Optical mounts and spectrometers equipped with optical mounts

Abstract

An optical mount comprising an optical selector having a first optical holder for mounting a reflective first optical component and a second optical holder for a plurality of second optical components. The second holder may be mounted to rotate about a selection axis BB, and at different angular positions about the selection axis BB, the second holder positions one of the different selected second optical components in the optical path such that light on the optical input path is directed to the optical output path via the first optical component and the selected second optical component. The mount comprises a mechanism for rotating the selected second optical component when it is in the optical path and moving a mirror through the first optical holder in conjunction with the rotation of the selected second optical component, so that light guided along the input path is directed to the optical output path at different angular positions of the selected second optical component relative to the optical output path.

Description

Technical Field

[0001] The present invention relates to an optical mount and a spectrometer including the optical mount. Specifically, but not limited thereto, the present invention relates to an optical mount arranged for mounting first and second optical components to define an optical path, the optical mount including a mechanism for moving the first optical component in conjunction with rotation of the second optical component, such that light guided along an input optical path is directed along the same output optical path at different angular positions of the second optical component.

Background Art

[0002] The Raman effect is a phenomenon in which a sample scatters incident light of a specific frequency and generates a frequency spectrum having characteristic peaks caused by the interaction between the incident light and the molecules constituting the sample. Since different molecular species have different characteristic Raman peaks, the effect can be used to analyze the existing molecular species.

[0003] [[ID=1^6]]A known Raman spectroscopy system is described in WO2008 / 045497A1. Referring to FIG. 1 of WO2008 / 045497A1, light guided along an input path from a laser light source 10 is reflected by an input mirror 14 and a notch or edge filter 16 (hereinafter referred to as a "Rayleigh filter") functioning as a dichroic beam splitter. Thereby, the light is directed along an output optical path toward a microscope 〖8〗, where it is deflected by a mirror 20 and focused on a sample 24 through an objective lens 22. Raman scattering occurs in the sample and generates Raman-shifted light having a different frequency from the incident laser beam. The Raman-shifted light is collected by the objective lens 22 and returned along the optical path to the Rayleigh filter 16 via the mirror 20.

[0004] The Rayleigh filter 16 reflects light of the laser wavelength while transmitting light of the Raman-shifted wavenumber, blocking laser rays of much higher intensity. Further blocking of the laser rays occurs in a second identical filter 26. The Raman-shifted light then passes through a Raman analyzer 28, which may include a diffraction grating or a filter that accepts specific target Raman rays. The resulting light is then transmitted to a detector 30, which may include, for example, a charge-coupled device (CCD) on which the Raman spectrum can be dispersed by a diffraction grating. Alternatively, the filter may transmit a two-dimensional image of the sample to the CCD, taking into account the selected Raman wavenumber.

[0005] The Rayleigh filter 16 needs to be positioned at a certain angle to the optical path in order to direct light from the light source 10 toward the sample 24. However, this angle should be a low angle of incidence in order to provide a sharp cutoff between blocking the laser beam and accepting Raman scattered light at wavenumbers close to the laser beam. WO2008 / 045497A1 discloses angles between 7.5° and 13°.

[0006] Figure 1 of the attached drawings schematically shows an optical mount 100 for the input mirror 114 and Rayleigh filter 116 used in HORIBA's LabRAM Raman spectrometer. The optical mount 100 has a mechanism arranged to mechanically adjust the position of the input mirror 114 in conjunction with the angle of the Rayleigh filter 116, so that at different angular positions of the Rayleigh filter 116, the light guided along the laser beam input path 113 is directed along the same laser output beam path 115. The Raman backscattered light is returned along the laser beam output path 115, passes through the Rayleigh filter 116, and is directed along path 117 toward the analyzer (not shown). Changing the angle of the Rayleigh filter 116 changes the wavenumber filtered by the Rayleigh filter 116. Depending on the application, it may be useful to adjust (tune) the angle of the Rayleigh filter 116 to filter wavenumbers further away from the laser wavelength to reduce the effect of Rayleigh scattered light on the detected spectrum, or to transmit wavenumbers closer to the laser beam wavelength to detect Raman scattered light of these wavenumbers.

