METHOD FOR PRODUCING A HOLOGRAPHIC OPTICAL ELEMENT (HOE), WHICH IS PROVIDED FOR PROJECTION IN A PROJECTION SYSTEM, A HOLOGRAPHIC OPTICAL ELEMENT OF THIS KIND, PROJECTION DEVICE, LENS FOR DATA GLASSES AND DATA GLASSES OF THIS KIND

Abstract

A method for producing a holographic optical element (HOE) that is provided for projection in a projection system. A hologram is recorded by the fact that a first Gaussian beam and a second Gaussian beam are caused to interfere on a holographic film for at least two different configurations. The first Gaussian beam is a reference beam that, for the at least two different configurations, is identical to a reconstruction beam with which the HOE is reconstructed. The second Gaussian beam is furthermore an object beam that, upon reconstruction of the HOE utilizing the reconstruction beam, is identical to a projection beam that is used in the projection system for projection. For the at least two different configurations, at least one beam property that depends respectively on predefined projection properties of the projection system is predefined for the second Gaussian beam.

Claims

1-12. (canceled)

13. A method for producing a holographic optical element (HOE) that is provided for projection in a projection system, the method comprising: recording a hologram by causing a first Gaussian beam and a second Gaussian beam to interfere on a holographic film for at least two different configurations, the first Gaussian beam being a reference beam that, for the at least two different configurations, is identical to a reconstruction beam with which the HOE is reconstructed, and the second Gaussian beam being an object beam that, upon reconstruction of the HOE utilizing the reconstruction beam, is identical to a projection beam that is used in the projection system for projection, and wherein, for the at least two different configurations, at least one beam property that depends respectively on predefined projection properties of the projection system is predefined for the second Gaussian beam.

14. The method as recited in claim 13, wherein the at least one beam property is a propagation direction, or a size of a beam waist, or a position of the beam waist.

15. The method as recited in claim 13, wherein a quality function for the second Gaussian beam is optimized.

16. The method as recited in claim 15, wherein the quality function is a weighted summing function that has, for the at least two different configurations and for a respective predefined location between the HOE and a projection surface, a respective summand that is a variable derived from the at least one beam property.

17. The method as recited in claim 13, wherein the hologram is a reflection hologram or encompasses a reflection hologram.

18. The method as recited in claim 13, wherein the holographic film is flat or curved.

19. A holographic optical element that includes a recorded hologram, the hologram being recorded by causing a first Gaussian beam and a second Gaussian beam to interfere on a holographic film for at least two different configurations, the first Gaussian beam being a reference beam that, for the at least two different configurations, is identical to a reconstruction beam with which the HOE is reconstructed, and the second Gaussian beam being an object beam that, upon reconstruction of the HOE utilizing the reconstruction beam, is identical to a projection beam that is used in the projection system for projection, and wherein, for the at least two different configurations, at least one beam property that depends respectively on predefined projection properties of the projection system is predefined for the second Gaussian beam.

20. A projection apparatus for a set of data glasses, the projection apparatus comprising: a light source configured to emit a light beam; a holographic optical element (HOE) disposed or disposable on an eyeglass lens of the data glasses to project an image onto a retina of a user of the data glasses by deflecting the light beam toward an ocular lens of the user and/or by focusing the light beam; and a beam deflection element configured to reflect the light beam onto the HOE.

21. The projection apparatus as recited in claim 20, wherein the HOE is a holographic optical element that includes a recorded hologram, the hologram being recorded by causing a first Gaussian beam and a second Gaussian beam to interfere on a holographic film for at least two different configurations, the first Gaussian beam being a reference beam that, for the at least two different configurations, is identical to a reconstruction beam with which the HOE is reconstructed, and the second Gaussian beam being an object beam that, upon reconstruction of the HOE utilizing the reconstruction beam, is identical to a projection beam that is used in the projection system for projection, and wherein, for the at least two different configurations, at least one beam property that depends respectively on predefined projection properties of the projection system is predefined for the second Gaussian beam.

22. An eyeglass lens for a set of data glasses, wherein a holographic optical element (HOE) is disposed on a surface of the eyeglass lens, the HOE including a recorded hologram, the hologram being recorded by causing a first Gaussian beam and a second Gaussian beam to interfere on a holographic film for at least two different configurations, the first Gaussian beam being a reference beam that, for the at least two different configurations, is identical to a reconstruction beam with which the HOE is reconstructed, and the second Gaussian beam being an object beam that, upon reconstruction of the HOE utilizing the reconstruction beam, is identical to a projection beam that is used in the projection system for projection, and wherein, for the at least two different configurations, at least one beam property that depends respectively on predefined projection properties of the projection system is predefined for the second Gaussian beam.

23. A set of data glasses having at least one eyeglass lens, wherein a holographic optical element (HOE) is disposed on a surface of the eyeglass lens, the HOE including a recorded hologram, the hologram being recorded by causing a first Gaussian beam and a second Gaussian beam to interfere on a holographic film for at least two different configurations, the first Gaussian beam being a reference beam that, for the at least two different configurations, is identical to a reconstruction beam with which the HOE is reconstructed, and the second Gaussian beam being an object beam that, upon reconstruction of the HOE utilizing the reconstruction beam, is identical to a projection beam that is used in the projection system for projection, and wherein, for the at least two different configurations, at least one beam property that depends respectively on predefined projection properties of the projection system is predefined for the second Gaussian beam.

