JP2011257140A - Spectrograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectrograph that is small and high resolution.SOLUTION: The spectrograph has a spectroscopic optical system that splits incident light into light rays in directions that are different according to wavelengths. The spectroscopic optical system includes: a mirror 13 serving as a deflecting element disposed on a first focusing planar surface 200 and able to change the direction of emission of light made incident on the first focal planar surface 200; a confocal optical system 10 for condensing light, emitted from the mirror 13, on a second focal planar surface 201; a transmission type diffraction grating 16 serving as a dispersive element that splits light passed through the confocal optical system 10, in directions that are different according to wavelengths; and a slit 18 for passing only certain wavelength light of the light rays into which incident light is split by the transmission type diffraction grating 16.

Description

  The present invention relates to a spectrometer capable of measuring light of a predetermined wavelength.

  A spectroscopic optical system that splits incident light in different directions for each wavelength is used as a spectroscope. The configuration of a conventional general spectrometer is shown in FIG. The lens 2 converts light emitted from the optical fiber 1 into collimated light. The dispersive element including the diffraction grating 3 and the like separates the light that has passed through the lens 2 for each wavelength. The lens 4 collects the light dispersed by the dispersive element. The slit 5 allows only light of a single wavelength among the light collected by the lens 4 to pass. The PD (photodiode) 6 receives the light that has passed through the slit 5 and converts it into an electrical signal. In this spectroscope, the wavelength of light received by the PD 6 can be changed by rotating the dispersive element (see, for example, Patent Document 1). In such a spectroscope, the equation indicating the resolution is as follows.

  Here, Δλ is the resolution, λ is the wavelength of light, ω is the beam radius, that is, the minimum radius of the dispersion element, dθ / dλ is the dispersion capability of the dispersion element, and k is a constant. In order to realize a high resolution of the spectroscope (that is, to reduce Δλ), it is necessary to increase the size of the dispersive element (that is, increase ω) or to increase the dispersive ability dθ / dλ of the dispersive element. However, when a large dispersion element is used, the weight and area of the dispersion element increase. Therefore, in order to rotate the dispersion element, it is necessary to use a large drive system with a low driving speed and a large output. Alternatively, when an immersion grating having a prism attached to a diffraction grating (Immersion grating, see, for example, Non-Patent Document 1) is used as a dispersive element having high dispersibility, the immersion grating is larger than the diffraction grating. Again, similar problems occur in the drive system.

As described above, the conventional spectrometer configuration has a problem that if the resolution is increased, the drive system necessary for the wavelength sweep using the dispersive element becomes large, and the spectrometer becomes large. It was.
Thus, a spectroscope in which a rotatable reflecting mirror is arranged in front of the dispersive element has also been proposed. The configuration of such a spectroscope is shown in FIG. The lens 322 converts light emitted from the optical fiber 321 into collimated light. The rotatable mirror 323 reflects the light that has passed through the lens 322. The dispersive element 324 separates the reflected light from the mirror 323 for each wavelength. The lens 325 collects the light separated by the dispersive element 324. The slit 326 passes only light having a single wavelength among the light collected by the lens 325. The PD 327 receives the light that has passed through the slit 326 and converts it into an electrical signal.

  In the case of the configuration of the spectroscope shown in FIG. 11, since the dispersion element 324 is a fixed element, there is no problem even if it is heavy. However, when light is deflected by the mirror 323 and wavelength swept, light is incident on the surface of the dispersion element 324. Because the position changes, the effective size of the dispersive element 324 must be increased. When the size of the dispersive element 324 is increased, it becomes difficult to ensure the in-plane uniformity of the dispersive element 324, and there is a problem that the resolution of the spectroscope is deteriorated due to the influence of warpage or the like.

JP-A-11-183249

Gunter Wiedemann and Donald E. Jennings, “Immersion grating for infrared astronomy”, Applied Optics, vol.32, no.7, 1993

As described above, the configuration of the spectrometer shown in FIG. 10 has a problem that the spectrometer becomes large in order to increase the resolution.
Further, the configuration of the spectrometer shown in FIG. 11 has a problem that the resolution deteriorates.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a compact and high-resolution spectrometer.