[0007] The Rayleigh filter 116 is positioned to rotate around a pivot point 107 fixed to the input and output paths 113 and 115. The input mirror 114 is positioned to rotate around a pivot point 109 movable along a linear slider 121. A motor (not shown) drives the linear motion of the input mirror 114 along the slider 121. The linear motion of the input mirror 114 along the slider 121 causes the input mirror 114 to rotate around the pivot point 109 and the Rayleigh filter 116 around the pivot point 107, and despite the changing angle of the Rayleigh filter 116 relative to the output path 115, the laser beam guided along the input path 113 is directed towards the output path 115 by a mechanism 111.

[0008] One form of the spectrometer includes a linear selector 131 for changing the Rayleigh filter 116 in the optical path to different Rayleigh filters 116a, 116b. The linear selector 131 includes a lead screw 132 driven by a motor 133 to move the selector to different positions where the different Rayleigh filters 116, 116a, and 116b are located in the optical path of the laser beam. The linear selector 131 rotates around a pivot point 107 and forms a large sweep area which should not contain other components of the spectrometer. Adding an additional Rayleigh filter 116 requires a longer linear selector 131 and increases the space required for the device.

[0009] Furthermore, it is difficult to manufacture a mirror suitable for use as an input mirror 114 that has high reflectivity over a wide range of wavelengths. [Overview of the project]

[0010] According to a first aspect of the present invention, an optical mount is provided comprising: a first optical holder for mounting a reflective first optical component; an optical selector for mounting a plurality of second optical components, the optical selector being arranged to selectively position one of different second optical components within an optical path such that light on an optical input path is directed through a first optical component and a selected second optical component to an optical output path; and a mechanism for rotating the selected second optical component while it is in the optical path, and moving the first optical holder in conjunction with the rotation of the selected second optical component, so that light guided along the input path is directed along the optical output path at different angular positions of the selected second optical component with respect to the optical output path.

[0011] The optical selector may include a second optical holder for a plurality of second optical components. The second holder may be mounted to rotate about a selection axis, and at different angular positions about the selection axis, the second holder positions one of different selected second optical components in the optical path. The optical holder may have a wheel, the selection axis being the wheel axis, and the second optical components are mounted about the wheel axis. The second optical holder may be arranged to mount four or more second optical components, more preferably five or more, even more preferably six or more, even more preferably seven or more, and most preferably eight second optical components. The use of a second optical holder that rotates to selectively position second optical components in the optical path may allow for closer packing of such a number of second optical components compared to the linear optical selector of the prior art.

[0012] A second optical holder may be mounted to rotate the selected second optical component about an incident angle axis perpendicular to the incident plane of the selected second optical component. The incident angle axis may intersect the selected second optical component, preferably the incident plane of the selected second optical component. The incident planes of the selected second optical component, preferably the planes of each incident plane of the second optical component, may be parallel to the incident angle axis. The incident angle axis may be perpendicular to the wheel axis. The incident angle axis may intersect the wheel axis. The rotation of the second optical holder about the incident angle axis adjusts the incident angle of light (such as a laser beam or backscattered light) on the selected second optical component.

[0013] The mount may have a base, and the optical selector may have a support on which a second optical holder is mounted so that the second optical holder can rotate on the support, and the support is mounted on the base so as to rotate relative to the base.

[0014] The optical mount may include a motor for rotating the second optical holder. The wheel may be mounted to the motor such that the wheel axis is common to the motor axis, i.e., the wheel is directly driven by the motor. In this way, no additional bearings are required for the wheel.

[0015] The mount may include a second optical holder encoder for measuring the rotational position of the second optical holder. The second optical holder encoder may be an absolute encoder.

[0016] The mount may include a second optical component encoder for measuring the rotational position of a selected second optical component relative to the optical output path. The second optical component encoder may be an absolute encoder. The second optical component encoder may also be a linear encoder. The use of a linear encoder for measuring the rotational position of a selected second optical component relative to the optical output path can provide sufficient accuracy because the change in rotation angle is small, and linear encoders are less expensive and easier to install than rotary encoders.

