SPECTROMETER AND METHOD FOR ANALYZING A LIGHT SAMPLE USING A SPECTROMETER

Abstract

A spectrometer including at least one light-coupling element, a variable entrance slit, a dispersive element, a detector element and a control and evaluation unit. The object of providing a spectrometer having improved measuring characteristics is achieved in that the variable entrance slit is implemented by a first spatial modulation element including a plurality of pixels, wherein the individual pixels can be arranged independently of one another by the control and evaluation unit, wherein the individual pixels are arranged in order to implement the entrance slit during operation in such a manner that at least part of the light incident from the light-coupling element is passed on to the dispersive element.

Claims

1. A spectrometer comprising: at least one light-coupling element; a variable entrance slit; a dispersive element; a detector element; and a control and evaluation unit, wherein the variable entrance slit is implemented by a first spatial modulation element comprising a plurality of pixels, wherein the individual pixels can be arranged independently of one another by the control and evaluation unit, wherein the individual pixels are arranged in order to implement the entrance slit during operation in such a manner that at least part of the light incident from the light-coupling element is passed on to the dispersive element.

2. The spectrometer according to claim 1, wherein the first spatial modulation element is configured as a first micro-mirror array, wherein the plurality of pixels are implemented by a plurality of micro-mirrors.

3. The spectrometer according to claim 1, wherein the at least one light-coupling element is designed as an optical waveguide or as an optical waveguide bundle.

4. The spectrometer according to claim 1, wherein the first spatial modulation element is located on the optical path in front of the dispersive element and, furthermore, between the dispersive element and the detector element, the pixels are arranged in a first partial region of the first spatial modulation element that, during operation, the light incident from the light-coupling element is at least partially transmitted to the dispersive element, and that the pixels are arranged in a second partial region of the first spatial modulation element that, during operation, the spectral components of the light sample to be examined are sequentially directed onto the detector element.

5. The spectrometer according to claim 1, characterized in that a second spatial modulation element comprising a plurality of pixels is provided, wherein each pixel can be separately arranged by the control and evaluation unit, wherein the second spatial modulation element is arranged on the optical path between the dispersive element and the detector element, wherein the control and evaluation unit deflects the plurality of pixels of the second spatial modulation element during operation such that the spectral components of the light sample to be examined are sequentially deflected onto the detector element.

6. The spectrometer according to claim 1, wherein the detector element is configured as an individual detector.

7. A method for analyzing a light sample using a spectrometer, wherein the spectrometer has at least one light-coupling element, a variable entrance slit, a dispersive element, a detector element and a control and evaluation unit, the method comprising: implementing the variable entrance slit by a first spatial modulation element comprising a plurality of pixels, wherein the individual pixels can be arranged independently of one another by the control and evaluation unit, wherein the individual pixels are arranged in order to implement the entrance slit during operation for at least part of the light incident from the light-coupling element is passed on to the dispersive element, wherein the width of the entrance slit is varied depending on the measurement situation before or during a measurement, the light sample to be analyzed is separated by the dispersive element into its spectral components, the spectral components of the light sample are imaged onto the detector element, and the control and evaluation unit determines the spectrum of the light sample.

8. The method according to claim 7, wherein at least before the spectrometer is put into operation, the image of the light-coupling element is scanned by bringing the individual pixels of the first spatial modulation element into the ON position one after the other, wherein the ON position designates the position in which a pixel transmits the light to be analyzed to the dispersive element, and wherein, at the same time, the intensity of the light transmitted by the respective pixel is detected at the detector element.

9. The method according to claim 7, wherein the slit shape of the entrance slit is varied depending on the measurement situation before or during a measurement by the slit width being separately set line by line.

10. The method according to claim 7, wherein the slit width or the slit shape of the entrance slit is varied during operation depending on the spectral component of the light sample to be examined, which falls on the detector element.

11. The method according to claim 7, wherein the light-coupling element is configured as an optical waveguide bundle comprising linearly arranged optical waveguides, that the pixels of the first spatial modulator are preferably arranged line by line in such a manner that a deviation of individual optical waveguides from the linear arrangement is corrected.

12. The method according to claim 12, wherein the image of the optical waveguide bundle is trimmed by arranging the pixels into a column shape for correction.

13. The method according to claim 12, wherein the shape of the entirety of the pixels of the first spatial modulator which transmit the light into the spectrometer is adapted to the shape of the image of the optical waveguide bundle for correction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] FIG. 1 a first embodiment of a spectrometer according to the invention,

[0060] FIG. 2 a second embodiment of a spectrometer according to the invention,

[0061] FIG. 3 a third embodiment of a spectrometer according to invention,

[0062] FIG. 4 an embodiment of an image of an optical waveguide bundle on a first micro-mirror array,

[0063] FIG. 5 another embodiment of an image of an optical waveguide bundle on a first micro-mirror array

[0064] FIG. 6 another embodiment of a spectrometer according to the invention,

[0065] FIG. 7 another embodiment of an image on the first micro-mirror array, and

[0066] FIG. 8 a first embodiment of a method according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0067] FIG. 1 shows a first embodiment of a spectrometer 1 with a light-coupling element 3 in the form of a glass fiber, with a variable entrance slit 4 formed by a first spatial modulation element in the form of a first micro-mirror array 5, with a dispersive element 6 formed as a reflecting diffraction grating, with a detector element 7 and with a control and evaluation unit 8. The individual micro-mirrors of the micro-mirror array 5 can each be arranged separately by applying a voltage through the control and evaluation unit 8. During operation, the individual mirrors are deflected in such a manner that at least part of the light incident via the glass fiber is imaged onto the detector element 7 via an optical path. In addition to these elements, the optical path also has optical lenses 9 for beam shaping and focusing of the light sample to be examined

