CN107576394B

CN107576394B - Device for defining an angle of incidence on a spectrometer and method for operating the device

Info

Publication number: CN107576394B
Application number: CN201710533700.0A
Authority: CN
Inventors: E.鲍姆加特; R.诺尔特迈尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-07-04
Filing date: 2017-07-03
Publication date: 2021-07-06
Anticipated expiration: 2037-07-03
Also published as: CN107576394A; FR3053463B1; FR3053463A1; DE102016212088A1

Abstract

The invention relates to an apparatus (100) for defining an angle of incidence (102) for a spectrometer, wherein the apparatus (100) has: a focusing element (104) for focusing light (116) incident on a spectral element disposed behind the device (100) to a focal point (112); a shielding element (108); and a deflecting element (106) for deflecting the focused light rays (116) within the shielding opening (110) of the shielding element (108), wherein the shielding element (108) is arranged in the region of the focal point (112) on an optical axis (114) between the focusing element (104) and the deflecting element (106).

Description

Device for defining an angle of incidence on a spectrometer and method for operating the device

Technical Field

The invention is based on an apparatus or method for defining an angle of incidence for a spectrometer. Computer programs are also the subject of the present invention.

Background

DE 19681285T 1 describes an additional device for infrared microspectroscopy.

Disclosure of Invention

Against this background, the arrangement according to the invention for defining an angle of incidence for a spectrometer, a method for using such an arrangement, and finally a spectrometer are described with the solution presented here. Advantageous modifications and improvements of the device described in the invention are possible by means of the measures listed in the preferred and further embodiments.

A fabry-perot interferometer (FPI) functions as a filter that passes only a narrow band of regions around the resonant wavelength. Micromechanical fabry-perot interferometers are capable of determining the spacing between two mirror elements, the resonance wavelength and the overtones thereof. By changing the pitch, a desired resonance wavelength can be set. In the detector described below, the intensity of the transmission is measured and the spectrum is thus recorded continuously.

In a fabry-perot interferometer, a change in the angle of incidence of the light ray contributes to a shift in the wavelength to be measured. The solution described here prevents light rays from reaching the fabry-perot interferometer filter at different angles of incidence at the same time.

An apparatus for defining an angle of incidence for a spectrometer is presented, wherein the apparatus has: a focusing element for focusing light incident on a spectral element of the spectrometer disposed behind the device to a focal point; a shielding element; and a deflecting element for deflecting the light rays of the spectrometer focused in a shielding opening of the shielding element (for example onto the spectral element), wherein the shielding element is arranged in the region of the focal point on the optical axis between the focusing element and the deflecting element. The deflecting element is also capable of aligning the beam.

The spectral element can be understood as a fabry-perot interferometer. The elements of the spectrum can be arranged in a post-positioned manner in the beam path of the spectrometer of the device. The focus can be a calculated ignition point.

The focusing element and/or the deflecting element can be an optical lens. A straight ray path is obtained through the lens and the optical axis has no offset.

The focusing element and/or the deflecting element can be a mirror. Imaging errors can be avoided by mirrors. The mirror element can be manufactured simply. The mirror can be produced, for example, as a free surface in the injection molding method and the subsequent installation of the reflective layer.

The focusing element and/or the deflecting element can be at least partially a segment of a concave mirror. In particular, the concave mirror can be a parabolic mirror with a defined focal point.

The shielding element can be an aperture plate. The shielding element can have a through-opening for the bundled light. The orifice shield can be simply manufactured.

The shielding element can be at least partially a light conductor. The light guide can be formed, for example, from glass fibers or plastic fibers. The light guide can be bent and, alternatively or additionally, the light is transmitted over a large distance with little attenuation. Thereby, the focusing element and the steering element can be arranged spatially separated.

The optical axis can be oriented transversely to the incident light rays. An optical axis oriented transversely to the incident light rays is understood to mean an orientation of the optical axis which is not oriented parallel, in particular perpendicular, to the incident light rays. By bending in the optical path, a small overall height can be achieved.