24. The set of data glasses as recited in claim 23, further comprising: a projection apparatus including: a light source configured to emit a light beam; and a beam deflection element configured to reflect the light beam onto the HOE.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Exemplifying embodiments of the present invention are depicted in the figures and are explained in further detail in the description below.

[0041] FIG. 1A shows a recording of a spherical wave deflector of the related art

[0042] FIG. 1B shows a reconstruction of a spherical wave deflector of the related art.

[0043] FIGS. 2A, 2B, and 2C show the deflection behavior of a spherical wave deflector for the case in which a Gaussian beam is incident onto the spherical wave deflector.

[0044] FIG. 3 is a schematic flow chart of a method in accordance with an exemplifying embodiment of the present invention.

[0045] FIG. 4 shows an assemblage for recording an HOE, in accordance with an exemplifying embodiment of the present invention.

[0046] FIG. 5 shows a reconstruction of the HOE whose production is illustrated in FIG. 4.

[0047] FIG. 6 shows an assemblage for recording an HOE, in accordance with a further embodiment of the present invention.

[0048] FIG. 7 shows a reconstruction of the HOE whose production is illustrated in FIG. 6.

[0049] FIG. 8 schematically depicts a projection apparatus in accordance with an example embodiment of the present invention.

[0050] FIG. 9 is a schematic isometric depiction of a set of data glasses in accordance with an example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0051] FIG. 1 shows in sub-FIG. 1A the recording, and in sub-FIG. 1B the reconstruction or playback, of an HOE, in particular a deflection HOE, in the present case a spherical wave deflector of the related art. Sub-FIG. 1A shows a holographic film 200 on which the light sources of two spherical waves are caused to interfere. First spherical wave 204 is divergent, is emitted from point 202, and is incident from the right (in the view of sub-FIG. 1A) onto holographic film 200. Second spherical wave 208 is convergent and is incident from the left (in the view of sub-FIG. 1A) onto holographic film 200 and, without holographic film 200, would be focused onto point 206. An interference pattern, from which HOE 210, in particular the deflection HOE or spherical wave deflector 211, is created is therefore recorded on holographic film 200.

[0052] Sub-FIG. 1B depicts the manner in which convergent spherical wave 208 is reconstructed with the aid of divergent spherical wave 204 which is now incident onto the completed HOE 210, in particular the deflection HOE.

[0053] FIGS. 2A-2C show the manner in which spherical wave deflector 211 according to the related art serves locally as a deflection element for an incident Gaussian beam.

[0054] FIG. 2A shows the manner in which a Gaussian beam that, in the view of FIG. 2A (which is identical to the views of FIGS. 1A and 1B), is incident at the very top onto spherical wave deflector 211, becomes diffracted at point 206. FIG. 2B shows the manner in which a Gaussian beam that is incident onto spherical wave deflector 211 at the center becomes diffracted at point 206. FIG. 2C shows the manner in which a Gaussian beam that is incident at the very bottom onto spherical wave deflector 211 becomes diffracted at point 206. The diffraction at the holographic layer of spherical wave deflector 211 furthermore results in the overlaying of additional phase terms that, in some circumstances, result in a deviation of the propagation behavior from free-space propagation over a comparable distance. This can cause important beam parameters, for instance the radius and location of the beam waist, to be influenced by spherical wave deflection 211 in addition to free-space propagation, which can result in considerable deviations from the expected system properties.

[0055] FIG. 3 shows a method 300 for producing a holographic optical element (HOE) that is provided for projection in a projection system, in accordance with an example embodiment of the present invention.

[0056] In the first step 310, the beam properties that must be possessed by a projection beam which is used for the stipulated projection system are ascertained. In the present case, the beam property of rotational symmetry is optimized. A second Gaussian beam deflected by HOE 210, which is also called an “object beam,” is identical to the projection beam for the different configurations that are used.

[0057] In the next step 320, a quality function for the second Gaussian beam is optimized in order to adapt the second Gaussian beam to the projection system. The quality function is a weighted summing function that has, for the different configurations and for a respective predefined location between HOE 210 and a projection surface, a respective summand that is an indicator of the ellipticity of the respective beam. The necessary beam properties of the second Gaussian beam for the different configurations are obtained from the optimization.

[0058] In the next step 330, a reflection hologram is recorded by the fact that a first Gaussian beam and a second Gaussian beam are caused to interfere, for the different configurations, on a flat holographic film, the first Gaussian beam and the second Gaussian beam being radiated onto the film from different sides.

[0059] The first Gaussian beam is a reference beam that, for the different configurations, is identical to a reconstruction beam with which HOE 210 is reconstructed in the projection system.