[0017] The optical selector may include a detent that mechanically prevents the rotation of the second optical holder at set positions, each set positioning one of the second optical components within the optical path. In this way, when the second optical holder is rotated to the desired position, the motor can be turned off, reducing the heat generated within the device that may affect the positioning of the optical components. The detent may include a notch in the wheel and a catch that is biased toward the wheel so that the catch engages with the corresponding notch when the notch aligns with the catch. Rotation of the wheel by the motor may push the catch out of the notch.

[0018] Each second optical component can be kinematically mounted to the second optical holder. The kinematic mounting of each second optical component can define the position of the second optical component with six degrees of freedom.

[0019] The optical input path may cross the optical output path. The first optical holder may be positioned to mount the first optical component such that the angle of incidence of the optical input path to the first optical component is less than 45°. The first optical holder may be positioned to mount the first optical holder such that the angle of incidence is less than 45° for all positions of the first optical holder when mounted in the first optical holder. The first optical component may be a mirror, such as a dielectric mirror. Dielectric mirrors that provide high reflectivity over a wide range of wavelengths for an angle of incidence of less than 45° to the optical input path of the dielectric mirror are readily available.

[0020] Multiple second optical components may comprise two or more filters. Each filter may transmit wavelengths in different ranges (for the same angle of incidence of incident light). Each filter may be a notch filter.

[0021] According to a second aspect of the present invention, a spectrometer is provided that includes an optical mount according to the first aspect of the present invention. The spectrometer may include a laser positioned to direct laser light along an optical input path and an analyzer positioned to receive light transmitted by a selected second optical component. The spectrometer may be a Raman spectrometer.

[0022] According to a third aspect of the present invention, an optical selector is provided comprising a motor having a motor shaft and a wheel attached to the motor shaft, the wheel having mounting portions for attaching a plurality of optical components at circumferential positions centered on the motor shaft axis.

[0023] In this way, the wheel is mounted on a motor shaft that has its own bearings, i.e., it is a direct drive mechanism, and therefore does not require separate bearings for the wheel. This reduces the number and complexity of components in the optical selector.

[0024] The optical selector may comprise a base, and the wheel may be attached to the base so as to rotate about the incident angle axis. The incident angle axis intersects the selected optical component of the plurality of optical components selected by the optical selector so as to be positioned on the optical path of light, preferably the incident surface of the selected optical component. The plane of the selected optical component, preferably each optical component, may be parallel to the incident angle axis. The incident angle axis may be perpendicular to the motor shaft axis. The incident angle axis may intersect the motor shaft axis. The rotation of the wheel about the incident angle axis adjusts the incident angle of light (such as a laser beam or backscattered light) on the selected second optical component.

[0025] The optical selector may comprise a support to which the wheel is attached so that the wheel can rotate on the support, and the support is attached to the base for rotation relative to the base.

[0026] According to a fourth aspect of the present invention, there is provided an optical selector comprising a wheel mounted for rotation, the wheel comprising a mounting portion for mounting a plurality of optical components at circumferential positions about a rotation axis, and a detent for mechanically blocking the rotation of the wheel at a set position of the wheel, each set position positioning a different one of the optical components within the optical path.

[0027] In this way, when the wheel is rotated to the required position, the motor can be turned off, reducing the heat generated within the device that could potentially affect the positioning of the optical components. The detent may comprise a notch in the wheel and a catch biased towards the wheel so as to engage the corresponding notch when the notch aligns with the catch. The rotation of the wheel by the motor can push the catch out of the notch.

[0028] According to a fifth aspect of the present invention, there is provided a spectrometer comprising an optical selector according to the third aspect, and / or the fourth aspect of the present invention.