Furthermore, a spectrometer with a device according to the aspect described herein is described, wherein the device is preceded by an element of the spectrum of the spectrometer and a light sensor of the spectrometer, and the redirecting element is oriented for redirecting light onto the element of the spectrum.

The elements of the spectrum can for example have two mirror elements whose spacing can be varied in order to influence the resonance wavelength. The light sensor is configured to: the intensity of the light is indicated in the electrical signal.

The spectrometer can comprise at least one further apparatus according to the aspects presented herein. The further device can be arranged adjacent to the device. More light can be directed to the spectrometer by multiple devices than in a single device. The plurality of devices can be arranged around an element of the spectrum.

The spectrometer can have a light source. The light source can be designed to emit light substantially counter to the direction of incidence of the focused element for the light. The light source can be a diode. The light source is capable of emitting light of a particular wavelength. The light sources can be arranged on an axis of symmetry. Thereby errors through parallel axes as in oblique illumination are avoided.

The light source and the light sensor can be arranged on a (e.g. flexible) contact device. The contact device can be bent, in particular around the device. The manufacture can be simplified by the common contact.

Furthermore, a method for defining an angle of incidence to a spectrometer is presented, wherein the method has the following steps:

focusing light incident on the spectrometer to a focal point in the region of the shielding element; and is

An element that diverts light focused in a shutter opening of the shutter element onto the spectrum of the spectrometer.

Drawings

Embodiments of the principles described herein are illustrated in the accompanying drawings and will be explained in greater detail in the following description. The figure is as follows:

FIG. 1 is a schematic illustration of an apparatus for defining an angle of incidence with a lens according to one embodiment;

FIG. 2 is a schematic of an apparatus for defining an angle of incidence with a mirror according to one embodiment;

FIG. 3 is a schematic illustration of an apparatus for defining an angle of incidence with a light guide according to one embodiment;

FIG. 4 is a cross-sectional view of a spectrometer according to one embodiment;

FIG. 5 is a schematic of an arrangement of four devices according to one embodiment;

FIG. 6 is a schematic of a spectrometer according to an embodiment; and

FIG. 7 is a flow diagram of a method for defining an angle of incidence, according to one embodiment.

Detailed Description

In the following description of suitable embodiments of the invention, the same or similar reference numerals are used for elements which are shown in different figures and which function similarly, wherein repeated descriptions of these elements are omitted.

Fig. 1 shows a schematic of an apparatus 100 for defining an angle of incidence 102 with

lenses

104, 106 according to an embodiment. The apparatus 100 can be arranged in front of the elements of the spectrum and define the difference of the angles of incidence 102. The device has a first lens 104 as the focusing element 104 and a second lens 106 as the steering element 106. Between the two lenses 104, 106 a blocking element 108 is arranged. The shielding element 108 is configured as an aperture baffle. The shielding opening 110 of the shielding element 108 is arranged in the region of the focal point 112 of the focused element 104. The shield opening 110 corresponds here to the dimension measured by the inner edge of the recess of the shield element 108. The diverted element 106 has the same focal point 112 as the focused element 104. The deflecting elements 106 are arranged such that the two focal points 112 are located in the same place. Light rays 116 incident parallel to the optical axis 114 of the device are thereby focused by the first lens 104 in the focal point 112 to the ignition point 118, pass unhindered through the blocking opening 110 and are deflected again by the second lens 106 along the optical axis 114.

If the ray 116 strikes the first lens 104 obliquely to the optical axis 114, it is likewise bundled in the ignition point 118. As long as the ignition point is located within the occlusion port 110, the light 116 passes through the occlusion mechanism 108. If the angle of incidence 102 is so large that the ignition point 118 is outside the shadow aperture 110, the shadow mechanism 108 absorbs and/or reflects the light 116 back again.

