impinging light beam only as long as it exhibits a wavelength within a specific spectral region whereas a light beam exhibiting a wavelength outside the specific spectral region will pass, and an intransparent mirror 135 provide for a splitting of the impinging light beam 138 into three separate light beams 139.
[0442] As already described above, for re-combining the three separate light beams 139 three additional mirrors 131, i.e. an intransparent mirror 135 and two semi-transparent mirrors 133, are employed in a consecutive arrangement. This arrangement is selected particularly due to the consideration that re-combining the three separate light beams 139 into a single light beam may be viewed as splitting the inverted light beam travelling into the inverted direction into separate light beams.
[0443] Particularly for being able to distinguish between at least three different colors of the object 112, the detector 110 according to the invention further comprises at least one modulation device 137 for modulating the light in at least one of the separate light beams 139. In the exemplary embodiment as depicted in
[0444] In this exemplary embodiment, the optical sensors 114 comprise at least one transversal optical sensor 130 and a plurality of longitudinal optical sensors 132. The longitudinal optical sensors 132 form a longitudinal optical sensor stack 134. In the embodiment shown in
[0445] The transversal optical sensor 132 comprises a sensor region 136, which, preferably, is transparent to a light beam 138 travelling from the object 112 to the detector 110. The transversal optical sensor 130 is adapted to determine a transversal position of the light beam 138 in one or more transversal directions, such as in direction x and/or in direction y. Therein, embodiments are feasible in which a transversal position in only one transversal direction is determined, embodiments in which transversal positions in more than one transversal direction are determined by one and the same transversal optical sensor 130, and embodiments in which a transversal position in a first transversal direction is determined by a first transversal optical sensor and wherein at least one further transversal position in at least one further transversal direction is determined by at least one further transversal optical sensor.
[0446] The at least one transversal optical sensor 130 is adapted to generate at least one transversal sensor signal. This transversal sensor signal may be transmitted by one or more transversal signal leads 140 to at least one evaluation device 142 of the detector 110, which will be explained in further detail below.
[0447] The longitudinal optical sensors 132 each comprise at least one sensor region 136, too. Preferably, one, more or all of the longitudinal optical sensors 132 are transparent, but the last longitudinal optical sensor 144 of the longitudinal optical sensor stack 134, i.e. the longitudinal optical sensor 132 on the side of the stack 134 facing away from the object 112, may fully or partially be intransparent.
[0448] Each of the longitudinal optical sensors 132 is designed to generate at least one longitudinal sensor signal in a manner dependent on an illumination of the respective sensor region 136 by the light beam 138. The longitudinal sensor signals, given the same total power of the illumination, is dependent on a beam cross-section of the light beam 138 in the respective sensor region 136, as will be outlined in further detail below. Via one or more longitudinal signal leads 146, the longitudinal sensor signals may be transmitted to the evaluation device 142. As will be outlined in further detail below, the evaluation device may be designed to generate at least one item of information on at least one transversal position of the object 112 by evaluating the at least one transversal sensor signal and to generate at least one item of information on at least one longitudinal position of the object 112 by evaluating the longitudinal sensor signal. For this purpose, the evaluation device 142 may comprise one or more electronic devices and/or one or more software components, in order to evaluate the sensor signals, which is symbolically denoted by transversal evaluation unit 148 (denoted by xy) and longitudinal evaluation unit 150 (denoted by z). By combining results derived by these evolution units 148, 150, a position information 152, preferably a three-dimensional position information, may be generated (denoted by x, y, z).
[0449] The evaluation device 142 may be part of a data processing device 154 and/or may comprise one or more data processing devices 154. The evaluation device 142 may be fully or partially integrated into the housing 118 and/or may fully or partially be embodied as a separate device which is electrically connected in a wireless or wire-bound fashion to the optical sensors 114. The evaluation device 142 may further comprise one or more additional components, such as one or more electronic hardware components and/or one or more software components, such as one or more measurement units (not depicted in
[0450] In this exemplary embodiment, the evaluation device 142 may further be adapted to generate the at least one item of information on the color of the object 112 by evaluating the modulation frequency related to the light beam 138 which impinges the optical sensor 114. According to the present embodiment, which comprises the arrangement where the corresponding modulation device 137 modulates the light in each separate light path with a specific modulation frequency, the evaluation device is preferably adapted to generate the at least one item of information on the color of the object 112 by performing a frequency analysis, in particular a Fourier transformation or a related procedure, of the optical signal, thus acquiring a contribution of the respective light beam 139 to the optical signal by taking into account its respective modulation frequency.
[0451]
[0452] In this particular embodiment, the light beam first travels through at least one transfer device 120, such as one or more optical systems, preferably one or more lenses 122, and the at least one modulation device 137 until it impinges the beam-splitting device 129 which comprises a prism 141 which splits the incoming light beam 138, in this exemplary embodiment, into three separate light beams 139, wherein each of the three separate light beams 139 comprises a specific color due to the well-known effect of the prism 141. Subsequently, each of the three separate light beams 139 impinges one of the three separate stacks each comprising at least one optical sensor 114. In particular, each separate stack may comprise at least one longitudinal optical sensor 130 and/or at least one transversal optical sensor 132 which may especially be adapted to requirements for detecting the specific color as comprised in the respective separate light beam 139 by which it is impinged. However, other arrangements may be feasible, such as providing three identical separate stacks.
[0453] In this exemplary embodiment, the evaluation device 142 may further be adapted to generate the at least one item of information on the color of the object 112 by comparing signals of at least two optical sensors, in particular, by using calibration data from a look-up table.
[0454] With respect to the other features as presented in an exemplary fashion in
[0455] A further exemplary embodiment of the detector 110 according to the present invention is shown in
[0456] In this particular embodiment, the light beam first travels through at least one modulation device 137 until it impinges the beam-splitting device 129 which here comprises a trichroic prism 143 which also here splits the incoming light beam 138 into three separate light beams 139, wherein each of the three separate light beams 139 comprises a specific color due to the known effect of the trichroic prism 143. As an example, the beam-splitting device 129 may split the incoming light-beam 138 into three separate light beams 139 which may exhibit a color being different from the color of all other separate light beams 139, such as between 600 nm and 780 nm (red), between 490 nm and 600 nm (green), and between 380 nm and 490 nm (blue). Subsequently, each of the three separate light beams 139 again impinges one of the three separate stacks each comprising at least one optical sensor 114. Also here, each separate stack may particularly comprise at least one longitudinal optical sensor 130 and/or at least one transversal optical sensor 132 which may particularly be sensitive within a spectral region related to the respective color, such as within the red spectral region, the green spectral region, or the blue spectral region, respectively, in the above described example. However, other arrangements may be feasible, such as providing three identical separate stacks.
[0457] In this exemplary embodiment, the evaluation device 142 may further be adapted to generate the at least one item of information on the color of the object 112 by evaluating the corresponding optical sensor signal of the separate stack being arranged on the separate light path which may be designed to generate a sensor signal depending on the illumination of the sensor region of the separate optical sensor by the separate light beam. In the above described example, wherein the optical sensor signal of the each of the three separate stack being particularly sensitive to red, green, and blue are recorded separately, the respective optical sensor signals are combined within the evaluation device 142 in order to provide a single color within a coordinate system in color space, such as determining CIE coordinates.