Brief Description of the Drawings

[0029] [Figure 1] Figure 1 is a schematic diagram of a conventional optical mount. [Figure 2] Figure 2 is a schematic diagram of a spectrometer according to an embodiment of the present invention. [Figure 3] Figure 3 is a perspective view from one side of an optical mount according to an embodiment of the present invention. [Figure 4] Figure 4 is a perspective view from the opposite side of the optical mount. [Figure 5] Figure 5 is a plan view of the optical mount.

BEST MODE FOR CARRYING OUT THE INVENTION

[0030] Referring to Figure 2, light such as a laser beam from a laser light source 210 is directed towards an optical device along an optical input path 213. The optical device includes an optical mount 200 to which a mirror 214 and a Rayleigh filter 216 are attached. In this embodiment, the Rayleigh filter 216 is a notch or edge filter that functions as a dichroic beam splitter. The mirror 214 and the Rayleigh filter 216 reflect a laser beam directed along the optical input path 213 to an optical output path 215. The laser beam directed along the optical output path 215 enters a microscope 218, and the laser beam is deflected by a mirror 220, passes through an objective lens 222, and is focused on a sample 224. Raman scattering occurs in the sample, generating Raman-shifted light having a frequency different from that of the incident laser beam. The Raman-shifted light is collected by the objective lens 222 and returned to the Rayleigh filter 216 along the optical path 215 via the mirror 220.

[0031] The Rayleigh filter 216 reflects light of the laser wavelength while transmitting light of the Raman-shifted wavenumber, blocking laser beams of much higher intensity. The Raman-shifted light then passes through a Raman analyzer 228, which may include a diffraction grating or a filter that accepts specific target Raman rays. The resulting light is then transmitted to a detector 230, which may include, for example, a charge-coupled device (CCD) on which the Raman spectrum can be dispersed by a diffraction grating. Alternatively, the filter may transmit a two-dimensional image of the sample to the CCD, taking into account the selected Raman wavenumber.

[0032] The Rayleigh filter 216 needs to be positioned at a certain angle to the optical path in order to direct the laser beam from the light source 210 toward the sample 224. By adjusting the angle of the Rayleigh filter 216 with respect to the output optical path 215, the wavenumber transmitted or reflected by the Rayleigh filter 216 can be adjusted. However, if the angle of the Rayleigh filter 216 is adjusted alone, for some angles the laser beam will not be directed along the output optical path 215. Therefore, the mount 200 is positioned to move the mirror 214 in conjunction with the rotation of the Rayleigh filter 216 so that the laser beam guided along the optical input path 213 is directed along the optical output path 215 at different angular positions of the Rayleigh filter 216.

[0033] Referring to Figures 3 to 5, the optical mount 200 comprises a first optical holder 201 for mounting the mirror 214 and an optical selector 202 for mounting a plurality of second optical components 216, 216a, 216b, including at least two Rayleigh filters. The optical selector 200 is positioned to selectively position one of the second optical components 216, 216a, 216b within the optical path 203 so that the laser beam on the optical input path 213 is guided through the mirror 214 and the selected second optical component 216 to the optical output path 215.

[0034] The mount includes a mechanism for rotating a selected second optical component 216 when it is in the optical path, and for moving a mirror 214 via a first optical holder 201 in conjunction with the rotation of the selected second optical component 216, so that light guided along the input path 213 is directed towards the optical output path 215 at different angular positions of the selected second optical component 216 relative to the optical output path. The first optical holder 201 is connected to a slider 221 via a pin 209 and is rotatable about axis AA. The slider 221 is guided for linear motion along a guide 223 on a base 205. The movement of the slider 221 along the guide 223 moves the first optical holder 214 and, therefore, moves the axis of rotation AA in a linear direction. The movement of the slider 221 is driven by a motor 208 via a transmission mechanism, in this embodiment a rack 217 and a pinion 219. The spring 211 between the slider 221 and the guide 223 absorbs the backlash of the transmission mechanism.