The basic principle of the lens-aperture baffle-lens solution is shown in fig. 1. In this case, the aperture plate 108 is advantageously located in the vicinity of the plane of the two lens ignition points 112. In this arrangement, the direction of the entrance angle 102 of the first lens 104 is the same as the direction of the output angle of the second lens 106. Light rays 116 within the acceptance angle are not obstructed by the aperture stop 108. If the entrance angle beams 116 of the first lens 104 exceed the acceptance angle, these entrance angle beams are no longer directed towards the second lens 106. This means that at the output of the second lens 106, only the light ray 116 with the largest output acceptance angle is allowed. By matching the focal length from the first lens 104 to the second lens 106, the intensity of the light beam per area unit can be varied.

Fig. 2 shows a schematic of an apparatus 100 for defining an angle of incidence with

mirrors

104, 106 according to an embodiment. The device functions substantially as the device shown in fig. 1. In contrast, the

optical elements

104, 106 are embodied as

concave mirrors

104, 106. Also here, the focusing element 104 focuses the light 116 incident along the optical axis 114 into a focal point 112. The shielding element 108 is arranged with its shielding opening 110 in the focal point 112 or in the focal plane. The deflecting element 106 deflects the light 116 again in the direction of the optical axis 114.

The

mirrors

104, 106 are oriented relative to one another in such a way that the optical axis is oriented between the

mirrors

104, 106 transversely to the optical axis 114 before or after the device 100. The light rays 116 thus have a lateral offset through the device 100.

A comparable structure to the

reflectors

104, 106 is enumerated in fig. 2. This arrangement is less tall and can be produced in a predictable manner from a die cast part with subsequent coating.

Fig. 3 shows a schematic representation of an apparatus 100 for defining an angle of incidence with a light guide 300 according to an embodiment. The device 100 corresponds substantially to the illustration in fig. 2. In contrast, the shielding element 108 is formed here by a light guide 300, which has a cladding or an envelope of the light guide. Here, the diameter of the light-transmitting member of light guide 300 corresponds to shielding opening 110. Light 116 that strikes blocking element 108 outside of light guide 300 does not reach diverted element 106.

By using light guide 300 instead of an aperture plate, it is possible to have the two

reflectors

104, 106 positioned independently of each other.

FIG. 4 shows a cross-sectional view of a spectrometer 400 according to one embodiment. The spectrometer 400 here comprises at least two devices 100, as they are shown in fig. 2. The apparatus 100 confines the difference in the incident angles to an element 402 of the spectrum of the spectrometer 400. The elements 402 of the spectrum are arranged on a light sensor 404. The light 116 arriving through the device 100 is filtered using the spectral elements 402. In this case, only specific wavelengths or specific wavelength ranges pass through the spectral element 402 into the light sensor 404. The light sensor 404 converts the intensity of the touching light 116 into an electrical signal. After detecting the intensity of one wavelength, the elements 402 of the spectrum can be changed to pass other wavelengths. So that multiple measurements can be used to establish a wavelength spectrum of light 116.

In one embodiment, the spectrometer 400 includes a light source 406. The light source 406 is here embodied as a diode which emits light. The light sources 406 are disposed between the devices 100 and oriented such that light they emit impinges on a target object 408 or target in a detection region 410 of the spectrometer 400. The light sensor 404, the spectral element 402, the light source 406 and the detection region 410 are oriented in the symmetry axis 412 of the spectrometer 400.

In an embodiment, the focusing element 104 and the deflecting element 106 are shaped differently than illustrated in fig. 1 to 3. The light rays 116 incident through the shielding opening 110 are thereby deflected by the deflecting element 106 onto the spectral element 402 arranged between the two devices 100. In other words, the device 100 has different incident and exit angles.

In the case of the solution described here, the setting of the angle of incidence region of the beam impinging on the fabry-perot interferometer 402 is carried out by means of the lens/reflector aperture stop arrangement 100. Alternatively, the aperture plate 110 can be replaced by an optical waveguide.