[0458] With respect to the other features as presented in an exemplary fashion in
[0459] A further exemplary embodiment of the detector 110 according to the present invention is shown in
[0460] In this particular embodiment, the light beam first travels through at least one further transfer device 120, such as one or more optical systems, preferably one or more lenses 122, and the at least one modulation device 137 until it impinges the beam-splitting device 129 which comprises a wavelength-sensitive switch 145. The wavelength-sensitive switch 145 as employed here comprises a single common optical port 147 and a number of opposing multi-wavelength ports 149 where each wavelength input from the single common port 147 may be switched or routed to any one of the number of multi-wavelength ports 149. Accordingly, the wavelength-sensitive switch 145 may only allow passing a single light beam 138 comprising a specific color during a time interval, whereas all other colors besides the specific color may be blocked during the time interval. As mentioned above, the color may be selected spontaneously, such as from a 2D camera image, or to a predefined procedure, such as alternatingly switching between a number of preselected colors.
[0461] In this exemplary embodiment, the evaluation device 142 may further be adapted to generate the at least one item of information on the color of the object 112 by comparing signals of at least two optical sensors, in particular, by using calibration data from a look-up table.
[0462] With respect to the other features as presented in an exemplary fashion in
[0463] In
[0464] The transversal optical sensor 130 comprises a transparent substrate 158, such as a substrate made of glass and/or a transparent plastic material. The setup further comprises a first electrode 160, an optical blocking layer 162, at least one n-semiconducting metal oxide 164, sensitized with at least one dye 166, at least one p-semiconducting organic material 168 and at least one second electrode 170. These elements are depicted in
[0465] As an exemplary embodiment, the substrate 158 may be made of glass, the first electrode 160 may fully or partially be made of fluorine-doped tin oxide (FTO), the blocking layer 162 may be made of dense titanium dioxide (TiO2), the n-semiconducting metal oxide 164 may be made of nonporous titanium dioxide, the p-semiconducting organic material 168 may be made of spiro-MeOTAD, and the second electrode 170 may comprise PEDOT:PSS. Further, dye ID504, as e.g. disclosed in WO 2012/110924 A1, may be used. Other embodiments are feasible.
[0466] As depicted in
[0467] Contrarily, the second electrode 170 comprises at least two partial electrodes 176. As can be seen in the top-view in
[0468] The partial electrodes 176, in this specific embodiment, form a frame which surrounds the sensor region 136. As an example, a rectangular or, more preferably, a square frame may be formed. By using appropriate current measurement devices, electrode currents through the partial electrodes 176 may be determined individually, such as by current measurement devices implemented into the evaluation device 142. By comparing e.g. electrode currents through the two single x-partial electrodes 178, and by comparing the electrode currents through the individual y-partial electrodes 180, x- and y-coordinates of a light spot 184 generated by the light beam 138 in the sensor region 136 may be determined, as for the outlined with respect to
[0469] In
[0470] In
[0471] It shall be noted that, in
[0472] According to well-known imaging equations, the object 112 is imaged onto the sensor region 136 of the transversal optical sensor 130, thereby generating an image 186 of the object 112 on the sensor region 136, which, in the following, will be considered a light spot 184 and/or a plurality of light spots 184.
[0473] As can be seen in the partial images 3B and 3D, the light spot 184 on the sensor region 136 will lead, by generating charges in the layer setup of the sDSC, electrode currents, which, in each case, are denoted by i.sub.1 to i.sub.4. Therein, electrode currents i.sub.1, i.sub.2 denote electrode currents through partial electrodes 180 in y-direction and electrode currents i.sub.3, i.sub.4 denote electrode currents through partial electrodes 178 in x-direction. These electrode currents may be measured by one or more appropriate electrode measurement devices simultaneously or sequentially. By evaluating these electrode currents, x- and y-coordinates may be determined. Thus, the following equations may be used:
[0474] Therein, f might be an arbitrary known function, such as a simple multiplication of the quotient of the currents with a known stretch factor and/or an addition of an offset. Thus, generally, the electrode currents i.sub.1 to i.sub.4 might form transversal sensor signals generated by the transversal optical sensor 130, whereas the evaluation device 142 might be adapted to generate information on a transversal position, such as at least one x-coordinate and/or at least one y-coordinate, by transforming the transversal sensor signals by using a predetermined or determinable transformation algorithm and/or a known relationship.
[0475] In
[0476] As can be seen in the schematic cross-sectional view in
[0477] It shall be noted that, in
[0478] However, as depicted in
[0479] In
[0480] The second electrode 170, however, in the setup of
[0481] In the exemplary embodiment shown in
[0482] The use of the transparent electrically conductive polymer 188 allows for an embodiment of the longitudinal optical sensor 132 in which both the first electrode 160 and the second electrode 170 are at least partially transparent. The same, preferably, holds true for the transversal optical sensor 130. In
[0483] In
[0484] Again, the measurement starts with an emission and/or reflection of one or more light beams 138 by at least one object 112. The object 112 may comprise an illumination source 192, which may be considered as a part of the detector 110. Additionally or alternatively, a separate illumination source 192 may be used.
[0485] Due to a characteristic of the light beam 138 itself and/or due to beam shaping characteristics of the transfer device 120, preferably of the at least one lens 122, the beam properties of the light beam 138 in the region of the longitudinal optical sensors 132 at least partially are known. Thus, as depicted in
[0486] In
[0487] In
[0488] As can be seen in
I=f(n,a).
[0489] Therein, I denotes the photo current provided by each longitudinal optical sensor 132, such as a photo current measured in arbitrary units, as a voltage over at least one measurement resistor and/or in amps. n denotes the overall number of photons impinging on the sensor region 136 and/or the overall power of the light beam in the sensor region 136. A denotes the beam cross-section of the light beam 138, provided in arbitrary units, as a beam waist, as a beam diameter of beam radius or as an area of the light spot 134. As an example, the beam cross-section may be calculated by the 1/e.sup.2 diameter of the light spot 184, i.e. a cross-sectional distance from a first point on a first side of a maximum intensity having an intensity of 1/e.sup.2 as compared to the maximum intensity of the light spot 184, to a point on the other side of the maximum having the same intensity. Other options of quantifying the beam cross-section are feasible.
[0490] The setup in
[0491] Thus, by evaluating the photo currents and/or other types of longitudinal sensor signals of the longitudinal optical sensors 132 of the detector 110, the light beam 138 may be characterized. Since the optical characteristics of the light beam 138 depend on the distance of the object 112 from the detector 110, by evaluating these longitudinal sensor signals, a position of the object 112 along the optical axis 116, i.e. a z-position, may be determined. For this purpose, the photo currents of the longitudinal optical sensors 132 may be transformed, such as by using one or more known relationships between the photo current I and the position of the object 112, into at least one item of information on a longitudinal position of the object 112, i.e. a z-position. Thus, as an example, the position of the focal point 194 may be determined by evaluating the sensor signals, and a correlation between the focal point 194 and a position of the object 112 in the z-direction may be used for generating the above-mentioned information. Additionally or alternatively, a widening and/or narrowing of the light beam 138 may be evaluated by comparing the sensor signals of the longitudinal sensors 132. As an example, known beam properties may be assumed, such as a beam propagation of the light beam 138 according to Gaussian laws, using one or more Gaussian beam parameters.