The spectroscope according to the present invention includes a spectroscopic optical system that splits incident light in different directions for each wavelength, and the spectroscopic optical system is disposed on a first focal plane and emits light incident on the first focal plane. A deflecting element capable of changing the direction, a confocal optical system for condensing the light emitted from the deflecting element on a second focal plane, and disposed on the second focal plane and passing through the confocal optical system It is characterized by comprising a dispersive element that disperses the emitted light in a different direction for each wavelength, and a slit that allows passage of only light having a part of the wavelength of the light dispersed by the dispersive element.
Moreover, in one configuration example of the spectroscope (first and second embodiments) of the present invention, the spectroscopic optical system further includes a front focal point between the dispersive element and the slit. The first lens or the first curved mirror is disposed so as to coincide with the dispersion surface and the rear focal point coincides with the center of the slit, and the confocal optical system includes at least second and third 2 It is characterized by comprising two lenses or second and third curved mirrors.

In one configuration example of the spectroscope (fifth embodiment) of the present invention, the dispersive element is a reflective diffraction grating, and the confocal optical system includes at least first and second lenses. Alternatively, the first and second curved mirrors are used, and the slit is located between the first and second lenses or between the first and second curved mirrors. Light that is disposed on the focal plane of the curved mirror and that enters the first lens or the first curved mirror from the deflection element, and light that enters the dispersion element from the second lens or the second curved mirror Each is characterized in that the position or angle is offset with respect to the optical axis of the confocal optical system.
In one configuration example of the spectroscope of the present invention (sixth embodiment), the slit is provided in a partial region of the mirror, and the light from the deflection element is reflected by the mirror. In this case, only light having a part of the wavelength of the light incident on the dispersion element and dispersed by the dispersion element passes through the slit.

In one configuration example of the spectroscope of the present invention (seventh embodiment), the spectroscopic optical system further includes a front focal point between the dispersion element and the slit, and a dispersion surface of the dispersion element. The first lens or the first curved mirror is arranged so that the rear focal point coincides with the center of the slit, and the confocal optical system includes at least the second and third lenses or The second and third curved mirrors are used, and the light incident on the deflecting element is located between the second and third curved lenses or the second and third curved mirrors. Light emitted from a fiber having a light exit end disposed on the focal planes of two curved mirrors and incident on the deflection element from the second lens or second curved mirror is an optical axis of the confocal optical system. With respect to position or angle And it is characterized in that it is offset.
In one configuration example of the spectroscope of the present invention (eighth and ninth embodiments), the confocal optical system includes one lens or a curved mirror and the lens or curved mirror reflected by the deflecting element. Is reflected in the direction of the lens or curved mirror and is incident on the dispersive element. The dispersive element is a reflective diffraction grating, and the deflection element and the dispersive element are: The mirror or the slit is disposed on the other focal plane of the lens or curved mirror, passes through the lens or curved mirror, and is deflected. The light incident on the element is emitted from a fiber having a light exit end disposed on the other focal plane of the lens or curved mirror. A.

In one configuration example of the spectroscope (third embodiment) of the present invention, the second lens closer to the deflection element among the two lenses or two curved mirrors constituting the confocal optical system. The focal length of the third lens or the third curved mirror closer to the dispersion element is longer than the focal length of the lens or the second curved mirror, and the deflection element is a MEMS mirror. It is.
In one configuration example of the spectroscope (fourth embodiment) of the present invention, the second lens or the second curved mirror on the side close to the deflection element of the two confocal optical systems. The focal length of the third lens or third curved mirror closer to the dispersive element is shorter than the focal length of the lens or second curved mirror, and the deflecting element is liquid crystal or LCOS. Is.

  According to the present invention, the spectroscopic optical system is disposed on the first focal plane, the deflection element capable of changing the emission direction of the light incident on the first focal plane, and the second light emitted from the deflection element. Consists of a confocal optical system that focuses light on the focal plane and a dispersive element that is arranged on the second focal plane and separates the light that has passed through the confocal optical system in different directions for each wavelength. The change in the irradiation position of the light can be reduced, and the resolution of the spectrometer can be increased without increasing the dispersive element. In the present invention, it is not necessary to turn a large dispersion element by changing the dispersion wavelength by changing the incident angle of light to the dispersion element by the deflecting element. As a result, in the present invention, it is possible to realize a spectroscopic optical system that does not require a dispersive element driving device while suppressing an increase in effective diameter of the dispersive element, and realizes a small, high-resolution and low-cost spectroscope. can do.