A micromechanical fabry-perot interferometer (FPI) 402 can include two mirror elements arranged on a substrate over a via. The through-opening can be a slot below the two mirrors, which allows light to impinge on the detector. Furthermore, the interferometer can be structured by two substrates with through holes. The light beam is guided perpendicularly through a sandwich construction with two highly reflective mirrors, wherein the region of the respective narrow band around the resonance wavelength and its overtones are transmitted depending on the spacing of the two mirrors. By changing the pitch, a desired resonance wavelength can be set. In the detector 404 described below, the intensity of the transmission is measured and the spectrum is thus continuously recorded. An additional pre-bandpass filter (vorcassette filter) can filter out the desired order of wavelengths, thereby reducing the error through other wavelength devices. Knowledge of the principal incident angle can be used to correct the amount of spectral bias.

In an embodiment not shown, the spectrometer 400 has an off-center illumination device. The reflected light rays 116 at the location of the target 408 are conducted through a mirror or lens to the aperture plate 110 at or near the location of the ignition point and through another mirror or lens to the spectral element 402. The subsequent detector 404 is capable of detecting the sum of the filtered light rays 116.

The combination of the mirror 104 or lens 104, the aperture plate 110 near the ignition point and a further mirror 106 or lens 106, by choosing different focal lengths in order to maximize the intensity at the detector 404, achieves a concentration of the light rays 116.

By virtue of the oblique arrangement of the optical axes of the two

mirrors

104, 106 or

lenses

104, 106, the light 116 can be guided through the interferometer 402 toward the detector 404 in a space-saving manner. The wavelength spectrum error derived therefrom based on the incident angle offset can be compensated by calibration.

A possible configuration is shown in fig. 4, in which there is advantageous axisymmetric illumination. Here, the illumination axis 412 is equivalent to the detector axis 412. In the configuration shown here, the faces of the two

reflectors

104, 106 are rotated in opposition about the ignition point, so that the entry angle of the first reflector 104 differs from the output angle of the second reflector 106. This facilitates an optimal utilization of the installation space.

The structures can be similarly used when such structures are bisected along the optical axis 412. However, in such off-center illumination, the calibration and compensation requirements are high, since the point 406 is not illuminated in different target spacings concentric to the detector axis 412.

Fig. 5 shows a schematic of an apparatus 500 of four apparatuses 100 according to an embodiment. The device 500 here corresponds substantially to the device in fig. 4. In contrast, the deflecting element is covered here by a housing 502. The devices 100 are arranged crosswise and are each rotated by 90 ° toward one another. The housing 502 has four sides, which are configured by the four shielding elements 108. A light source can be arranged on the square cover surface.

A geometric profile 100 is presented in which the difference in the angle of incidence with respect to the surface normal or the optical axis of the resonator mirrors of the spectral element 402 is minimized and at the same time the wavelength intensity of the spectrum reflected by the target 408 on the detector surface 404 is maximized. The average value of the incident angle can be suitably calibrated.

The aperture plate 108 reflects or absorbs light rays outside the interior structural space, so that only a small number of erroneously transmitted light rays can reach the interferometer-detector combination at different angles of incidence.

In fig. 5, an advantageous configuration 500 is shown, in which four reflectors 104-aperture baffle 108-reflector combination 100 are arranged symmetrically and a square base surface is well utilized. The structure 500 can also have more than four segments. The illumination can be centered on the central support 502, so that an axisymmetric configuration is possible.

Concentric radial light guidance through the surrounding pinhole aperture is possible if the number of reflector-aperture baffle-reflector combinations 100 around the optical axis is chosen to be large.

FIG. 6 shows a schematic diagram of a spectrometer 400 according to an embodiment. The spectrometer 400 is shown in cross-sectional and top views. The spectrometer 400 substantially corresponds to the illustration in fig. 4. Additionally, a contact device 600 is shown here for electrically contacting the spectral element 402, the light sensor 404 and the light source 406. The contact device 600 has a flexible circuit board 602 with a stiffening element 604. The spectral element 402, the light sensor 404 and the device 500 are arranged on the stiffening element 604. The device 500 substantially corresponds to the device in fig. 5. Additionally, the device 100 is herein incorporated as one component. The light source 406 is arranged on a finger 606 of the flexible circuit board 602, which finger is bent at 180 ° and is arranged on the cover side of the device 500. Here, the light source 406 is arranged on the same side of the circuit board 602 as the stiffening element 604. The light source 406 emits its light through the notch of the circuit board 602. The finger 606 runs here between the two devices 100 via the tab.