[0492] Further, the use of a plurality of longitudinal optical sensors 132 provides additional advantages as opposed to the use of a single longitudinal optical sensor 132. Thus, as outlined above, the overall power of the light beam 138 generally might be unknown. By normalizing the longitudinal sensor signals, such as to a maximum value, the longitudinal sensor signals might be rendered independent from the overall power of the light beam 138, and a relationship
I.sub.n=g(A)
may be used by using normalized photo currents and/or normalized longitudinal sensor signals, which is independent from the overall power of the light beam 138.
[0493] Additionally, by using the plurality of longitudinal optical sensors 132, an ambiguity of the longitudinal sensor signals may be resolved. Thus, as can be seen by comparing the first and the last image in
[0494] In
[0495] In this experiment, longitudinal sensor signals are provided for a variety of modulation frequencies of the light beam, for 0 Hz (no modulation), 7 Hz, 377 Hz and 777 Hz. As can be seen in the figure, for modulation frequency 0 Hz, no FiP effect or only a very small FiP effect, which may not easily be distinguished from the noise of the longitudinal sensor signal, may be detected. For higher modulation frequencies, a pronounced dependency of the longitudinal sensor signal on the cross section of the light beam may be observed. Typically, modulation frequencies in the range of 0.1 Hz to 10 kHz may be used for the detector according to the present invention, such as modulation frequencies of 0.3 Hz.
Human-Machine Interface, Entertainment Device and Tracking System:
[0496] In
[0497] By way of example, at least one detector 110, according to the present invention can once again be provided, for example, in accordance with one or more of the embodiments described above, with one or a plurality of optical sensors 114, which may comprise one or more transversal optical sensors 130 and one or more longitudinal optical sensors 132. Further elements of the detector 110 can be provided, which are not illustrated in
[0498] The human-machine interface 196 can be designed to enable an exchange of at least one item of information between a user 200 and a machine 202, which is merely indicated in
[0499] The human-machine interface 196 can be designed for example to generate, by means of the detector 110, at least one item of geometrical information of the user 200 by means of the detector 110 and can assign the geometrical information at least to one item of information, in particular at least one control command. For this purpose, by way of examples, by means of the detector 110, a movement and/or a change in posture of the user 200 can be identified. For example, as indicated in
[0500] The machine 202 can furthermore comprise one or a plurality of further human-machine interfaces, which need not necessarily be embodied according to the invention, for example, as indicated in
[0501] The at least one evaluation device 142 and/or parts thereof may further function as a track controller 201 of the tracking system 199. Additionally or alternatively, one or more additional track controllers 201 may be provided, such as one or more additional data evaluation devices. The track controller 201 may be or may comprise one or more data memories, such as one or more volatile and/or non-volatile memories. In this at least one data memory, a plurality of subsequent positions and/or orientation of one or more objects of parts of an object may be stored, in order to allow for storing a past trajectory. Additionally or alternatively, a future trajectory of the object and/or parts thereof may be predicted, such as by calculation, extrapolation or any other suitable algorithm. As an example, a past trajectory of an object or a part thereof may be extrapolated to future values, in order to predict at least one of a future position, a future orientation and a future trajectory of the object or a part thereof.
[0502] In the context of an entertainment device 198, said machine 202 can be designed for example to carry out at least one entertainment function, for example at least one game, in particular with at least one graphical display on the display 208 and, optionally, a corresponding audio output. The user 200 can input at least one item of information, for example via the human-machine interface 196 and/or one or more other interfaces, wherein the entertainment device 198 is designed to alter the entertainment function in accordance with the information. By way of example, specific movements or one or more virtual articles, for example of virtual persons in a game and/or movements of virtual vehicles in a game, may be controlled by means of corresponding movements of the user 200 and/or one or more body parts of the user 200, which, in turn, may be recognized by the detector 110. Other types of control of at least one entertainment function by the user 200, by means of the at least one detector 110, are also possible.
Exemplary Embodiments of sDSCs for a 3-D Position Sensor:
[0503] The practical implementation of the FiP-effect of the sDSCs in the form of a 3-D sensor, and achieving good spatial resolution both in the x,y- and in the z-direction, typically may require the cells to have an active area of approximately 1 cm1 cm and meet certain requirements. Therefore, in the following, preferred requirements for the individual cells of the at least one transversal optical sensor and/or the at least one longitudinal optical sensor are given. It shall be noted, however, that other embodiments are feasible.
Optical Properties of the at Least One Transversal Optical Sensor and/or the at Least One Longitudinal Optical Sensor:
[0504] As can be seen in
[0505] To ensure that sufficient illumination reaches the last cell and it supplies a useful current signal, the front five cells may have only low absorption at the excitation wavelength. The wavelength used for excitation should be around 700 nm.
Cross-Resistance of the Transversal Optical Sensors:
[0506] To achieve precise x,y resolution, there has to be a sufficient potential difference between each pair of opposite sides in this square cell.
[0507] Even without a silver back electrode, sufficiently good electron transport from the p-type conductor into the oxidized dye has to be ensured across the entire surface area of the cells so that the dye is regenerated rapidly by a supply of electrons. Since the p-type conductor itself has very low conductance (10.sup.5 S/cm), a conducting layer needs to be coated onto the p-type conductor. Thanks to this additional layer, a defined cross-resistance R is to be achieved between the opposite sides of this square cell.
Transparency of the Transversal Optical Sensors:
[0508] Due to their good conductance, normal solar cells have back electrodes (second electrodes) made of silver. The cells being developed here, however, have to be transparent, which is why the 1 cm.sup.2 cell area typically requires a transparent back electrode. The material preferably used for this purpose is the conducting polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) in aqueous dispersion. The conjugated polymer PEDOT:PSS is highly transparent; it absorbs in the blue-green region (450-550 nm) only at considerable layer thicknesses, and only minimally in the red spectral range.
[0509] The additional PEDOT layer makes possible good electron transport in the p-type conductor. To improve the conductance of this layer and provide contacts, four silver electrodes 1 cm in length are vapor-deposited around the square cell. The arrangement of the silver electrodes is shown in
Extinction of the Cells of the at Least One Optical Sensor:
[0510] It is not only the back electrode that has to be transparent, but the entire cell. To ensure that a sufficient amount of light still reaches the last cell in the stack, the extinction of the front five cells should be as low as possible. This is determined first and foremost by the dye's absorption. The extinction of a solar cell, i.e. the absorption of light by the dye, has a decisive effect on the cell's output current. Typically, the wavelength-dependent absorption spectrum has a maximumthe wavelength of maximum absorption is characteristic of the particular dye used. The more dye has been adsorbed in the np TiO2 layer, the higher the cell's absorption. The more dye molecules are adsorbed, the more electrons can reach the cb of the TiO2 through optical excitation and the higher the current. A cell with higher extinction will, therefore, have a higher output current than one with low extinction.
[0511] The objective here is to obtain the maximum total current from the complete cell arrangementwhich in the ideal case is divided equally among all the cells. Since the intensity of the light is attenuated by absorption in the cells, the ones located further back in the stack receive less and less light. In order, nonetheless, to obtain similar output currents from all six cells, it would make sense for the front cells to have lower extinction than the ones at the back. As a result, they will stop less of the light reaching the following cells, which in turn will absorb a larger proportion of the already weakened light. Through optimal adjustment of the extinctions at the positions of the cells in the stack, in this way theoretically one could obtain the same current from all the cells.
