Spectrometer Device and Method for Producing a Spectrometer Device

Abstract

A spectrometer device includes an optical interference filter which is designed to filter specific wavelength ranges of an incident light beam on passage through the optical interference filter. The spectrometer device also includes a detector device which is designed to detect the filtered light beam. Further, the spectrometer device includes a focusing device with a reflective surface. The focusing device is designed to focus the filtered light beam onto the detector device by reflection on the surface.

Claims

1. A spectrometer device, comprising: an optical interference filter which is configured to filter particular wavelength ranges of an incident light beam when it passes through the optical interference filter; a detector instrument which is configured to detect the filtered light beam; and a focusing instrument having a reflective surface, the focusing instrument; being configured to focus the filtered light beam onto the detector instrument by reflection on the surface.

2. The spectrometer device as claimed in claim 1, wherein the detector instrument is integrated into the interference filter, or arranged directly or indirectly on the interference filter, on a light exit side of the interference filter.

3. The spectrometer device as claimed in claim 1, wherein the detector instrument overlaps at least partially with an axis extending through a center of the optical interference filter.

4. The spectrometer device as claimed in claim 1, having further comprising a carrier instrument wherein: the optical interference filter, the detector instrument and the focusing instrument are arranged directly or indirectly on the carrier instrument.

5. The spectrometer device as claimed in claim 4, wherein the detector instrument is arranged next to the interference filter on the carrier instrument on a light exit side of the optical interference filter.

6. The spectrometer device as claimed in claim 4, wherein the carrier instrument comprises at least one spacer element, which connects the focusing instrument to the optical interference filter and spaces them apart from one another, the at least one spacer element at least locally having an absorbent coating.

7. The spectrometer device as claimed in claim 4, wherein a surface section of the detector instrument and/or a surface section, next to the detector instrument, of the interference filter and/or of the carrier instrument at least locally has an absorbent coating.

8. The spectrometer device as claimed in claim 1, wherein the detector instrument comprises a ring detector, segmented detector elements and/or detector elements arranged so as to form an array.

9. The spectrometer device as claimed in claim 1, wherein the detector instrument comprises at least two stacked detector elements, which are sensitive for different wavelength ranges.

10. The spectrometer device as claimed in claim 1, wherein the optical interference filter is configured as a Fabry-Perot interference filter.

11. A method for producing a spectrometer device, with (i) an optical interference filter, which is configured to filter particular wavelength ranges of an incident light beam when it passes through the optical interference filter, (ii) a detector instrument, which is configured to detect the filtered light beam, and (iii) a focusing instrument having a reflective surface, comprising: arranging the focusing instrument, the detector instrument and the optical interference filter with respect to one another in such a way that the focusing instrument focuses the filtered light beam onto the detector instrument.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 shows a schematic cross-sectional view of a spectrometer device according to a first embodiment of the invention;

[0026] FIG. 2 shows a schematic cross-sectional view of a spectrometer device according to a second embodiment of the invention;

[0027] FIG. 3 shows a schematic cross-sectional view of a spectrometer device according to a third embodiment of the invention;

[0028] FIG. 4 shows a schematic cross-sectional view of a spectrometer device according to a fourth embodiment of the invention; and

[0029] FIG. 5 shows a flowchart to explain a method for producing a spectrometer device according to one embodiment of the invention.

[0030] In all the figures, elements and devices which are the same or functionally equivalent are provided with the same references. The numbering of method steps is used for clarity and is not in general intended to imply a particular chronological order. In particular, a plurality of method steps may also be carried out simultaneously.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0031] FIG. 1 shows a schematic cross-sectional view of a spectrometer device 1a, which has a carrier device 6a that in turn comprises a substrate 61, into which an optical interference filter 2 or spectral element is integrated. The carrier device 6a furthermore comprises holding elements 62, which hold a focusing instrument 4a.

[0032] The optical interference filter 2 is a preferably micromechanically produced Fabry-Perot interference filter. The optical interference filter comprises two mirrors that are spaced apart relative to one another and can be actuated relative to one another. Depending on the angle of incidence of the light beams L on the optical interference filter 2, light beams L are transmitted with a slightly different central wavelength. The central wavelength furthermore depends on the distance of the two mirrors from one another. Preferably, the optical interference filter 2a has an encapsulation on one side or particularly preferably both sides. According to further embodiments, however, optical interference filters 2 with a different design and functionality are also possible.

[0033] On a light exit side of the optical interference filter 2, a detector instrument 3 is arranged in a central position.

[0034] The detector instrument 3 is connected directly to the optical interference filter 2, for instance by an adhesive connection or a bond connection. The detector instrument 3 may, for example, be applied on a cap of the optical interference filter 2. The detector instrument 3 may comprise at least one photodiode as a detector element, which, as a function of the intensity of the incident light beams L, generates a photocurrent that can be measured and further evaluated. The spectrometer device 1a can deliver a measurement signal as a function of the photocurrent. According to further embodiments, the detector instrument 3 may comprise a multiplicity of detector elements, which are preferably sensitive at different wavelengths. It is furthermore possible to provide a ring detector which is arranged symmetrically around the middle of the input aperture of the optical interference filter 2, i.e. around an axis through the center of the optical interference filter 2. The detector instrument 3 may furthermore comprise at least one segmented detector element. By the use of ring detectors or segmented detector elements, a plurality of angle intervals and/or different wavelength ranges may be detected. In order to acquire different wavelength ranges, the detector instrument 3 may also comprise stacked detectors, i.e. dual detectors. The material of the detector elements of the detector instrument 3 may for example comprise silicon Si, indium gallium arsenide InGaAs, germanium Ge or lead selenide PbSe. Furthermore possible are detector materials based on quantum dots or dual detectors with InGaAs+Si material combinations. Besides individual detectors, the detector instrument 3 may also comprise array detectors. Furthermore, the detector instrument 3 may comprise additional imaging optics.