[0035] The optical selector 202, in this embodiment, comprises a second optical holder in the form of a wheel 229 mounted to rotate on a support 231. A plurality of second optical components 216, 216a, 216b are mounted on the wheel 229, and rotation of the wheel 229 to different angular positions about the selection axis BB selectively positions one of the second optical components 216, 216, 216b within the optical path 203. The wheel 229 is mounted on the shaft of the motor 232 so that the rotation of the wheel 229 is directly driven by the motor 232. In one embodiment, an additional filter may be mounted on the rear of the wheel 229 so that light passing through the selected filter also passes through an additional filter. Such an additional filter may be used to further refine the filtered light that is led to the analyzer. There may be corresponding additional optical components for each of two or more of the second optical components 216, 216, 216b that allow light to pass through there.

[0036] The optical selector 202 includes a detent mechanism that holds the wheel 229 in a position that positions a selected second optical component within the optical path without requiring power to be supplied to the motor 232. The detent mechanism comprises a notch 233 on the wheel 229 and a catch 234 biased toward the wheel 229 by a spring, in this embodiment a flat spring 235, and when the catch 234 is aligned with one of the notches, the catch 234 is received by the notch 233 to prevent rotation of the wheel 229 around the motor axis BB. The catch 234 is located on the side of the wheel 229 rather than on the top of the wheel 229 opposite the base 205. (The side of the wheel is the left and right position of the wheel axis, and the part of the wheel closest to the base is considered the bottom.) This may be beneficial in reducing the height of the optical selector 202 from the base 205.

[0037] The wheel 229 is mounted on the support 231 via the motor 232. The support 231 is mounted on the base 205 for rotation around the incident angle axis CC. The incident angle axis is perpendicular to and intersects with the incident plane of the selected second optical component 216. Rotation of the support 231 around the incident angle axis CC adjusts the incident angle of light (laser beam and backscattered light) on the selected second optical component 216. In this way, the wavenumber reflected and transmitted by the selected second optical component 216 can be changed.

[0038] A second optical holder absolute encoder (not shown) is positioned to measure the rotational position of the support 231, and therefore the selected second optical component 216, about the incident angle axis CC. In this embodiment, the second optical component encoder is a linear encoder. The use of a linear encoder to measure the rotational position of the support 231 about axis CC can provide sufficient accuracy because the rotational range about axis CC is less than 10° or less than 5°, for example.

[0039] The wheel 229 is positioned to mount eight second optical components (although the drawing shows only three 216, 216a, and 216b). Each second optical component 216, 216a, and 216b is mounted on a plate 236. In this embodiment, the plate 236 is triangular so that it fits circumferentially around axis BB. Each plate is kinematically mounted to the wheel 229. To achieve this, three mounting structures on the plate 236, in this embodiment, three machined slots in the plate 236 cooperate with a set of three corresponding mounting structures on the wheel 229, in this embodiment, three hemispheres. Fastening members, in this embodiment, a pair of bolts, compress springs to bias the mounting structures to engage. Each hemisphere may be provided by threaded ends protruding from holes in the wheel 229. The adjustment of the screws adjusts the position of the hemispheres, and therefore the position of the incident planes of the corresponding second optical components 216, 216a, and 216b.

[0040] The support 231 further comprises rollers 225, 226, and 227. Rigidly connected to the first optical holder 201 is a guide rod 206 extending between the rollers 225, 226, and 227. The rollers 225, 226, and 227 are biased against the guide rod 206 by a plane spring 237. Movement of the slider 221 moves the axis of rotation AA in a linear direction, displacing the first optical holder 201. The displacement of the first optical holder 221 moves the guide rod 206 between the rollers 225, 226, and 227. However, since the displacement caused by the movement of the slider 221 is not parallel to the guide rod 206, the optical holder 201 must also rotate around axis AA to accommodate the displacement, thereby rotating the guide rod 206. The rollers 225, 226, and 227 follow this rotation of the guide rod 206, causing the support 231 to rotate about the incident angle axis CC. Thus, the movement of the slider 221 displaces and rotates the mirror 214, and rotates the selected second optical component 216. The mechanism is geometrically arranged so that the position of the first mirror 214 is adjusted so that the laser beam is directed along the output optical path 215 at different angular positions of the selected second optical component 216. In this embodiment, the slider 221 moves in a linear direction that is 45° with respect to the input optical path 213 and 45° with respect to the output optical path 215. The normal to the surface of the selected second optical component 216 intersects axis AA. The guide rod 206 extends along a line parallel to the normal to the surface of the selected second optical component 216. The sum of the angle of the surface normal of mirror 214 with respect to the input light path 213 and the angle of the surface normal of the selected second optical component 216 with respect to the output light path 215 is equal to 45°. Mirror 214 can be moved to a position where the angle of the surface normal of mirror 214 with respect to the input light beam 214 is less than 45°.