[0512] The extinction of a solar cell can be adjusted by staining with a dye and by controlling the thickness of the np TiO2 layer.
Optimizing the Extinction and the Output Current of the Cells of the Longitudinal Optical Sensor Stack:
[0513] The last cell in the stack preferably should absorb almost all the incident light. For this reason, this cell should have maximum extinction. Starting with the current obtained under maximum extinction at the last cell, the extinctions of the front cells need to be so adjusted that all cells together supply a maximum total current, one that is distributed as uniformly as possible across all the cells.
[0514] Optimizing the stack's output currents is carried out as follows: [0515] The choice of dye [0516] Maximum extinction/maximum output current of the last cell [0517] Dye concentration for staining the last cell [0518] Staining time of the last cell [0519] Optimum thickness of the last cell's np TiO.sub.2 layer [0520] Maximum output current of the complete stack [0521] Optimum thickness of the np TiO.sub.2 layers of the front five cells
[0522] The extinction was measured with a Zeiss spectrometer MCS 501 UV-NIR using Zeiss lamp MCS 500. The results were evaluated with an Aspect Plus software program.
Choice of Dye:
[0523] To begin with, a dye should to be found that absorbs sufficiently at the excitation wavelength of approximately 700 nm. The ideal dye for solar cells typically has a broad absorption spectrum and should absorb completely the incident light below a wavelength of ca. 920 nm. In actual fact, most dyes have an absorption maximum in the wavelength range between 450-600 nm; above 650 nm they usually absorb weakly or not at all.
[0524] The dye with which the first experiments were performed was ID504, as e.g. disclosed in WO 2012/110924 A1. This dye, however, turned out to exhibit only a low absorption in the range of 700 nm. Therefore, for the stack, the dye D-5 (also referred to as ID 1338) was used. Preparation, structure and properties of the Dye D-5 are disclosed in WO 2013/144177 A1.
[0525] Additionally or alternatively, however, other dyes may be used. The staining time, i.e. the duration of staining of the TiO.sub.2-layer with the respective dye, turned out to have an influence on the absorption properties. The tests were performed with cells having np TiO.sub.2 layers having a thickness of 1.3 microns. The absorption maximum of D-5 is around 550-560 nm which exhibits an extinction 59000 at this maximum.
[0526] In this experimental series, the dye concentration was 0.3 mM and the staining time was increased so as to be 10 to 30 minutes. A pronounced increase in extinction at longer staining times was observed, so finally staining times of 30 min. were used for D-5.
[0527] Still, even after optimizing the staining time, the absorption was determined to be rather very low. Therefore, generally, the absorption will have to be maximized by increasing the dye concentration, the staining time and the thickness of the np TiO.sub.2 layer.
Dye Concentration and Staining Time of the Last Cell in the Longitudinal Optical Sensor Stack:
[0528] Several experiments regarding the staining time and the dye concentration were performed. The standard concentration of the dye solution for a layer thickness of the TiO.sub.2-layers of 1-2 microns was 0.5 mM. At these concentrations, the dye should already be present in excess. Here the dye concentration was increased to 0.7 mM. In order to prevent inhomogeneities across the cell's area, the dye solution was cleaned by removing undissolved dye particles and other impurities, using a 0.2 micron syringe filter, before placing the cells in it.
[0529] If the dye is present in excess, then after a 1 hour staining time a dye monolayer dye should have been adsorbed to the surface of the np TiO.sub.2 layer, which leads to maximum absorption by the dye being used. The maximum staining time tested here was 75 minutes, which was finally used for the cells.
[0530] Finally, cells having a layer thickness of the TiO.sub.2-layer of 1.3 microns, a dye concentration of 0.7 mM and a staining time of 75 min was used. The cell's extinction turned out to be 0.4 at 700 nm.
The Np TiO.SUB.2 .Layer Thickness of the Last Cell of the Longitudinal Optical Sensor Stack:
[0531] Ultimately, the thickness of the nanoporous (np) layer and thus the TiO.sub.2 surface area available for dye adsorption may be an important factor influencing the absorption behavior and therefore the cells' output current. So far, maximizing the extinction was done in cells with np TiO.sub.2 layers whose thickness was 1.3 microns. Since more dye can be adsorbed in thicker np TiO.sub.2 layers, the thickness of the TiO.sub.2 layer was increased in steps to 3 microns, and the thickness at which the greatest output current occurred was determined.
[0532] The nanoporous TiO.sub.2 layers were applied by spin coating. Spin coating is suitable for applying low-volatility substances dissolved in a high-volatility solvent (here: terpineol). As a starting product, TiO.sub.2 paste made by Dyesol (DSL 18 NR-T) was used. This paste was mixed with terpineol, which decreases the viscosity of the paste. Depending on the composition ratio of the paste:terpineol mixture, and at a constant spin velocity of 4500 1/min, np TiO.sub.2 layers of varying thicknesses are obtained. The higher the terpineol proportion, the lower the viscosity of the diluted paste and the thinner the cells will be.
[0533] The diluted TiO.sub.2 paste was also cleaned using a 1.2 micron syringe filter to remove larger particles, before applying the paste the next day by spin coating on the cells coated with blocking layer.
[0534] When varying the np TiO.sub.2 layer thickness, it should be noted that the concentration of the p-type conductor dissolved in chlorobenzene needs to be adjusted. Thicker np layers have a larger cavity volume that has to be filled with p-type conductor. For this reason, in the case of thicker np layers the amount of supernatant p-type conductor solution on top of the np layer is smaller. To ensure that the solid p-type conductor layer remaining on the np TiO.sub.2 layer after spin coating has a constant thickness (the solvent evaporates during spin coating), higher p-type conductor concentrations are needed for thick np TiO.sub.2 layers than for thin ones. The optimal p-type conductor concentrations are not known for all the TiO.sub.2 layer thicknesses tested here. For this reason, the p-type conductor concentration is varied for the unknown layer thicknesses and the output currents compared for equal layer thicknesses but different p-type conductor concentrations.
[0535] The chosen starting value for the layer thickness variation was a 1.3 microns for the np TiO.sub.2 layer. 1.3 microns corresponds to a TiO.sub.2 paste:terpineol mass composition of 5 g:5 g. A test series with cells whose np TiO.sub.2 layers are thicker than 1.3 microns will show at which layer thickness the largest output current is obtained from the last cell in the stack.
[0536] These cells were stained with the aforementioned optimized parameters for maximum extinction (D-5; c=0.7 mM; staining time: 75 minutes). The extinction of these cells was found to be approximately 0.6 at 700 nm.
[0537] Since the last cell generally does not have to be transparent, the back electrode was vapor-deposited on the whole 1 cm.sup.2 area directly onto the p-type conductor without PEDOT.
[0538] The measurement results indicated that, as expected, the output currents of the cells with a whole-area back electrode (second electrode) are much higher. Highest output currents were obtained with a TiO.sub.2:terpineol mass ratio of 5:3. This corresponds to a TiO.sub.2 layer thickness of 2-3 microns.
[0539] Therefore, in subsequent experiments, a TiO.sub.2 paste:terpineol composition of 5:3 was used for the last cell in the stack. The back electrode was vapor-deposited across the entire 1 cm.sup.2 cell area.