  In the present invention, the dispersive element is a reflective diffraction grating, the confocal optical system is composed of at least first and second lenses or first and second curved mirrors, and the slits are first, From the second lens or the second curved mirror disposed on the focal plane of the second lens or the first and second curved mirrors, the light incident on the first lens or the first curved mirror from the deflecting element and the second lens or the second curved mirror The spectroscope can be further miniaturized by shifting the position or angle of each light incident on the dispersive element with respect to the optical axis of the confocal optical system.

  In the present invention, a slit is provided in a part of the mirror, and the light from the deflecting element is reflected by the mirror and incident on the dispersive element. The spectroscope can be further miniaturized by allowing only the light of the light to pass through the slit.

  In the present invention, the confocal optical system is configured by at least the second and third lenses or the second and third curved mirrors, and the light incident on the deflecting element is converted into the second and third lenses. A confocal optical system emits light that is emitted from a lens or a fiber having a light exit end disposed on the focal plane of the second and third curved mirrors and is incident on the deflection element from the second lens or second curved mirror. The spectroscope can be further miniaturized by shifting the position or angle with respect to the optical axis.

  In the present invention, the confocal optical system includes a single lens or curved mirror, and a mirror that reflects the light reflected by the deflection element and passed through the lens or curved mirror in the direction of the lens or curved mirror and enters the dispersion element. The dispersive element is a reflective diffraction grating, the deflecting element and the dispersive element are arranged on one focal plane of the lens or curved mirror, and the mirror and slit are arranged on the other focal plane of the lens or curved mirror The spectroscope is further reduced in size by emitting light that passes through the lens or curved mirror and enters the deflecting element from a fiber that has a light exit end on the other focal plane of the lens or curved mirror. Can be

  In the present invention, of the two lenses or two curved mirrors constituting the confocal optical system, the second lens closer to the deflecting element or the side closer to the dispersive element than the focal length of the second curved mirror By increasing the focal length of the third lens or the third curved mirror, it is possible to reduce the beam diameter on the deflecting element while maintaining the beam diameter on the dispersive element surface. Small MEMS mirrors can be used.

  In the present invention, of the two lenses or two curved mirrors constituting the confocal optical system, the second lens closer to the deflecting element or the side closer to the dispersive element than the focal length of the second curved mirror By shortening the focal length of the third lens or the third curved mirror, the deflection angle width of the deflection element can be reduced while maintaining the deflection angle width of the dispersion element surface. A liquid crystal or LCOS can be used.

It is a block diagram which shows the structure of the spectrometer which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 5th Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 6th Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 7th Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 8th Embodiment of this invention. It is a block diagram which shows the structure of the spectrometer which concerns on the 9th Embodiment of this invention. It is a block diagram which shows the structure of the conventional spectrometer. It is a block diagram which shows the structure of the other conventional spectrometer.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the spectrometer according to the first embodiment of the present invention. The spectroscope according to the present embodiment includes a fiber 11, a first lens 12, a rotatable mirror 13 that serves as a deflection element, a second lens 14, a third lens 15, and a transmission diffraction that serves as a dispersion element. It comprises a grating 16, a fourth lens 17, a slit 18, and a PD (photodiode) 19 serving as a light receiving element.

  The first lens 12 is disposed so that the front focal point coincides with the light emitting end f <b> 11 of the fiber 11 and the rear focal point coincides with the reflecting surface f <b> 12 of the mirror 13. The second lens 14 is disposed such that the front focal point coincides with the reflecting surface f12 of the mirror 13 and the rear focal point coincides with the intermediate point f13 between the lenses 14 and 15. The third lens 15 is arranged so that the front focal point coincides with the intermediate point f13 between the lenses 14 and 15, and the rear focal point coincides with the diffraction surface f14 of the transmissive diffraction grating 16. The fourth lens 17 is arranged such that the front focal point coincides with the diffraction surface f14 of the transmission diffraction grating 16 and the rear focal point coincides with the center point f15 of the slit 18.

  The first lens 12 converts light from the fiber 11 serving as a light emitting end into collimated light. A mirror 13 that is rotatable about a rotation axis 20 that is perpendicular to the direction from the fiber 11 toward the mirror 13 and perpendicular to the optical axis of a confocal optical system (to be described later). Reflects light that has passed through the first lens 12. The second and third lenses 14 and 15 collect the reflected light from the mirror 13.

  The transmissive diffraction grating 16 splits the light collected by the second and third lenses 14 and 15 in different directions for each wavelength. The fourth lens 17 condenses the light separated by the transmissive diffraction grating 16. The slit 18 allows only light of a single wavelength out of the light collected by the fourth lens 17. The PD 19 receives the light that has passed through the slit 18 and converts it into an electrical signal.