In other words, fig. 6 shows a structural element 400 configured as a compact spectrometer 400, wherein the structural element 400 comprises a light source 406, a light guide 100 with an element 402 defining the difference in incident angle to the spectrum, and a light sensor 404.

Here, the light guide 100 is formed of a plurality of different segments in order to maximize the intensity at the detector 404. The light guide 100 is formed by reflectors or lens geometries, which can be formed from a continuous surface or constructed as a fresnel lens.

In one exemplary embodiment, spectral element 402 has a micromechanical fabry-perot interferometer component, at least one base body and two mirror elements stacked on top of one another, which are spaced apart from one another by a gap.

In fig. 6 a possible irradiation contact 600 with a flexible lead (Flexlead) 602 is shown. Additional supports between the reflectors can improve the stability of the structure 500 and ensure a suitable cooling of the irradiation section 406.

Fig. 7 shows a flow diagram of a method 700 for defining an angle of incidence according to an embodiment. The method can also be understood as a method 700 for operating the aforementioned variants of the device 100. The method has a step 701 of focusing and a step 702 of steering. In a focusing step 701, light incident on the spectrometer is focused to a focal point in the region of the blocking element. In a diverting step 702, the light focused in the shielding port of the shielding element is diverted onto an element of the spectrum of the spectrometer.

This is to be interpreted as if an embodiment includes an "and/or" association between a first feature and a second feature: that is, this embodiment has the first feature as well as the second feature according to one embodiment, and either only the first feature or only the second feature according to another embodiment.

Claims

1. An apparatus (100) for defining an angle of incidence (102) for a spectrometer (400), wherein the apparatus (100) has: a focusing element (104) for focusing light rays (116) incident on a spectral element (402) disposed behind the device (100) to a focal point (112); a shielding element (108); and a deflecting element (106) for deflecting the focused light rays (116) within a shielding opening (110) of the shielding element (108), wherein the shielding element (108) is arranged between the focusing element (104) and the deflecting element (106) on an optical axis (114) in the region of the focal point (112), wherein the shielding element (108) is at least partially a light conductor (300).

2. The device (100) according to claim 1, in which the focusing element (104) and/or the deflecting element (106) is an optical lens.

3. The device (100) according to any one of the preceding claims, in which the focusing element (104) and/or the steering element (106) is a mirror.

4. The device (100) according to claim 3, in which the focusing element (104) and/or the deflecting element (106) is at least partially a segment of a concave mirror.

5. Device (100) according to any one of the preceding claims, in which the shutter element (108) is an aperture baffle.

6. The device (100) according to any one of the preceding claims, in which the optical axis (114) is oriented transversely to the incident light ray (116).

7. A spectrometer (400) having a device (100) according to any of the preceding claims, wherein the device (100) is preceded by an element (402) of the spectrum of the spectrometer (400) and a light sensor (404) of the spectrometer (400), and the turning element (106) is oriented for turning light rays onto the element (402) of the spectrum.

8. The spectrometer (400) according to claim 7, having at least one further device (100) according to any of claims 1 to 6, wherein the further device (100) is arranged adjacent to the device (100).

9. The spectrometer (400) according to any of the preceding claims, having a light source (406), in particular wherein the light source (406) is configured for: the light is emitted substantially against the direction of incidence of the focused element (104) for the light.

10. The spectrometer (400) according to claim 9, in which the light source (406) and the light sensor (404) are arranged on a contact device (600), in particular wherein the contact device (600) is bent around the apparatus (100).

11. A method (700) for operating an apparatus (100) for defining an angle of incidence (102) for a spectrometer (400) according to any of the preceding claims, wherein the method has the steps of:

focusing (701) light rays (116) incident on an element (402) of the spectrum of the spectrometer (400) onto a focal point (112) in the region of the shielding element (108); and is

-diverting (702) the light rays (116) focused in the shielding opening (110) of the shielding element (108) onto an element (402) of the spectrum of the spectrometer (400).