The Np TiO.SUB.2 .Layer Thickness of the Front Cells of the Longitudinal Optical Sensor Stack:
[0540] Starting from the maximum output current obtained with the last cell, the thicknesses of the front cells' np TiO.sub.2 layers are to be so adjusted that every cell in the stack generates the maximum possible output current. This requires low extinction values in the front cells.
[0541] During the experiments, it turned out that, in practical terms, it is rather difficult to obtain reproducible low extinctions through the dye concentration and staining time parameters. In order to make cells with low, reproducible extinction, therefore, it makes sense to fabricate cells with thin np TiO.sub.2 layers and to keep them in the dye solution for the time needed to ensure dye saturation of the np TiO.sub.2 surface. The terpineol proportion in the TiO.sub.2 layers was increased in a stepwise fashion. All the cells were stained under the same conditions. Since their extinction is intended to be decreased significantly, the dye concentration here was 0.5 mM, and the staining time was 60 minutes.
[0542] Surprisingly, in this series, the cell's output voltages turned out to begin with an increase in output current with decreasing np TiO.sub.2 layer thickness. The optimum out of the tested TiO.sub.2 paste dilutions turned out to be 5:6. At higher dilutions and therefore thinner np TiO.sub.2 layers, the output current tends to decrease. The reason for the exception to this trend at a dilution of 5:9 is likely to be optimal adjustment of the p-type conductor concentration of 100 mg/ml for this layer thickness.
[0543] If, however, one considers the decrease in extinction relative to that of the output current, it makes sense to accept the lower output current in order to ensure that the following cells receive very much more light than would be the case with 5:6 dilution. Photographs of cells with TiO.sub.2:terpineol mixtures of 5:4.1, 5:6 and 5:10 were taken, which illustrated this effect. Effects of inhomogeneity were observed. In order to achieve a homogeneous layer within a 1 cm.sup.2 cell, the TiO.sub.2 area was increased for later cells such that the region in which the TiO.sub.2 banks up during spin coating lies outside the silver electrodes and thus outside the cell.
[0544] The construction of the cell stack with regard to the TiO.sub.2 layer's thickness in the cells and their positioning in the stack, was carried out by testing various arrangements of cells with np TiO.sub.2 layers of various thicknesses.
Preparation and the Properties of a Dye Sensitized Solar Cell (DSC) Prepared with the Dye D-5
[0545] FTO (tin oxide doped with fluorine) glass substrates (<12 ohms/sq, A11DU80, supplied by AGC Fabritech Co., Ltd.) were used as the base material, which were successively treated with glass cleaner, Semico Clean (Furuuchi Chemical Corporation), fully deionized water and acetone, in each case for 5 min in an ultrasonic bath, then baked for 10 minutes in isopropanol and dried in a nitrogen flow.
[0546] A spray pyrolysis method was used to produce the solid TiO.sub.2 buffer layer. Titanium oxide paste (PST-18NR, supplied by Catalysts & Chemicals Ind. Co., Ltd.) was applied onto the FTO glass substrate by screen printing method. After being dried for 5 minutes at 120 C., a working electrode layer having a thickness of 1.6 m was obtained by applying heat treatment in air at 450 C. for 30 minutes and 500 C. for 30 minutes. Obtained working electrode is then treated with TiCl.sub.4, as described by M. Grtzel et al., for example, in Grtzel M. et al., Adv. Mater. 2006, 18, 1202. After sintering the sample was cooled to 60 to 80 C. The sample was then treated with an additive as disclosed in WO 2012/001628 A1. 5 mM of the additive in ethanol was prepared and the intermediate was immersed for 17 hours, washed in a bath of pure ethanol, briefly dried in a nitrogen stream and subsequently immersed in a 0.5 mM solution of dye D-5 in a mixture solvent of acetonitrile t-butyl alcohol (1:1) for 2 hours so as to adsorb the dye. After removal from the solution, the specimen was subsequently washed in acetonitrile and dried in a nitrogen flow.
[0547] A p-type semiconductor solution was spin-coated on next. To this end a 0.165M 2,2,7,7-tetrakis(N,N-di-p-methoxyphenyl-amine)-9,9-spirobifluorene (spiro-MeOTAD) and 20 mM LiN(SO.sub.2CF.sub.3).sub.2 (Wako Pure Chemical Industries, Ltd.) solution in chlorobenzene was employed. 20 ll/cm.sup.2 of this solution was applied onto the specimen and allowed to act for 60 s. The supernatant solution was then spun off for 30 s at 2000 revolutions per minute. The substrate was stored overnight under ambient conditions. Thus, the HTM was oxidized and for this reason the conductivity increased.
[0548] As the metal back electrode, Ag was evaporated by thermal metal evaporation in a vacuum at a rate of 0.5 nm/s in a pressure of 110.sup.5 mbar, so that an approximately 100 nm thick Ag layer was obtained.
[0549] In order to determine the photo-electric power conversion efficiency of the above photoelectric conversion device, the respective current/voltage characteristic such as short-circuit current density J.sub.sc, open-circuit voltage V.sub.oc and fill factor FF was obtained with a Source Meter Model 2400 (Keithley Instruments Inc.) under the illumination of an artificial sunlight (AM 1.5, 100 mW/cm.sup.2 intensity) generated by a solar simulator (Peccell Technologies, Inc). As a result, the DSC prepared with the Dye D-5 exhibited the following parameters:
TABLE-US-00001 J.sub.sc [mA/cm.sup.2] V.sub.oc [mV] FF [%] [%] 10.5 721 59 4.5
Results of the Optimized Output Currents for the Longitudinal Optical Sensor Stack:
[0550] The best result in terms of the cell stack's output currents were obtained when all five transparent cells of the longitudinal optical sensors step have an np TiO.sub.2 layer thickness of 0.45 micrometers (i.e. a TiO.sub.2 paste dilution of 5:10). These cells with a 0.45 micrometers np TiO.sub.2 layer were stained for 60 minutes in a 0.5 mM dye solution. Only the last cell had a np TiO.sub.2 layer just under 3 micrometers and was stained for 75 minutes (0.7 mM). Since the last cell does not have to be transparent, the back electrode (second electrode) of the last cell was a vapor-deposited silver layer across the whole 1 cm.sup.2 area so as to be able to pick up the maximum possible current. The following photo currents were observed with this stack, in order from the first cell to the last cell of the stack: [0551] Current [A]: 37 9.7 7.6 4.0 1.6 1.9
[0552] The first five cells were made identically. The last cell had a thicker np TiO.sub.2 layer and a silver back electrode vapor-deposited across the whole cell area. One can see that the current of the second cell has already dropped to of the first cell's. Even in these five highly transparent cells, the last cell's current is only a fraction of the current in the first cell. The cells were excited with a red laser (690 nm, 1 mW) directed at the centre of the cell area.
[0553] The current obtained with cells with a TiO.sub.2 terpineol dilution of 5:9, 5:8 or 5:7 (i.e. thicker cells) was at most 10 A larger than the current of a cell with 5:10 dilution of the TiO.sub.2 paste. These cells, however, exhibited a significantly higher extinction, as a result of which the output current of the following cells decreases considerably.