[0041] In such an arrangement, the optical input path 213 intersects with the optical output path 215. Preferably, the first optical mirror is a dielectric mirror that provides high reflectivity over a wide range of wavelengths for an incident angle of the optical input path to the dielectric mirror less than 45°.

[0042] One of the second optical components could be a standard mirror that can be used for calibration.

[0043] In use, the user selects Rayleigh filters 216, 216a, and 216b for use in a specific application. This may be based on the wavelength of the laser light used to excite the sample, the sample being analyzed, and / or the target Raman wavenumber. The user inputs the required Rayleigh filters to the spectrometer's controller, for example, via a user interface (not shown), and the controller controls motor 232 to position the required Rayleigh filters within the optical path 203. Once the required Rayleigh filters 216, 216a, and 216b are positioned within the optical path 203, power to motor 232 is turned off. The angles of the Rayleigh filters 216, 216a, and 216b relative to the optical output path 215 are set to angles preset by the user. For this purpose, the user interface may allow the user to input the preset angles to the controller. Motor 208 is operated by the controller to set the angle of the selected Rayleigh filter 216 based on the preset angles. Subsequently, the user can change the preset angle for different applications and / or different sampling requirements. For example, samples with strong Raman scattering can obtain a closer edge position due to the trade-off of Rayleigh blocking, providing access to additional low-wavenumber chemical information.

[0044] Optionally, the tuning process may be performed using a motor 208 to adjust the angle of a second optical component 216 selected to filter the required wavenumbers based on noise measurements. Again, this may be performed by the user providing appropriate inputs to the spectrometer's controller, or the device such as the controller may be configured to perform an automated tuning method based on analyzing Raman data, as disclosed, for example, in WO2012 / 150434 or WO2014 / 064447.

[0045] It will be understood that modifications and changes may be made to the above embodiments without departing from the present invention as defined herein. For example, other types of filters, such as short-pass filters or notch filters, can be adapted. Quick-release mechanisms, such as those that can be released without tools and / or do not require the release of nuts / bolts, may be provided to allow for the rapid replacement of individual filters 216, 216a, 216b, or the replacement of wheel 229 with a different wheel having at least one different filter. To enable wheel replacement, the wheel and motor shaft may be provided with kinematic mounting structures that allow the wheel to be kinematically mounted on the motor shaft. In this way, mounting of the wheel on the motor shaft in a repeatable position may be facilitated.

Claims

1. A first optical holder for mounting a reflective first optical component, An optical selector comprising a second optical holder for a plurality of second optical components, wherein the second holder is mounted to rotate about a selection axis, and at different angular positions about the selection axis, the second holder positions one of the different selected second optical components in the optical path such that light on the optical input path is directed through the first optical component and the selected second optical component to the optical output path, A mechanism for rotating the selected second optical component while it is in the optical path, and for moving the first optical holder in conjunction with the rotation of the selected second optical component, wherein the light guided along the optical input path is directed along the optical output path at different angular positions of the selected second optical component with respect to the optical output path. An optical mount equipped with [a specific feature].

2. The optical mount according to claim 1, wherein the optical holder comprises a wheel, the selection axis is the wheel axis, and the second optical component is mounted around the wheel axis.

3. The optical mount according to claim 1 or 2, wherein the second optical holder is arranged to mount four or more second optical components.

4. The optical mount according to any one of claims 1 to 3, wherein the second optical holder is mounted such that it rotates the selected second optical component about an incident angle axis perpendicular to the incident plane of the selected second optical component.

