DE102016212088A1 - Device for limiting an angle of incidence for a spectrometer and method for operating such a device - Google Patents

Abstract

The invention relates to a device (100) for limiting an angle of incidence (102) for a spectrometer, wherein the device (100) has a focusing element (104) for focusing a light (116) incident on a spectral element downstream of the device (100) a focus (112), an aperture element (108), and a directing element (106) for directing the light (116) focused within an aperture (110) of the aperture element (108), the aperture element (108) being in the area of focus (11); 112) is disposed on an optical axis (114) between the focusing element (104) and the directing element (106).

Description

State of the art

The invention is based on a device or a method according to the preamble of the independent claims. The subject of the present invention is also a computer program.

The DE 1968 1285 T1 describes an accessory for an infrared microspectrometer.

Disclosure of the invention

Against this background, with the approach presented here, a device for limiting an angle of incidence for a spectrometer, furthermore a method which uses this device, and finally a spectrometer according to the main claims are presented. The measures listed in the dependent claims advantageous refinements and improvements of the independent claim device are possible.

A Fabry-Pérot interferometer (FPI) acts as a filter that passes only a narrow band around a resonance wavelength. In a micromechanical Fabry-Pérot interferometer, a distance between two mirror elements can determine the resonance wavelength and its overtones. By varying the distance, the desired resonance wavelength can be adjusted. In a subsequent detector, an intensity of the transmission is measured and so serially recorded a spectrum.

In Fabry-Pérot interferometers, a variation of the angle of incidence of the light beam causes a shift in the wavelength to be measured. The approach presented here prevents light beams with different angles of incidence from arriving simultaneously on the Fabry-Pérot interferometer filter.

The invention relates to a device for limiting an angle of incidence for a spectrometer, the device comprising a focusing element for focusing a light incident on a spectral element of the spectrometer downstream of the device onto a focus, an aperture element and a steering element within a diaphragm aperture of the spectrometer Aperture element focused light (for example, the spectral element) of the spectrometer, wherein the aperture element is arranged in the region of the focus on an optical axis between the focusing element and the guiding element. The directing element can also collimate the beam.

By a spectral element, a Fabry-Pérot interferometer can be understood. The spectral element can be arranged downstream in a beam path of the spectrometer of the device. A focus can be a computational focus.

The focusing element and / or the guiding element may be an optical lens. Lenses result in a rectilinear beam path and the optical axis has no offset.

The focusing element and / or the guiding element may be a mirror. Mirrors can avoid aberrations. Mirror elements are easy to produce. Mirrors can be produced, for example, as a free-form surface by injection molding and subsequent application of a reflective layer.

The focusing element and / or the guiding element may at least partially be a section of a concave mirror. In particular, the concave mirror can be a parabolic mirror with a defined focus.

The aperture element may be a pinhole. The diaphragm member may have a through hole for the collimated light. A pinhole is easy to produce.

The diaphragm element may be at least partially a light guide. An optical fiber may be, for example, fiberglass or plastic fiber. A light guide can be bent and alternatively or additionally transport the light over a greater distance with virtually no attenuation. As a result, the focusing element and the guiding element can be arranged spatially separated.

The optical axis may be oriented transversely to the incident light. An optical axis aligned transversely to the incident light may be understood to mean an alignment of the optical axis which is not aligned parallel, in particular at right angles to the incident light. By a kink in the optical path, a low height can be achieved.

Furthermore, a spectrometer is presented with a device according to the approach presented here, wherein the device is preceded by a spectral element of the spectrometer and a photodetector of the spectrometer and the steering element is aligned to direct light onto the spectral element.

For example, a spectral element may have two mirror elements whose spacing is changeable to influence a resonance wavelength. A photodetector is configured to image an intensity of light in an electrical signal.

The spectrometer may comprise at least one further device according to the approach presented here. The further device may be arranged adjacent to the device. Multiple devices can deliver more light to the spectrometer than a single device. The devices may be arranged around the spectral element.

The spectrometer may have a light source. The light source may be configured to emit light substantially opposite to an incident direction of the focusing element for light. The light source may be a diode. The light source can emit light of a certain wavelength. The light source can be arranged on the axis of symmetry. This avoids parallax errors such as oblique illumination.

The light source and the photodetector can be arranged on a (for example flexible) contacting device. The contacting device can in particular be bent around the device. By a common contacting a production can be simplified.

Furthermore, a method for limiting an angle of incidence on a spectrometer is presented, the method comprising the following steps:

Focusing a light incident on the spectrometer to a focus in the region of an aperture element; and

Directing the focused within an aperture of the diaphragm element light on a spectral element of the spectrometer.