[0554] The cells with a TiO.sub.2 dilution of 5:6, in whichcompared with the TiO.sub.2 dilutions of 5:9; 5:8 and 5:7a significantly higher current was obtained, nevertheless absorbed so much light that no more light reaches the last cell of the stack. Even when placing just one of these cells in position 5 with four preceding 450 nm thin cells, the output current of the last cell decreased considerably, such that the last cell supplies practically no more current.
[0555] It needs mentioning that each of these cells in the test stack was sealed with an additional glass plate for protection against ambient effects. This, however, created many additional interfaces at which the light beam of the 690 nm laser (1 mW) can be reflected and scattered, as a result of which the extinction of such a sealed cell is higher. In the later device the cell stack was kept in nitrogen, which is why the sealing becomes unnecessary and the cells lie directly on top of each other. This decreased the stack's extinction, since the losses resulting from scattering at the cover glasses no longer occur.
Cross-Resistance of the Transversal Optical Sensors:
[0556] A defined cross-resistance between the opposite sides of the square cell makes precise x,y resolution possible. The principle of x,y resolution is illustrated in
Factors Affecting the Cross-Resistance:
[0557] The PEDOT was also applied to the cells by spin coating. During the spinning process, the solvents ethanol and isopropanol evaporate whereas the low-volatility PEDOT remains on the substrate in the form of a film. The resistance of this layer depends on the conductance of the PEDOT being used and on the thickness of the layer:
where is the resistivity, I the distance across which the resistance is measured and A the cross-sectional area through which the charge carriers flow (A is a function of the PEDOT layer's thickness).
[0558] According to known principles of spin-coating, the layer thickness d to be expected when coating a non-Newtonian fluid can be determined by:
where x.sub.s is the PEDOT percentage in the mixed diluted solution, u.sub.k is the kinematic viscosity, e the evaporation rate of the solvent(s) and the angular velocity during spin coating. The evaporation rate is proportional to .sup.1/2.
[0559] The thickness of the PEDOT layer can, therefore, be affected by various parameters: the angular velocity, the viscosity of the PEDOT solution and the percentage of PEDOT in the solution. The angular velocity can be varied directly. The viscosity and the percentage of PEDOT in the solution can only be affected indirectly, i.e. via the ratio at which the PEDOT is mixed with ethanol and isopropanol.
[0560] The following parameters, therefore, can be used in order to adjust the cross-resistance, and they will be optimized in due course: [0561] The choice of PEDOT [0562] The layer thickness of the PEDOT [0563] The PEDOT/solvent ratio [0564] The spin speed during the PEDOT's spin coating [0565] The number of PEDOT layers [0566] The time interval t between applying and spin coating the PEDOT
Optimizing the Cross-Resistance:
[0567] The PEDOT solution was mixed with ethanol and isopropanol in a standard volumetric ratio of 1:1:1, and larger particles removed with a 0.45 micrometer syringe filter. The entire cell was covered with this diluted PEDOT solution (approximately 900 microliters were needed per substrate) and spin coated at a speed of 2000 1/s. At this speed, 30 s turned out to suffice to remove and evaporate the solvents ethanol and isopropanol.
[0568] The aforementioned parameters were then varied systematically, with the objective of obtaining a cross-resistance of ca. 2 k between the opposite electrodes of the square cell.
Choice of PEDOT:
[0569] The greatest impact on the PEDOT layer's cross-resistance turned out to come from the conductance of the PEDOT solution used. In order to obtain a first impression of the order of magnitude of the resistances of such a PEDOT layer across 1 cm, three PEDOT products with very different conductances were tested: [0570] Clevios PVP Al 4083 from Heraeus [0571] Clevios PH 1000 from Heraeus [0572] Orgacon N-1005 from Sigma Aldrich
[0573] The relevant parameters of dynamic viscosity nd, ionisation potential IP and resistivity are summarised in Table 1. The IP is an important selection criterion for the PEDOT. The PEDOT's IP generally should be less than 5 eV in order to ensure good functionality of the cell.
TABLE-US-00002 TABLE 1 Relevant parameters for various PEDOTs. AI 4083 PH 1000 N-1005 .sub.d [mPas] 5-12 15-50 7-12 IP [eV] 5.2 4.8 N/A [cm] 500-5000 0.0012 75-120
[0574] For these first tests, 1.3 micrometer np TiO.sub.2 layers were coated onto FTO-free glass substrates. In this first experimental series, only 300 microliters of each of the three prepared PEDOT solutions were coated directly on np TiO.sub.2 layerswithout the staining or p-type conductor coating steps. For each PEDOT solution, three substrates with 1, 2 and 3 PEDOT layers were made. The resistance was measured by applying a layer of conducting silver paint at 1 cm spacing at several positions on each substrate.
[0575] It is to be expected that the resistance of the substrate fabricated in this way, will be smaller than the resistance resulting from applying the PEDOT on a smooth p-type conductor layer.
[0576] As expected, the experiments showed a decrease in cross-resistance with an increasing number of layers and therefore increasing total thickness of the PEDOT. The cross-resistance of Al 4083 is in the MO range even with three layers, therefore it was not used in further tests. PH 1000 with two applied layers was in the required range. The cross-resistance of N 1005 is also in the k range, and could be decreased through optimization. Since, however, it can be assumed that when applying the PEDOT on the smooth p-type conductor's surface the resistance will be higher than when applying it directly on the np TiO.sub.2 layer as in this test series, further optimizations will focus on PH 1000.
Applying Several PEDOT Layers:
[0577] A further option for increasing the total thickness of the PEDOT layer is to apply several PEDOT layers consecutively. Tests were conducted with 1 and 2 applied PEDOT layers. PH 1000 was mixed with ethanol and isopropanol at a 1:1:1 volumetric ratio. The cells were covered completely with 900 microliters of the PEDOT solution and the excess solution was removed by spin coating at an RPM of 2000 1/min.
[0578] Unlike the first experimental series, these tests were conducted on complete cells, i.e. stained cells coated with p-type conductor. The cross-resistance was measured between two circular vapour-deposited electrodes ca. 2 mm apart, in order to exclude errors resulting from different contact resistances of PEDOT/conducting silver paint and PEDOT/vapour-deposited silver. In addition, cell efficiency measurements can be automated with this electrode arrangement. These test cells are very much simpler and quicker to make than the square transparent ones, but they suffice for the requirements of these tests (for one thing, the cross-resistance of the PEDOT layer(s) is to be measured here across a defined section; for another, the cells are to be tested for functionality, i.e. whether there is good contact between the p-type conductor and the PEDOT and the IP of the PEDOT matches the energy level of the p-type conductor). The cross-resistance across 1 cm is calculated using equation 3.1assuming equal layer thickness and therefore equal area Athrough multiplication by the factor 5 (the resistivity of the solution is constant).
[0579] Table 2 shows the results of the resistance measurement between the two circular vapor-deposited back electrodes and the calculated cross-resistances across 1 cm for 1 and 2 PEDOT layers. The last column shows the efficiency of the cells. The smallest and largest measurements obtained in several tests are shown in each case.