5. The optical mount according to claim 4, wherein the incident angle axis intersects with the selected second optical component.

6. The optical mount according to claim 4 or 5, wherein the plane of the optical surface of the selected second optical component is parallel to the angle axis of incidence.

7. The optical mount according to claim 6, wherein the plane of the optical surface of each of the second optical components is parallel to the angle axis of incidence.

8. The optical mount according to any one of claims 4 to 7, relating to claim 2, wherein the incident angle axis is perpendicular to the wheel axis.

9. The optical mount according to claim 8, wherein the incident angle axis intersects with the wheel axis.

10. The optical mount according to any one of claims 1 to 9, comprising a base, wherein the optical selector comprises a support to which the second optical holder is mounted such that the second optical holder can rotate on the support, and the support is mounted on the base so as to rotate relative to the base.

11. The optical mount according to any one of claims 1 to 10, further comprising a motor for rotating the second optical holder.

12. The optical mount according to claim 11, as referenced to claim 2, wherein the wheel is attached to the motor such that the wheel shaft is common with the motor shaft.

13. The optical mount according to any one of claims 1 to 12, wherein the mount comprises a second optical holder encoder for measuring the rotational position of the second optical holder.

14. The optical mount according to claim 13, wherein the second optical holder encoder is an absolute encoder.

15. The optical mount according to any one of claims 1 to 14, wherein the mount comprises a second optical component encoder for measuring the rotational position of the selected second optical component with respect to the optical output path.

16. The optical mount according to claim 15, wherein the second optical component encoder is an absolute encoder.

17. The optical mount according to claim 15 or 16, wherein the second optical component encoder is a linear encoder.

18. The optical mount according to any one of claims 1 to 17, wherein the optical selector comprises a detent for mechanically preventing rotation of the second optical holder at a set position of the second optical holder, and each set position positions one different of the second optical components within the optical path.

19. The optical mount according to claim 18, as referenced to claim 2, wherein the detent comprises a notch in the wheel and a catch that is biased toward the wheel such that the catch engages with the corresponding notch when the notch is aligned with the catch.

20. The optical mount according to any one of claims 1 to 19, wherein each second optical component is kinematically mounted on the second optical holder.

21. The optical mount according to any one of claims 1 to 20, wherein the first optical holder is arranged to mount the first optical component such that the angle of incidence of the light input path to the first optical component is less than 45°.

22. The optical mount according to any one of claims 1 to 21, wherein the plurality of second optical components comprises two or more filters.

23. A spectrometer comprising an optical mount according to any one of claims 1 to 22.

24. The spectrometer according to claim 23, comprising a laser positioned to direct laser light along the optical input path, and an analyzer positioned to receive light transmitted by the selected second optical component.

25. An optical selector comprising a motor having a motor shaft and a wheel attached to the motor shaft, wherein the wheel has mounting portions for attaching a plurality of optical components at circumferential positions centered on the motor shaft axis.

26. The optical selector according to claim 25, comprising a base, wherein the wheel is mounted on the base so as to rotate about the angle axis of incidence.

27. The optical selector according to claim 26, wherein the incident angle axis intersects with the incident surface of a selected optical component among the plurality of optical components positioned on the path of light by the optical selector.

28. The optical selector according to claim 26 or 27, wherein the incident angle axis is perpendicular to the motor shaft axis.

29. The optical selector according to any one of claims 26 to 28, wherein the incident angle axis intersects with the motor shaft axis.

30. The optical selector according to any one of claims 26 to 29, comprising a support on which the wheel is mounted so that the wheel can rotate on the support, the support being mountable to the base so as to rotate relative to the base.

31. An optical selector comprising a wheel mounted to rotate, wherein the wheel comprises a mounting portion for mounting a plurality of optical components at circumferential positions around a rotation axis, and a detent for mechanically preventing the rotation of the wheel relative to a set position, and each set position positions one of the different optical components within the optical path.

32. A spectrometer comprising an optical selector according to any one of claims 25 to 31.

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