Embodiments of the approach presented here are shown in the drawings and explained in more detail in the following description. It shows:

1 an illustration of an apparatus for limiting an angle of incidence with lenses according to an embodiment;

2 a representation of an apparatus for limiting an angle of incidence with mirrors according to an embodiment;

3 an illustration of an apparatus for limiting an angle of incidence with a light guide according to an embodiment;

4 a sectional view through a spectrometer according to an embodiment;

5 a representation of an arrangement of four devices according to an embodiment;

6 Representations of a spectrometer according to an embodiment; and

7 a flowchart of a method for limiting an angle of incidence according to an embodiment.

In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and similar acting, with a repeated description of these elements is omitted.

1 shows a representation of a device 100 for limiting an angle of incidence 102 with lenses 104 . 106 according to an embodiment. The device 100 can be placed in front of a spectral element and a variance of the angle of incidence 102 limit. The device has the first lens 104 as a focusing element 104 and the second lens 106 as a guiding element 106 on. Between the lenses 104 . 106 is an aperture element 108 arranged. The aperture element 108 is designed as a pinhole. An aperture 110 of the diaphragm element 108 is in the range of a focus 112 of the focusing element 104 arranged. The aperture 110 corresponds here to a clear width of a recess of the diaphragm element 108 , The guiding element 106 has the same focus 112 on, like the focusing element 104 , The guiding element 106 is arranged so that both foci 112 are in the same place. This will be parallel to an optical axis 114 the device incident light rays 116 through the first lens 104 in focus 112 to a focal point 118 bundled, pass unimpeded the aperture 110 and are from the second lens 106 again along the optical axis 114 directed.

When the light 116 oblique to the optical axis 114 on the first lens 104 falls, it is also in a focal point 118 bundled. As long as the focal point within the aperture 110 lies, the light happens 116 the aperture device 108 , When the angle of incidence 102 so big is that the focal point 118 outside the aperture 110 lies, absorbs and / or reflects the aperture device 108 the light 116 back again.

In 1 the basic principle of the lens pinhole lens concept is shown. there there is the pinhole 108 advantageous near the plane of the two lens focal points 112 , In this configuration, the directions are input angles 102 the first lens 104 and output angle of the second lens 106 identical. light rays 116 within the acceptance angle are through the pinhole 108 not disabled. Exceed the input angle beams 116 the first lens 104 the acceptance angle, these are no longer the second lens 106 guided. This means at the output of the second lens 106 will only light rays 116 permitted with a maximum output acceptance angle. By adjusting the focal lengths of the first lens 104 to the second lens 106 the light beam intensity per unit area can be changed.

2 shows a representation of a device 100 for limiting an angle of incidence with mirrors 104 . 106 according to an embodiment. The device basically works like the ones in 1 illustrated device. In contrast, the optical elements 104 . 106 as a concave mirror 104 . 106 educated. Here, too, focuses the focusing element 104 along the optical axis 114 incident light 116 in the focus 112 , In focus 112 or in a focal plane is the aperture element 108 with its aperture 110 arranged. The guiding element 106 directs the light 116 again in the direction of the optical axis 114 ,

The mirror 104 . 106 are aligned with each other so that an optical axis between the mirrors 104 . 106 transverse to the optical axis 114 before and after the device 100 is aligned. The light 116 thus points through the device 100 a lateral offset on.

In 2 is a comparable structure with reflectors 104 . 106 listed. This configuration is smaller in height and is expected to be made from a molded part with a subsequent coating.

3 shows a representation of a device 100 for limiting an angle of incidence with a light guide 300 according to an embodiment. The device 100 is essentially the same as in 2 , In contrast, the aperture element 108 here through the light guide 300 formed with a sheath or casing of the light guide. In this case, a diameter of the light-conducting part of the light guide corresponds 300 the aperture 110 , The outside of the light guide 300 on the aperture element 108 striking light 116 does not reach the directing element 106 ,

By using a light guide 300 instead of pinhole, the two reflectors can be 104 . 106 place independently of each other.

4 shows a sectional view through a spectrometer 400 according to an embodiment. The spectrometer 400 includes at least two devices 100 as they are in 2 are shown. The devices 100 limit the variance of the angle of incidence on a spectral element 402 of the spectrometer 400 , The spectral element 402 is on a photodetector 404 arranged. The light 116 that through the devices 100 is achieved using the spectral element 402 filtered. In each case only a specific wavelength or a specific wavelength range penetrates through the spectral element 402 to the photodetector 404 , The photodetector 404 converts an intensity of the incident light 116 in an electrical signal. After the intensity of a wavelength is detected, the spectral element 402 be changed to allow a different wavelength. Thus, with several measurements, a wavelength spectrum of the light 116 to be created.

In one embodiment, the spectrometer includes 400 a light source 406 , Here is the light source 406 designed as a light-emitting diode. The light source 406 is between the devices 100 arranged and aligned so that their emitted light on a target object 408 or target in a detection area 410 of the spectrometer 400 falls. The photodetector 404 , the spectral element 402 , the light source 406 and the coverage area 410 are in an axis of symmetry 412 of the spectrometer 400 aligned.