[0035] The focusing instrument 4a is configured as a parabolic mirror with a focal length f. The detector instrument is arranged in the middle of the input aperture of the optical interference filter 2, i.e. at the focal point of the symmetrically configured focusing instrument 4a, i.e. the focusing instrument 4a focuses light beams L that pass through the optical interference filter 2, and whose angle of incidence does not exceed a predetermined threshold value, onto the detector instrument 3. Light rays L with a higher angle of incidence are deflected into a region next to the detector instrument 3. A coating of an absorbent material, which absorbs the light beams L, is preferably arranged in this region next to the detector instrument 3 on the rear side, or light exit side, of the optical interference filter 2. The focusing instrument 4a may have a coating of a reflective material, in particular silver, gold or aluminum. At least one protective layer may additionally be provided. In particular, the focusing instrument 4a may be configured as a coated injection-molded part, or one on which vapor deposition has been carried out. According to further embodiments, the focusing instrument 4a may comprise lathed or milled parts, in particular made of aluminum. Instead of or in addition to reflective focusing mirrors, the focusing instrument 4a may also comprise further reflective optical components such as reflective, so-called metasurfaces.

[0036] The detectable angle of incidence interval is restricted and the resolution of the spectrometer device 1a is therefore adjusted, or optimized, as a function of the usable aperture a of the optical interference filter 2, or the usable diameter of the focusing instrument 4a, the focal length f of the focusing instrument and the size of the sensitive region of the detector instrument 3.

[0037] FIG. 2 shows a spectrometer device 1b which represents a variant of an above-described spectrometer device 1a and differs in the configuration of the carrier instrument 6b. Accordingly, the carrier instrument 6b comprises spacer elements 7, which connect the focusing instrument 4a to the optical interference filter 2 and space these elements apart from one another. The carrier instrument 6b may, in particular, be cylindrically configured. The spacer elements 7 preferably have an absorbent coating, which absorbs possible scattered light, on their inner side. The spacer elements 7 may be an additional layer, or a layer stack, or an element, for instance a wafer, connected by means of an adhesive connection or a bond connection. According to further embodiments, the focusing element 4a may be connected directly to the optical interference filter 2, for instance by means of an adhesive connection or a bond connection.

[0038] FIG. 3 shows a further spectrometer device 1c, which represents a variant of the above-described spectrometer devices 1a, 1b. The carrier instrument 6c may correspond to one of the carrier instruments 6a, 6b described above. In contrast to the spectrometer devices 1a, 1b depicted above, the focusing instrument 4c is configured asymmetrically, for example as a so-called off-axis reflector, i.e. the focal point of the focusing instrument 4c lies not at the center of the optical interference filter 2 but in a region outside the optical interference filter 2. Correspondingly, the detector instrument 3 is arranged on the carrier instrument 6c outside the optical interference filter 2 on a side facing toward the focusing instrument 4c, the focusing instrument 4c focusing the light beam L onto the detector instrument 3 after it passes through the optical interference filter 2. By the detector instrument 3 being arranged next to the optical interference filter 2, shadowing by the detector instrument 3 and by supply leads of the detector instrument 3 may be avoided, which may nevertheless be advantageous particularly in the case of relatively small input apertures despite the inferior ratio of input aperture a to focal length f due to the inferior light efficiency or the larger overall height as well as the increased reflection losses during the coupling of light into the detector instrument 3.

[0039] FIG. 4 shows a cross-sectional view of a further spectrometer device 1d, which is a variant of the spectrometer device 1c shown in FIG. 3. According to this embodiment, the carrier element 6d comprises a housing 63 of the optical interference filter 2 as well as a carrier plate 64, the detector instrument 3 being arranged on a side of the carrier plate 64 facing toward the symmetrical focusing instrument 4c.

[0040] A flowchart of a method for producing a spectrometer device, in particular one of the spectrometer devices 1a, 1b, 1c, 1d described above, is illustrated in FIG. 5.

[0041] In a first step S1, an optical interference filter 2 is provided, in which case the optical interference filter 2 may in particular be an interference filter for a Fabry-Perot interferometer. The optical interference filter 2 is configured in such a way that particular wavelength ranges of an incident light beam L are filtered when it passes through the optical interference filter 2.

[0042] In a further method step S2, a detector instrument 3, which is configured to detect the filtered light beam L, is provided. In particular, the optical interference filter 2 and the detector instrument 3 may be arranged on a common carrier instrument 6. The detector instrument 3 may also be arranged directly on the optical interference filter 2, optionally by means of additional intermediate layers.

[0043] In a method step S3, a focusing instrument 4a, 4c, which has a reflective surface 5, is provided. The focusing instrument 4a, 4c may be configured symmetrically or asymmetrically, the arrangement of the focusing instrument 4a, 4c, the detector instrument 3 and the optical interference filter 2 being carried out in such a way that a light beam L filtered by the optical interference filter 2 is focused onto the detector instrument 3 by means of the focusing instrument 4a, 4c.

[0044] The method steps S1, S2, S3 may be carried out in any desired order, and in particular even simultaneously.