  In the configuration as described above, the second lens 14 and the third lens 15 cause the light that has passed through the first focal plane 200 (the reflection surface f12 of the mirror 13) to pass through the second focal plane 201 (diffracted by the transmission diffraction grating 16). A confocal optical system 10 for condensing light on the surface f14) is formed. The spectroscope of the present embodiment is a monochromator that receives only light having a wavelength that passes through the slit 18 among the light in which incident light is dispersed by the transmission diffraction grating 16 that is a dispersive element, by the PD 19.

  In the present embodiment, the transmissive diffraction grating 16 is disposed on the front focal plane of the fourth lens 17, and the slit 18 is disposed on the rear focal plane of the fourth lens 17. The optical axis direction of the light passing through the first focal plane 200 can be changed by rotating the mirror 13 which is a deflection element arranged on the first focal plane 200 by a driving mechanism (not shown), and the second focal plane Since the angle of light incident on the transmissive diffraction grating 16, which is a dispersive element arranged at 201, can be changed, the wavelength of light passing through the slit 18 can be changed.

  In the present embodiment, by arranging the transmission type diffraction grating 16 at the focal position of the confocal optical system 10, the angle of light incident on the diffraction surface of the transmission type diffraction grating 16 is changed by the rotation of the mirror 13. However, since the incident position of the light on the diffraction surface of the transmission type diffraction grating 16 does not change, the resolution of the spectrometer can be increased without increasing the size of the transmission type diffraction grating 16.

  In the present embodiment, the transmissive diffraction grating 16 is used as the dispersive element, but a reflective diffraction grating may be used. If a fiber collimator is used instead of the fiber 11, the first lens 12 is not necessary. In the present embodiment, the confocal optical system 10 is configured by the two lenses 14 and 15. However, the confocal optical system 10 is not limited to the two lenses, but includes two curved mirrors, a plurality of lenses, and a plurality of curved surfaces. You may comprise with a mirror. A curved mirror may be used instead of the lens 17.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. This embodiment shows a modification of the first embodiment. FIG. 2 is a block diagram showing the configuration of the spectrometer according to the present embodiment. The spectroscope of the present embodiment includes a fiber 121, a first curved mirror 122, a rotatable mirror 123 serving as a deflecting element, a second curved mirror 124, a third curved mirror 125, a diffraction grating, and a prism. Are composed of an immersion grating 126, a fourth curved mirror 127, a slit 128, and a PD 129. The immersion grating is a kind of reflection type diffraction grating.

  The first curved mirror 122 is arranged such that the front focal point coincides with the light emitting end f 121 of the fiber 121 and the rear focal point coincides with the reflecting surface f 122 of the mirror 123. The second curved mirror 124 is arranged such that the front focal point coincides with the reflecting surface f122 of the mirror 123 and the rear focal point coincides with the intermediate point f123 between the curved mirrors 124 and 125. The third curved mirror 125 is arranged such that the front focal point coincides with the intermediate point f123 between the curved mirrors 124 and 125, and the rear focal point coincides with the diffraction surface f124 of the immersion grating 126. The fourth curved mirror 127 is arranged such that the front focal point coincides with the diffraction surface f124 of the immersion grating 126 and the rear focal point coincides with the intermediate point f125 of the slit 128.

  The first curved mirror 122 reflects light from the fiber 121 serving as a light emitting end. An axis perpendicular to the direction from the fiber 121 toward the first curved mirror 122 and perpendicular to the optical axis of a confocal optical system (to be described later) (axis perpendicular to the paper surface of FIG. 2) can be rotated as a rotation axis 130. The mirror 123 reflects the reflected light from the first curved mirror 122. The second curved mirror 124 reflects the reflected light from the mirror 123, and the third curved mirror 125 reflects the reflected light from the second curved mirror 124.

  The immersion grating 126 splits the reflected light from the third curved mirror 125 in different directions for each wavelength. The fourth curved mirror 127 reflects the light dispersed by the immersion grating 126. The slit 128 allows only light having a single wavelength out of the reflected light from the fourth curved mirror 127. The PD 129 receives the light that has passed through the slit 128 and converts it into an electrical signal.