In one embodiment, the focusing element 104 and the guiding element 106 contrary to the representations in the 1 to 3 shaped differently. This will do this through the aperture 110 falling light 116 over the directing element 106 on the between the two devices 100 arranged spectral element 402 directed. In other words, the devices 100 different angles of incidence and angles of incidence.

In the approach presented here, an adjustment of an angle of incidence range of a to a Fabry-Perot interferometer 402 incident radiation by means of a lens / reflector pinhole arrangement 100 allows. Alternatively, the pinhole 110 be replaced by an optical fiber.

A micromechanical Fabry-Perot interferometer (FPI) 402 may consist of two mirror elements, which are arranged on a substrate over a through hole. It can do that Through hole may be an aperture below the two mirrors, which allows the light to fall on the detector. In addition, an interferometer may be constructed of two substrates with through holes. The light beam is passed vertically through the sandwich design with two highly reflective mirrors, each narrow-band areas are transmitted to a resonance wavelength and their overtones depending on the distance between the two mirrors. By varying the distance, the desired resonance wavelength can be adjusted. In a subsequent detector 404 An intensity of the transmission is measured and so serially recorded a spectrum. An additional bias pass filter can filter out the desired order of wavelength so that errors due to other wavelength orders are minimized. The knowledge of a main angle of incidence can be used to correct a spectral offset.

In an embodiment not shown, the spectrometer 400 an eccentric lighting arrangement. The place of the target 408 reflected light rays 116 be through a mirror or a lens to the pinhole 110 at the location or near the focal point and via another mirror or lens to the spectral element 402 directed. The downstream detector 404 can be the sum of the filtered beams of light 116 detect.

The combination of mirrors 104 or lens 104 , a pinhole 110 near the focal point and another mirror 106 or lens 106 allows a concentration of light rays 116 by choosing different focal lengths to maximize the intensity on the detector 404 ,

By tilting the optical axes of the two mirrors 104 . 106 or lenses 104 . 106 can the light 116 saves space through the interferometer 402 to the detector 404 be directed. The resulting wave spectrum error due to the incident angle offset can be compensated by calibration.

In 4 a possible construction is shown in which an advantageous axisymmetric illumination is present. Here is an illumination axis 412 equal to a detector axis 412 , In the configuration shown here are the surfaces of the two reflectors 104 . 106 rotated in opposite directions around the focal point, so that the input angle of the first reflector 104 different from the output angle of the second reflector 106 is. This is advantageous to make optimal use of the space.

The structure can be used analogously, if this along the optical axis 412 halved. However, with this eccentric illumination, the need for calibration and compensation is higher because of the spot 406 not concentric with the detector axis 412 illuminated at different target intervals.

5 shows a representation of an arrangement 500 of four devices 100 according to an embodiment. The order 500 corresponds essentially to the arrangement in 4 , In contrast, the steering elements are here by a housing 502 covered. The devices 100 are arranged in a cross shape and each rotated by 90 ° to each other. The housing 502 has four side surfaces, which through the four panel elements 108 are formed. On a square ceiling surface, a light source can be arranged.

It becomes a geometric contour 100 presented, in which the variance of the angle of incidence to the optical axis or the surface normal of the resonator mirror of the spectral element 402 minimized and at the same time the target 408 reflected spectral wavelength intensity on the detector surface 404 is maximized. The mean value of the angles of incidence can be suitably calibrated.

Through the pinhole 108 Light rays are reflected or absorbed outside of the internal space, so that only very few misdirected light beams with different angles of incidence can hit the interferometer-detector combination.

In 5 is an advantageous construction 500 shown at the four reflector 104 - pinhole 108 - Reflector combinations 100 are symmetrically arranged and take advantage of a square base very well. The structure 500 can also have more than four segments. The lighting can be on the middle pedestal 502 be placed in the center, so that an axisymmetric structure is possible.

When the number of reflector pinhole reflector combinations 100 is chosen to be very large around the optical axis, a concentric radial light guide is possible by a circumferential pin hole slot.

6 shows representations of a spectrometer 400 according to an embodiment. The spectrometer 400 is shown in a sectional view and a plan view. The spectrometer 400 is essentially the same as in 4 , In addition, here is a contacting device 600 for electrically contacting the spectral element 402 , the photodetector 404 and the light source 406 shown. The contacting device 600 has a flexible circuit board 602 with a stiffening element 604 on. The spectral element 402 , the photodetector 404 and the arrangement 500 are on the stiffening element 604 arranged. The order 500 essentially corresponds to the arrangement in 5 , In addition, the devices are 100 here united to a component. The light source 406 is on a finger 606 the flexible circuit board 602 arranged, which is bent by 180 ° and on the ceiling surface of the arrangement 500 is arranged. Here is the light source 406 on the same side of the circuit board 602 arranged as the stiffening element 604 , The light source 406 emits their light through a breakthrough of the circuit board 602 , The finger 606 runs over a bridge between two devices 100 ,

In other words shows 6 a component 400 as a miniature spectrometer 400 is formed, wherein the component 400 a light source 406 , a light guide 100 with a limitation of the incident angle variances on a spectral element 402 and a photodetector 404 includes.