TABLE-US-00003 TABLE 2 Results of resistance measurements for one and two PEDOT layers. Mixture Number of RPM R.sub.i=2 mm R.sub.i=1 cm ratio layers [1/min] [k] [k] [%] 1:1:1 1 2000 6-19 30-90 1.5-2.5 2 0.18-0.27 0.9-1.35 0.4-0.6
[0580] The difference in cross-resistances between one and two applied PEDOT layers can be seen clearly. For one PEDOT layer it is significantly higher than the required 2 k, for two layers it is very much lower. It is also evident, however, that the efficiency of the cells with two applied PEDOT layers is very much smaller, which means that the contact between the two PEDOT layers is poor. It should be noted that the efficiency being measured here refers to the circular cell, i.e. to a cell with a back electrode vapor-deposited across the whole surface. The efficiency of the square transparent cells, therefore, will be much lower still, which is why the idea of several PEDOT layers applied consecutively has to be discarded. Further experiments will attempt to minimize the cross-resistance of one PEDOT layer only.
[0581] It is noticeable that the resistance with two applied PEDOT layers is smaller than in the first experimental series, in which the PEDOT was applied directly onto the np TiO.sub.2 layer. Presumably, the reason for this discrepancy is that in the first experiments the layers were applied immediately after each other, even though the first PEDOT layer had not yet dried out completely. In this experiment, the cell was placed on the hotplate at 60 C. between applying the two layers.
[0582] As expected, in this experimental seriesin which the PEDOT was applied onto the p-type conductorthe cross-resistance with only one applied PEDOT layer was higher than when the PEDOT was applied onto the rough surface of the np TiO.sub.2.
Increasing the PEDOT Concentration of the Solution:
[0583] As mentioned above, usually, the PEDOT solution is mixed with ethanol and isopropanol at a volume ratio of 1:1:1 in order to decrease the viscosity of the solution and obtain homogeneous layers through spin coating. When the PEDOT proportion in the mixture is increased, the solution's viscosity rises. Due to the higher viscosity, an increase in the thickness of the PEDOT layer remaining on the cell after spin coating is expected (for comparison: .sub.d, ethanol, 20 C.=1.19 mPas; .sub.d, isopropanol, 20 C.=2.43 mPas; .sub.d,PEDOT=5-50 mPas).
[0584] In order to investigate the practical effect of the PEDOT solution's viscosity and the amount of substance it contains on layer thickness and therefore on the cross-resistance, the PEDOT proportion was increased a little to begin with, and then significantly. The volumetric mixture ratios ethanol:isopropanol:PEDOT tested here were as follows: [0585] 1:1:1 [0586] 1:1:2 [0587] 1:1:5 [0588] 1:1:10 [0589] 2:2:1
[0590] Since a preliminary experiment showed that small variations in PEDOT concentration do not result in significant differences as far as the resistance is concerned, the PEDOT proportion in the mixed solutions was increased considerably. This was the first experimental series in which the construction of the cells and the arrangement of the electrodes corresponded to those of the actual square cells.
[0591] The thickness of the cells' np TiO.sub.2 layer was 1.3 micrometers. Each time, a PEDOT layer with a different proportion of PH 1000 was applied. The PEDOT solution was spun for 90 seconds at 2000 or 1500 1/min. Then the PEDOT layer was dried for ca. 1 minute with the hot air blower, before the silver electrodes (ca. 2 micrometers thick) were vapor-deposited.
TABLE-US-00004 TABLE 3 Cross-resistances for various mixture ratios and spin speeds of PEDOT layers. Mixture Number RPM R ratio of layers [1/min] [k] 1:1:1 1 2000 22-39 1:1:5 31-51 1:1:10 29-36 1:1:1 1 1500 21-27 1:1:5 21-32 1:1:10 26-37
[0592] As can be seen in Table 3, the cross-resistance does not decrease as expected with the increasing PEDOT proportion in the applied solution. Both at an angular velocity of 2000 and of 1500 1/min, the cross-resistance increases with the increasing PEDOT concentration in the solution. However, it is also noticeable that the resistance tends to decrease with decreasing RPM for the same PEDOT proportion, but is still 10-15 orders of magnitude too high.
Adjusting the Time Interval Between Application and Spin Coating of the PEDOT (at) and Minimizing the RPM During Spin Coating:
[0593] The classic method for increasing layer thickness during spin coating is to decrease the angular velocity. In this way, layer thickness can easily be increased and the cross-resistance decreased. In the experimental series thus far, this was the only variation that led to a sensible result. The angular velocity during spin coating cannot, however, be decreased to an arbitrary value, since at excessively low RPM the solvent no longer evaporates sufficiently quickly which results in inhomogeneous PEDOT layers.
[0594] Tests have shown, however, that the time interval between applying the PEDOT solution to the substrate and starting the spin coating (and thus, removing excess solution from the substrate) has a significant effect on the cross-resistance. Therefore, subsequently, the cross-resistance was minimized through iterative optimization of the two parameters t and angular velocity during spin coating.
[0595] Therefore, over several tests series, the time interval t between applying the PEDOT solution to the cell and the start of spin coating was increased in steps from 30 seconds to 2 minutes, later in combination with RPM optimization from 1 to 3 minutes and finally from 3.5 to 5 minutes. This involves decreasing the RPM from 2000 1/min to 350 1/min. When decreasing the RPM to under 1000 1/min, 30 seconds turned out to no longer suffice for complete evaporation of the solvent. This time was, therefore, extended to 2 minutes in every case. Thereafter, the cells were dried with the hot air blower for approximately 1 minute before the electrodes were vapor-deposited.
RPM [1/min] 2000 1000 750 600 500 450 400 350
[0596] The results of the optimization are summarized in Tables 4 to 7.
[0597] In the first experimental series of the final optimization (Table 4), in which to begin with the time interval t between applying the PEDOT solution on the cell and spinning at constant angular velocity was increased, at an RPM of 1000 1/min there seems to be an optimum at t=60 s (4.1-4.2 k). For this time interval and a further decrease in RPM, a new minimum was obtained for 600 1/min (2.6-2.7 k).
TABLE-US-00005 TABLE 4 Optimization of the cross-resistance by optimizing the time interval t and the angular velocity during PEDOT solution spin coating - experimental series 1. Mixture Number of RPM t R ratio layers [1/min] [s] [k] 1:1:1 1 1000 30 8.5-8.7 60 4.1-4.2 90 4.7-4.8 120 5.4-5.8 750 60 9.0-9.2 600 60 2.6-2.7 500 60 3.7-4.0
TABLE-US-00006 TABLE 5 Optimization of the cross-resistance by optimizing the time interval t and the angular velocity during PEDOT solution spin coating - experimental series 2. Mixture Number of RPM t R ratio layers [1/min] [s] [k] 1:1:1 1 600 60 15.8-17.6 90 11.0-11.6 120 11.2-11.4 500 60 6.0-6.8 90 5.0 120 6.4-6.8 180 3.1-4.1
TABLE-US-00007 TABLE 6 Optimization of the cross-resistance by optimizing the time interval t and the angular velocity during PEDOT solution spin coating - experimental series 3. Mixture Number of RPM t R ratio layers [1/min] [s] [k] 1:1:1 1 500 180 0.4 450 180 0.6 400 180 1.1-1.3 350 180 2.0-2.7 350 210 1.8-2.5 350 240 1.6 350 270 1.5-1.8 350 300 1.8-1.9
TABLE-US-00008 TABLE 7 Optimization of the cross-resistance by optimizing the time interval t and the angular velocity during PEDOT solution spin coating - experimental series 4. Mixture Number of RPM t R ratio layers [1/min] [s] [k] 1:1:1 1 500 180 1.3-2.4 450 180 1.0-2.0
[0598] Since, however, the results do not differ substantially between 600 and 500 1/min, in the next experimental series the time interval t was increased further stepwise for both RPM values. The results are shown in Table 5.