  In the configuration as described above, the second curved mirror 124 and the third curved mirror 125 allow the light that has passed through the first focal plane (the reflection surface f122 of the mirror 123) to pass through the second focal plane (the diffraction plane f124 of the immersion grating 126). ) Is a confocal optical system. The spectroscope of the present embodiment is a monochromator that receives only light having a wavelength that passes through the slit 128 among the light in which incident light is dispersed by the immersion grating 126 that is a dispersive element, by the PD 129.

  In the present embodiment, the optical axis direction of the light passing through the first focal plane can be changed by rotating the mirror 123, which is a deflection element arranged on the first focal plane, by a drive mechanism (not shown). Since the angle of light incident on the immersion grating 126 which is a dispersive element disposed on the second focal plane can be changed, the wavelength of light passing through the slit 128 can be changed. For this reason, in this embodiment, the resolution of the spectrometer can be increased without increasing the immersion grating 126.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 3 is a block diagram showing a configuration of a spectrometer according to the third embodiment of the present invention. The same reference numerals are given to the same configurations as those in FIG. The spectroscope according to the present embodiment includes a fiber 11, a first lens 12, a rotatable mirror 13 serving as a deflection element, a second lens 14a, a third lens 15a, and a transmission type diffraction serving as a dispersion element. The grating 16, the fourth lens 17, the slit 18, and the PD 19 are included.

  The configuration of the spectrometer of the present embodiment is the same as that of the first embodiment, but the focal lengths of the second lens 14a and the third lens 15a constituting the confocal optical system 10 are the same as those of the first embodiment. Different. In the first embodiment, the focal lengths of the second lens 14 and the third lens 15 are the same. On the other hand, in the present embodiment, the second lens 14a is disposed such that the front focal point coincides with the reflecting surface f12 of the mirror 13, and the rear focal point coincides with the point f130 on the front side of f13. The three lenses 15a are arranged such that the front focal point coincides with the point f130 and the rear focal point coincides with the diffraction surface f14 of the transmissive diffraction grating 16.

  That is, if the focal length of the second lens 14a is f134 and the focal length of the third lens 15a is f135, f134 <f135, and the focal length ratio (f134 / f135) is a value smaller than 1. At this time, assuming that the beam diameter on the mirror 13 is ω133 and the beam diameter on the transmissive diffraction grating 16 is ω136, the relationship between the beam diameters ω133 and ω136 is as follows.

  As is apparent from the equation (2), in this embodiment, the focal length ratio (f134 / f135) is set to a value smaller than 1, so that the beam diameter of the dispersion element surface determined by the resolution is maintained and the mirror is maintained. Since the beam diameter on 13 can be reduced, a mirror (for example, a MEMS (Microelectro-Mechanical Systems) mirror) having a large deflection angle but a small area can be used as the deflecting element.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 4 is a block diagram showing a configuration of a spectrometer according to the fourth embodiment of the present invention. The same reference numerals are given to the same configurations as those in FIG. The spectroscope according to the present embodiment includes a fiber 11, a first lens 12, a rotatable mirror 13 serving as a deflection element, a second lens 14b, a third lens 15b, and a transmission type diffraction serving as a dispersion element. The grating 16, the fourth lens 17, the slit 18, and the PD 19 are included.

  The configuration of the spectrometer of the present embodiment is the same as that of the first embodiment, but the focal lengths of the second lens 14b and the third lens 15b constituting the confocal optical system 10 are the same as those of the first embodiment. Different. The second lens 14b is arranged so that the front focal point coincides with the reflection surface f12 of the mirror 13, the rear focal point coincides with the point f140 on the rear side of f13, and the third lens 15b has the front focal point at the point f140. And the rear focal point coincides with the diffraction surface f14 of the transmissive diffraction grating 16.

  That is, if the focal length of the second lens 14b is f144 and the focal length of the third lens 15b is f145, then f144> f145, and the focal length ratio (f144 / f145) is a value larger than 1. At this time, assuming that the beam diameter on the mirror 13 is ω143, the beam deflection angle is Δθ143, the beam diameter on the transmission diffraction grating 16 is ω146, and the beam deflection angle is Δθ146, the beam diameters ω143 and ω146 The relationship between the deflection angles Δθ143 and Δθ146 is as shown in the following equations.