[0068] A second embodiment of a spectrometer 1 is shown in FIG. 2, wherein, in contrast to the spectrometer 1 shown in FIG. 1, a second spatial modulation element in the form of a second micro-mirror array 10 is located between the dispersive element 6 and the detector 7, which can also be controlled by the control and evaluation unit 8. The control and evaluation unit 8 deflects the plurality of the micro-mirrors of the second micro-mirror array 10 during operation in such a manner that the spectral components of the light sample to be examined separated by the diffraction grating are sequentially deflected onto the detector element 7. In the embodiment shown, the detector element 7 is designed as a single detector. The shown configuration has the advantage that no overlapping of the diffraction maxima of different wavelengths occurs or is detected during the acquisition of the individual spectral components, whereby the accuracy of the spectrometer is particularly high. This embodiment also has the advantage that the slit width of the entrance slit 4 can also be adjusted during a measurement depending on the spectral component of the light sample to be examined currently hitting the detector element 7.

[0069] In the embodiment of a spectrometer 1 shown in FIG. 3, the light-coupling element 3 is designed as a glass fiber bundle, wherein the individual glass fibers are positioned linear to each other. The image of this glass fiber bundle is directed through an imaging optic onto the first micro-mirror array 5. What is shown is a micro-mirror array 5 and a part of the micro-mirrors. The individual mirrors of the micro-mirror array 5 are arranged in such a manner that a column-shaped part of the image of the glass fiber bundle is transmitted to the spectrometer. A column-shaped part of the micro-mirrors is arranged in the ON position 14. The remaining part of the micro-mirrors reflects the incident light in the OFF position 15 away from the dispersive element 6. The slit width is selected so that all mirrors arranged in the ON position are essentially fully illuminated and that the spectrometer 1 is optimized overall with regard to luminous efficacy and resolution.

[0070] FIG. 4 shows an embodiment of an image of an optical waveguide bundle on a first micro-mirror array 5. In the embodiment shown, an optical waveguide is positioned offset to the other optical waveguides, deviating from the linear arrangement. This faulty positioning can be corrected during operation in that the light-transmitting slit, i.e. the micro-mirrors arranged in the ON position 14, are positioned in such a manner that all micro-mirrors are essentially fully illuminated despite the offset arrangement. In this manner, the complete image of the glass fiber bundle can be trimmed so that a deviation of individual optical fibers from the linear positioning is corrected with respect to transmission into the spectrometer. The slit width in the embodiment shown corresponds to the width of a micro-mirror. In addition, the slit width can, of course, also include several micro-mirrors and can be adapted to the measurement situation, especially during operation.

[0071] FIG. 5 shows another embodiment of an image of an optical waveguide bundle on a first micro-mirror array 5, wherein an optical waveguide is also positioned offset to the other optical waveguides in a manner that deviates from the linear positioning. In contrast to the illustration shown in FIG. 4, this faulty positioning is corrected in that the micro-mirrors, which are arranged in the ON position 14, are also arranged line by line with the other micro-mirrors arranged in the ON position 14 in the area of the image of the offset light-wave light guide. As a result, the shape of the micro-mirrors arranged in the ON position 14 is adapted to the shape of the image of the optical fiber bundle.

[0072] FIG. 6 shows another embodiment of a spectrometer 1. The first micro-mirror array 5 is positioned in such a manner that it is located in the beam path on the one hand in front of the dispersive element 6 and on the other hand between the dispersive element 6 and the detection element 7. The course of the beam path is indicated by arrows on the illustrated light beams.

[0073] In detail, a first partial region 17 of the micro-mirror array 5 implements the function of the entrance slit 4 and a second partial region 18 implements the function transmitting individual spectral components to the detection element 7. For this, the light to be analyzed is focused on the second partial region 18 of the micro-mirror array 5 by means of a confocal mirror 16.

[0074] FIG. 7 shows the image of the light to be analyzed on the micro-mirror array 5 according to the arrangement shown in FIG. 6. The illustration shows a first partial region 17, which implements the function of an entrance slit 4, and a second partial region 18, which directs the spectral components onto the detection element 7.

[0075] Alternative embodiments show a liquid crystal display or a switchable grating as the first and/or second spatial modulation element otherwise having the same design of the spectrometer as shown in FIGS. 1 to 7.

[0076] FIG. 8 shows an embodiment of a method 2 for analyzing a light sample, wherein the spectrometer 1 is designed according to the embodiment shown in FIG. 2. First, when the spectrometer is put into operation, the image of the light-coupling element is scanned to determine the orientation of the micro-mirrors of the first micro-mirror array 5. Depending on the scanned image and on the measuring situation, the micro-mirrors are arranged in the ON position 14 or in the OFF position 15.

[0077] In a first step 11 of the method 2, the light sample to be examined is now coupled into the spectrometer 1 via the light-coupling element 3. Via the first micro-mirror array 5, the incident light is transmitted in the form of a slit with a defined slit width to the dispersive element 6 and broken down into its spectral components by the dispersive element 6. Furthermore, the individual spectral components are imaged 12 sequentially onto the detector element by deflecting the individual mirrors of the second micro-mirror array 10. The slit width of the entrance slit 4 is adapted by the control and evaluation unit 8 13 to the spectral component currently hitting the detector element 7. Finally, the control and evaluation unit 8 determines 14 the spectrum of the light sample to be examined

[0078] The illustrated method 2 has the advantage that an optimization with regard to the resolution of spectrometer 1 and the luminous efficacy, i.e. the amount of light transmitted into spectrometer 1, can be carried out particularly precisely, especially during a measurement.