[0599] A further decrease in RPM and increase in t did not exhibit further improvement. In fact, the cross-resistance even increased again at an RPM<450 1/min (see Table 6).
[0600] Since the values for 500 and 450 1/min lie very close together, a last comparative test was performed (see Table 7).
[0601] It was shown that the cross-resistance at an RPM of 450 1/min is slightly smaller than at 500 1/min. Since, however, no significant is achieved thereby and since PEDOT layers coated at an excessively low RPM are no longer homogeneous, 500 1/min was chosen as the optimal RPM. The time interval t is then 180 s.
[0602] Generally speaking, it is noticeable that the resistance values in the last set of experimental series, where there was a time interval between applying the PEDOT solution to the cell and starting the spinning, do not fluctuate as much within one series for constant parameters as before. In the last experimental series (Table 7), the two cross-resistances were measured on each of four cells (left-right and top-bottom) and the results varied only by ca. 1 k. The fact that in some cases the results from different series vary significantly for the same experimental parameters, is likely to be due to the production of the PEDOT solution since the individual experimental series in themselves provide coherent results.
[0603] The spin coater's open lid during the time interval t may be an important interference factor in these experiments. In one experimental series, it was not closed immediately after applying the PEDOT solution to the cell but only before spin coating. The cross-resistances measured in this experimental series are very much higher and there is a considerable variation in their values between the substratesbut not on any one substrate. It could not be determined exactly why the cross-resistance is so strongly influenced by the time interval t before the PEDOT solution's spin coating. Perhaps some of the PEDOT solution dries and adheres to the cell during this time, resulting in a thicker PEDOT layer.
Results of the Optimized Parameters:
[0604] The minimum cross-resistance obtained in this way lies between 1 and 3 k. The parameters that bring about a minimum cross-resistance here were: [0605] PEDOT: Clevios PH 1000 from Heraeus [0606] Number of layers: 1 [0607] PEDOT:ethanol:isopropanol ratio=1:1:1 [0608] Time interval between applying and spin coating the PEDOT: t=180 s [0609] RPM during PEDOT spin coating: n=500 1/min (t=120 s)
The Final Cells Used in the Experiments:
[0610] The cells used during the optimization process so far were made on thick 2.5 mm TEC 8 glass carriers, with the FTO layer already applied during the fabrication process. They have a highly homogeneous FTO layer, onto which the application of homogeneous np TiO.sub.2 layers is possible. This makes possible the fabrication of cells that appear homogeneous to the human eye.
[0611] For the technical realization of the sensor stack, however, the cells were made on thin 1 mm special glass carriers made of quartz glass, which were coated subsequently with FTO. Therein, loss carriers with beveled edges were used. The beveled edges served as bases for cells contacts. The silver contacts were vapor-deposited up to the edge of the bevels. This made it possible to contact the cells directly adjacent to each other in the stack individually with pins.
[0612] The subsequently applied FTO layer on these special carriers exhibited in part inhomogeneities arising from the fabrication process. The fabrication of homogeneous cells on these carriers turned out to be very difficult, as was shown by generating current diagrams of the final cells. Even in the first cell of the stack which supplied a homogeneous current signal across its entire area, four locations were identified that supplied lower currents due to inhomogeneities. Current diagrams were obtained by exciting the cells with a laser at a wavelength 690 of nm. The laser scanned the cells at 1 mm intervals. The cells were scanned in their final arrangement as a stack, i.e. the current diagram of the last cells was recorded with five thin cells located in front of the last cell.
[0613] At the excitation wavelength of 690 nm, the developed cells had an extinction of 0.13. At the maximum (at ca. 550 nm) the extinction of these cells was ca. 0.4. Despite this low absorption by the cells and the fact that the back electrode consists of a poorly conductingunlike silvertransparent layer, the efficiency of such a cell is still 0.3% (AM 1.5*), that of the last cell 2%.
[0614]
[0615] The last cell of the longitudinal optical sensor stack is intended to absorb the remaining light preferably completely, which is why it was chosen to have a significantly higher extinction than the front cells. In addition, it has a back electrode covering its entire area in order to supply maximum output current.
[0616] The cell shown in
[0617] When illuminating one of these single transparent final cells with a red laser (690 nm, 1 mW), this cell supplied a current of 30-40 A. The last longitudinal optical sensor provided a current of approximately 70 A. The cross-resistance between any two opposite electrodes in the first cell on these special glass carriers turned out to be 0.1 and 0.3 k.
[0618] Since the fabrication of transparent cells on the special glass carriers was problematic due to the poor FTO coating, these cells had to be fabricated in large numbers. The cells were screened, and only selected cells were used for the final setup of the detector forming a prototype 3-D sensor. For this screening procedure, specifically for the transversal optical sensor, the cells were excited by a laser beam (690 nm, 1 mW) at the center of the cell. If the cells are homogenous, the currents at all four contacts are equal (I1=I2=I3=I4). By comparing the currents, specific cells were selected for use in the prototype.
[0619] The x,y resolution achieved with the detector of the set-top turned out to be approximately 1 mm at a distance of 3 m. The z-resolution of this detective setup turned out to be approximately 1 cm.
LIST OF REFERENCE NUMBERS
[0620] 110 detector [0621] 112 object [0622] 114 optical sensors [0623] 116 optical axis [0624] 118 housing [0625] 120 transfer device [0626] 122 lens [0627] 124 opening [0628] 126 direction of view [0629] 128 coordinate system [0630] 129 beam-splitting device [0631] 130 transversal optical sensor [0632] 131 mirror [0633] 132 longitudinal optical sensor [0634] 133 semi-transparent mirror [0635] 134 longitudinal optical sensor stack [0636] 135 intransparent mirror [0637] 136 sensor region [0638] 137 modulating device [0639] 138 light beam [0640] 139 separate light beam [0641] 140 transversal signal lead [0642] 141 prism [0643] 142 evaluation device [0644] 143 trichroic prism [0645] 144 last longitudinal optical sensor [0646] 145 wavelength-sensitive switch [0647] 146 longitudinal signal leads [0648] 147 common input port [0649] 148 transversal evaluation unit [0650] 149 multi-wavelength output port [0651] 150 longitudinal evaluation unit [0652] 152 position information [0653] 154 data processing device [0654] 156 transformation unit [0655] 158 substrate [0656] 160 first electrode [0657] 162 blocking layer [0658] 164 n-semiconducting metal oxide [0659] 166 dye [0660] 168 p-semiconducting organic material [0661] 170 second electrode [0662] 172 encapsulation [0663] 174 electrode contact [0664] 176 partial electrode [0665] 178 partial electrode, x [0666] 180 partial electrode, y [0667] 182 contact leads [0668] 184 light spot [0669] 186 image [0670] 188 electrically conductive polymer [0671] 190 top contact [0672] 192 illumination source [0673] 194 focal point [0674] 196 human-machine interface [0675] 198 entertainment device [0676] 199 tracking system [0677] 200 user [0678] 201 track controller [0679] 202 machine [0680] 204 beacon device [0681] 206 primary light beam [0682] 208 display [0683] 210 keyboard