  In the present embodiment, by setting the focal length ratio (f145 / f144) to a value smaller than 1, the deflection angle width of the mirror 13 is maintained while maintaining the deflection angle width of the dispersion element surface determined by the wavelength sweep width. Therefore, a mirror having a small deflection angle (for example, liquid crystal or LCOS (Liquid Crystal On Silicon)) can be used as the deflecting element. In this embodiment, as can be seen from Equation (3), the beam diameter ω143 on the mirror 13 is larger than in the first embodiment, but in LCOS, small drive elements are arrayed in a large area. Since it is a thin device, there is no problem even if the beam diameter ω143 is increased.

  As is clear from the present embodiment, there is a trade-off relationship between the beam diameter on the mirror 13 and the width of the deflection angle, and the focal length ratio (f145 / f144), that is, confocal, depends on the driving element such as LCOS. It is necessary to set the optical system magnification to an optimum value.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. FIGS. 5A and 5B are block diagrams showing the configuration of the spectrometer according to the fifth embodiment of the present invention, and FIG. 5A is a diagram of the spectrometer as viewed from above, FIG. FIG. 5B is a view of the spectroscope as viewed from the side. The spectroscope according to the present embodiment includes a fiber 21, a first lens 22, a rotatable mirror 23 serving as a deflection element, a second lens 24, a third lens 25, and a dispersion of a reflection type diffraction grating. It is comprised from the element 26, the slit 27, and PD28.

  The first lens 22 is arranged so that the front focal point coincides with the light emitting end f <b> 21 of the fiber 21 and the rear focal point coincides with the reflecting surface f <b> 22 of the mirror 23. The second lens 24 is arranged such that the front focal point coincides with the reflection surface f22 of the mirror 23 and the rear focal point coincides with the center point f23 of the slit 27. The third lens 25 is arranged such that the front focal point coincides with the center point f23 of the slit 27 and the rear focal point coincides with the dispersion surface f24 of the dispersion element 26.

  The first lens 22 converts light from the fiber 21 serving as a light emitting end into collimated light. An axis perpendicular to the direction from the fiber 21 to the mirror 23 and perpendicular to the optical axis of the confocal optical system (to be described later) (axis perpendicular to the paper surface of FIG. 5A) can be rotated as the rotation axis 30. The mirror 23 reflects the light that has passed through the first lens 22. The second and third lenses 24 and 25 collect the reflected light from the mirror 23.

  The dispersive element 26 separates the light collected by the second and third lenses 24 and 25 in different directions for each wavelength. Here, for example, since a reflection type diffraction grating is used as the dispersion element 26, the dispersion element 26 reflects incident light in different directions for each wavelength. The third lens 25 condenses the light separated by the dispersive element 26. The slit 27 allows only light of a single wavelength among the light collected by the third lens 25 to pass. The PD 28 receives the light that has passed through the slit 27 and converts it into an electrical signal.

  In the present embodiment, the second lens 24 and the third lens 25 collect light that has passed through the first focal plane (the reflection surface f22 of the mirror 23) on the second focal plane (the dispersion surface f24 of the dispersion element 26). A confocal optical system that emits light is formed. 5B, the second lens 24 and the third lens 25 are offset in parallel so that the light incident on the third lens 25 and the emitted light do not overlap. The light incident on the third lens 25 and the light emitted are not parallel to the optical axis 29 of the confocal optical system.

  This offset is realized by making the light incident on the second lens 24 from the mirror 23 and the light incident on the dispersion element 26 from the third lens 25 non-parallel to the optical axis 29 of the confocal optical system. can do. Even if the center of the mirror 23 and the center of the dispersive element 26 are displaced from the optical axis 29 of the confocal optical system, the light incident on the third lens 25 is emitted between the second lens 24 and the third lens 25. There is no problem in configuration, just that the light is not parallel to the axis 29. The slit 27 and the PD 28 are disposed on the focal planes of the second lens 24 and the third lens 25.

  In the present embodiment, similarly to the first embodiment, the mirror 23 which is a deflection element arranged on the first focal plane is rotated by a driving mechanism (not shown), so that the light passing through the first focal plane is reflected. The direction of the optical axis can be changed, and the angle of light incident on the dispersion element 26 disposed on the second focal plane can be changed, so that the wavelength of light passing through the slit 27 can be changed.