[0060] FIG. 4 shows the manner in which, for three different configurations, a first Gaussian beam 212 and a second Gaussian beam 214 are caused to interfere on holographic film 200 with the result that a hologram, HOE 210, in particular a deflection HOE, is recorded.

[0061] Both first Gaussian beam 212 and the second Gaussian beam are generated with the aid of a laser beam source 104 that is firstly collimated by way of a collimator 114 and then focused with the aid of a lens 115 of suitable focal length. Further optics, which are not depicted in the present case, may be necessary in order to correspondingly prepare the beam parameters of first Gaussian beam 212. With no limitation of generality, it can be assumed that one skilled in the art can experimentally modify and define the necessary beam parameters of first Gaussian beam 212 or of second Gaussian beam 214.

[0062] First Gaussian beam 212 is a reference beam that, for the three different configurations, is identical to a reconstruction beam 216 with which the HOE is reconstructed in the projection system. The reconstruction beam is shown in FIG. 5, which will be explained below. First Gaussian beam 212 can have different beam properties for the three different configurations.

[0063] Second Gaussian beam 214 is an object beam that, in the context of the reconstruction of HOE 210 utilizing reconstruction beam 216, is identical to a projection beam 218 that is used for projection in the projection system. Second Gaussian beam 214 can have different beam properties for the three different configurations.

[0064] For the three different configurations, the beam properties predefined for second Gaussian beam 214 or for projection beam 218 are the beam waist and the position thereof. These beam properties of projection beam 218 depend on the predefined projection properties of the projection system.

[0065] In the first configuration of first Gaussian beam 212 and of second Gaussian beam 214, first Gaussian beam 212 and second Gaussian beam 214 are incident onto holographic film 200 at a first location 220. In the second configuration of first Gaussian beam 212 and of second Gaussian beam 214, first Gaussian beam 212 and second Gaussian beam 214 are incident onto holographic film 200 at a second location 222. In the third configuration of first Gaussian beam 212 and of second Gaussian beam 214, first Gaussian beam 212 and second Gaussian beam 214 are incident onto holographic film 200 at a third location 224. Sub-holograms are thus recorded at first location 220, at second location 222, and at third location 224. After recording of the three sub-holograms, the completed HOE 210 exists.

[0066] FIG. 5 shows the manner in which HOE 210, whose recording was explained with reference to FIG. 4, is played back or reconstructed. First Gaussian beam 212 that was used in the context of the recording of HOE 210 is identical to reconstruction beam 216 that is illustrated in FIG. 5. If reconstruction beam 216 is incident onto HOE 210, it becomes deflected by HOE 210 into a projection beam 218 that is identical to second Gaussian beam 214 that was used to record HOE 210. This applies to all three configurations.

[0067] HOE 210 of FIG. 5 has the advantage, as compared with HOE 210 of FIG. 2A, 2B, or 2C, that projection beam 218 is rotationally symmetrical.

[0068] FIG. 6 corresponds substantially to FIG. 4. The three configurations of first Gaussian beam 212 differ, however, in that they have been generated by one and the same laser beam, by the fact that the laser beam that was emitted from laser beam source 104, collimated by collimator 114, and focused by lens 115 is deflected differently by a scannable beam deflection element 226. The three configurations of second Gaussian beam 214 are likewise generated by a single laser beam source 104, by the fact that laser beam source 104, along with collimator 114 and lens 115, is pivoted around point 206. This is indicated by arrow P in FIG. 6.

[0069] FIG. 7 shows a reconstruction or playback of the HOE 210 that was obtained by way of the method explained in FIG. 6.

[0070] FIG. 8 schematically shows the manner of operation of projection apparatus 100. A light beam 106 emitted from a laser diode constituting light source 104 is collimated by a lens constituting collimation element 114 and directed toward a micromirror constituting reflection element 112. Reflection element 112 deflects the light toward deflection element 102 embodied as an HOE. Deflection element 102 is applied onto an eyeglass lens 402. Light beam 106 deflected by deflection element 102 is then incident onto the eye and onto an ocular lens 108, from which light beam 106 becomes focused onto retina 110 of an eyeball 107 of a user.

[0071] Light source 104 is disposed in a housing 105 fastened on eyeglass frame 120. Collimation element 114 is disposed at the output of housing 105. Light source 104, collimation element 114, and reflection element 112 can be accommodated in a shared housing (not depicted), light beam 106 reflected from reflection element 112 being coupled out through a window disposed on one side of the housing. This housing can be fastened on eyeglass temple 118 or on eyeglass frame 120.

[0072] FIG. 9 schematically depicts a set of data glasses 400 having a projection apparatus 100 in accordance with an exemplifying embodiment. Projection apparatus 100 has a scanner optical system 152 and deflection element 102. Scanner optical system 152 is disposed in housing 105 and transmits a light beam 106 (not depicted) through exit window 148 onto deflection element 102. Data glasses 400 have an eyeglass lens 402 on which deflection element 102 is disposed. Deflection element 102 is implemented, for example, as part of eyeglass lens 402. Alternatively, deflection element 102 is implemented as a separate element and is connected to eyeglass 402 using a suitable joining method.