Here is the light guide 100 from several different segments to the intensity on the detector 404 to maximize. The light guide 100 consists of reflectors or lens geometries, which can be constructed of continuous surfaces or as Fresnel.

In one embodiment, the spectral element is 402 a micromechanical Fabry-Pérot interferometer component, which has at least one substrate and two spaced-apart mirror elements spaced apart by a gap.

In 6 is a possible lighting contact 600 with a flexlead 602 shown. Additional struts between the reflectors can increase the stability of the construction 500 Increase and appropriate cooling of the lighting 406 to ensure.

7 shows a flowchart of a method 700 for limiting an angle of incidence according to an embodiment. The procedure can also be used as a procedure 700 for operating a variant of a device mentioned above 100 be understood. The method has one step 701 focusing and one step 702 of steering. In step 701 In the case of focusing, a light incident on a spectrometer is focused onto a focus in the region of an aperture element. In step 702 of the steering, the focused within an aperture of the diaphragm element light is directed to a spectral element of the spectrometer.

If an exemplary embodiment comprises a "and / or" link between a first feature and a second feature, then this is to be read so that the embodiment according to one embodiment, both the first feature and the second feature and according to another embodiment either only first feature or only the second feature.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19681285 T1 [0002]

Claims (12)

Contraption ( 100 ) for limiting an angle of incidence ( 102 ) for a spectrometer ( 400 ), the device ( 100 ) a focusing element ( 104 ) for focusing on one of the devices ( 100 ) downstream spectral element ( 402 ) incident light ( 116 ) to a focus ( 112 ), an aperture element ( 108 ) and a guiding element ( 106 ) for steering the inside of an aperture ( 110 ) of the diaphragm element ( 108 ) focused light ( 116 ), wherein the diaphragm element ( 108 ) in the area of focus ( 112 ) on an optical axis ( 114 ) between the focusing element ( 104 ) and the guiding element ( 106 ) is arranged. Contraption ( 100 ) according to claim 1, wherein the focusing element ( 104 ) and / or the directing element ( 106 ) is an optical lens. Contraption ( 100 ) according to one of the preceding claims, in which the focusing element ( 104 ) and / or the directing element ( 106 ) is a mirror. Contraption ( 100 ) according to claim 3, wherein the focusing element ( 104 ) and / or the directing element ( 106 ) is at least partially a portion of a concave mirror. Contraption ( 100 ) according to one of the preceding claims, in which the diaphragm element ( 108 ) is a pinhole. Contraption ( 100 ) according to one of claims 1 to 4, in which the diaphragm element ( 108 ) at least partially a light guide ( 300 ). Contraption ( 100 ) according to one of the preceding claims, in which the optical axis ( 114 ) transverse to the incident light ( 116 ) is aligned. Spectrometer ( 400 ) with a device ( 100 ) according to one of the preceding claims, wherein the device ( 100 ) a spectral element ( 402 ) of the spectrometer ( 400 ) and a photodetector ( 404 ) of the spectrometer ( 400 ) and the directing element ( 106 ) is aligned to transmit light to the spectral element ( 402 ) to steer. Spectrometer ( 400 ) according to claim 8, with at least one further device ( 100 ) according to one of claims 1 to 7, wherein the further device ( 100 ) adjacent to the device ( 100 ) is arranged. Spectrometer ( 400 ) according to one of the preceding claims, with a light source ( 406 ), in particular wherein the light source ( 406 ) is adapted to light substantially opposite to an incident direction of the focusing element ( 104 ) to emit light. Spectrometer ( 400 ) according to claim 10, wherein the light source ( 406 ) and the photodetector ( 404 ) on a contacting device ( 600 ) are arranged, in particular wherein the contacting device ( 600 ) around the device ( 100 ) is bent around. Procedure ( 700 ) for operating a device ( 100 ) according to one of the preceding claims for limiting an angle of incidence ( 102 ) for a spectrometer ( 400 ), the method comprising the following steps: focusing ( 701 ) one on the spectral element ( 402 ) of the spectrometer ( 400 ) incident light ( 116 ) to a focus ( 112 ) in the region of an aperture element ( 108 ); and steering ( 702 ) within a diaphragm aperture ( 110 ) of the diaphragm element ( 108 ) focused light ( 116 ) to a spectral element ( 402 ) of the spectrometer ( 400 ).

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