  The feature of this embodiment is that the number of lenses can be reduced and each element can be densely arranged as compared with the first embodiment. As a result, in this embodiment, the spectrometer can be further downsized. In the present embodiment, the confocal optical system is configured with two lenses 24 and 25, but is not limited to two lenses, and is configured with two curved mirrors, a plurality of lenses, and a plurality of curved mirrors. May be.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. FIGS. 6A and 6B are block diagrams showing the configuration of a spectrometer according to the sixth embodiment of the present invention, and FIG. 6A is a diagram of the spectrometer as viewed from above, FIG. 6 (B) is a view of the spectroscope viewed from the side. The spectroscope according to the present embodiment includes a fiber collimator 221, a rotatable mirror 222 serving as a deflecting element, a first lens 223, a mirror with slit 224, a second lens 225, a reflective diffraction grating, and the like. The dispersion element 226 and the PD 227 are included.

  The first lens 223 is disposed such that the front focal point coincides with the reflecting surface f221 of the mirror 222 and the rear focal point coincides with the reflecting surface f222 of the mirror with slit 224. The second lens 225 is disposed such that the front focal point coincides with the reflecting surface f222 of the mirror with slit 224 and the rear focal point coincides with the dispersion surface f223 of the dispersion element 226.

  A rotation axis 230 is an axis that is perpendicular to the direction from the fiber collimator 221 to the mirror 222 and perpendicular to the optical axis of the confocal optical system described later (an axis perpendicular to the paper surface of FIG. 6A). A possible mirror 222 reflects the collimated light emitted from the fiber collimator 221. The first lens 223 collects the reflected light from the mirror 222. The slit mirror 224 reflects the light collected by the first lens 223. The second lens 225 collects the reflected light from the slit mirror 224.

  The dispersive element 226 separates the light collected by the second lens 225 in different directions for each wavelength. Here, for example, since a reflection type diffraction grating is used as the dispersion element 226, the dispersion element 226 reflects incident light in different directions for each wavelength. The second lens 225 collects the light dispersed by the dispersive element 226. The slit mirror 224 passes only light having a single wavelength among the light collected by the second lens 225. The PD 227 receives the light that has passed through the slit mirror 224 and converts it into an electrical signal.

  In the present embodiment, the first lens 223 and the second lens 225 collect light that has passed through the first focal plane (the reflection surface f221 of the mirror 222) on the second focal plane (the dispersion surface f223 of the dispersion element 226). A confocal optical system that emits light is formed. And between the 2nd lens 225 and the mirror 224 with a slit, it is offset in parallel so that the light which injects into the 2nd lens 225, and the emitted light may not overlap. This offset is realized by making the light incident on the first lens 223 from the mirror 222 and the light incident on the dispersion element 226 from the second lens 225 non-parallel to the optical axis 228 of the confocal optical system. it can.

  A feature of the optical system according to the present embodiment is that a slit mirror 224 is used. Before entering the dispersion element 226, light from the mirror 222 enters the reflection surface of the slit mirror 224, and the dispersion element. After entering the H.226, the light having a specific wavelength out of the light from the dispersive element 226 passes through the slit of the slit mirror 224. The slit mirror 224 and the PD 227 are disposed on the focal plane of the second lens 225.

  In the present embodiment, similarly to the first embodiment, the mirror 222, which is a deflection element arranged on the first focal plane, is rotated by a driving mechanism (not shown) so that the light passing through the first focal plane is reflected. The optical axis direction can be changed, and the angle of light incident on the dispersive element 226 disposed on the second focal plane can be changed, so that the wavelength of light passing through the slit 227 can be changed.

  The feature of this embodiment is that the number of lenses is reduced compared to the first embodiment, and an optical element is arranged using a mirror with slit 224 which is a bending mirror. As a result, in this embodiment, the spectrometer can be further downsized. Instead of the fiber collimator 221, a fiber and a collimator lens may be used.

[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described. FIGS. 7A and 7B are block diagrams showing the configuration of a spectrometer according to the seventh embodiment of the present invention, and FIG. 7A is a diagram of the spectrometer as viewed from above, FIG. 7 (B) is a view of the spectroscope from the side. The spectroscope of this embodiment includes a fiber 31, a first lens 32, a rotatable mirror 33 serving as a deflection element, a second lens 34, a dispersion element 35 such as a transmission diffraction grating, and a third element. The lens 36, the slit 37, and the PD 38 are included.

  The first lens 32 is arranged such that one focal point coincides with the intermediate point f31 between the lenses 32 and 34 and the other focal point coincides with the reflecting surface f32 of the mirror 33. The second lens 34 is arranged such that the front focal point coincides with the intermediate point f31 between the lenses 32 and 34 and the rear focal point coincides with the dispersion surface f33 of the dispersion element 35. The third lens 36 is disposed so that the front focal point coincides with the dispersion surface f33 of the dispersive element 35 and the rear focal point coincides with the center point f34 of the slit 37.

  The light emitted from the fiber 31 and passing through the first lens 32 enters the mirror 33. The rotatable mirror 33 reflects the light that has passed through the first lens 32. Note that the rotation axis 40 of the mirror 33 of the present embodiment is inclined with respect to the optical axis of the confocal optical system. The second lens 34 collects the light reflected by the mirror 33 and passed through the first lens 32. The second lens 34 also serves as a collimating lens.

  The dispersive element 35 separates the light collected by the second lens 34 in different directions for each wavelength. The third lens 36 condenses the light separated by the dispersive element 35. The slit 37 allows only light having a single wavelength to pass through the light collected by the third lens 36. The PD 38 receives the light that has passed through the slit 37 and converts it into an electrical signal.

  In the present embodiment, the first lens 32 and the second lens 34 collect light that has passed through the first focal plane (the reflection surface f32 of the mirror 33) on the second focal plane (the dispersion surface f33 of the dispersion element 35). A confocal optical system that emits light is formed. 7B, the fiber 31 is disposed on the focal planes of the first lens 32 and the second lens 34, and is disposed at a position deviated from the straight line connecting the mirror 33 and the dispersion element 35. . The first lens 32 and the second lens 34 are offset in parallel so that the light incident on the first lens 32 and the emitted light do not overlap. This offset can be realized by making light incident on the mirror 33 from the first lens 32 non-parallel to the optical axis 39 of the confocal optical system.

  In the present embodiment, similarly to the first embodiment, the mirror 33, which is a deflection element arranged on the first focal plane, is rotated by a driving mechanism (not shown) so that the light passing through the first focal plane is reflected. The optical axis direction can be changed, and the angle of light incident on the dispersion element 35 disposed on the second focal plane can be changed, so that the wavelength of light passing through the slit 37 can be changed. The feature of this embodiment is that the number of lenses is reduced as compared to the first embodiment. As a result, in this embodiment, the spectrometer can be further downsized. In the present embodiment, the confocal optical system is configured by the two lenses 32 and 34, but is not limited to the two lenses, and is configured by two curved mirrors, a plurality of lenses, and a plurality of curved mirrors. May be. A curved mirror may be used instead of the lens 36.

[Eighth Embodiment]
Next, an eighth embodiment of the present invention will be described. FIGS. 8A and 8B are block diagrams showing the configuration of the spectrometer according to the eighth embodiment of the present invention, and FIG. 8A is a diagram of the spectrometer viewed from above, FIG. 8 (B) is a view of the spectroscope as viewed from the side. The spectroscope of the present embodiment includes a fiber 41, a first lens 42, a rotatable mirror 43 serving as a deflection element, a mirror 44, a dispersion element 45 such as a reflective diffraction grating, a slit 46, It consists of PD47.

The first lens 42 is arranged such that one focal point coincides with the light emitting end f41 of the fiber 41 and the other focal point coincides with the reflecting surface f42 of the mirror 43.
The light emitted from the fiber 41 and passing through the first lens 42 enters the mirror 43. The mirror 43 that can be rotated about an axis perpendicular to the optical axis of a confocal optical system (to be described later) (an axis perpendicular to the paper surface of FIG. To reflect. The mirror 44 reflects the light reflected by the mirror 43 and passed through the first lens 42.

  The dispersive element 45 separates the light reflected by the mirror 44 and passed through the first lens 42 in different directions for each wavelength. Here, for example, a reflective diffraction grating is used as the dispersive element 45, so the dispersive element 45 reflects incident light in different directions for each wavelength. The slit 46 transmits only light having a single wavelength out of the light reflected by the dispersion element 45 and passing through the first lens 42. The PD 47 receives the light that has passed through the slit 46 and converts it into an electrical signal.

  In the present embodiment, the first lens 42 and the mirror 44 are configured to condense light that has passed through the first focal plane (the reflection surface f42 of the mirror 43) onto the second focal plane (the dispersion surface of the dispersion element 45). A focusing optical system is configured. Then, the light that enters the mirror 43 and the light that exits are angularly offset with respect to the optical axis 48 of the confocal optical system, so that the light traveling from the fiber 41 to the first lens 42 and the first lens 42 to the mirror 44 are offset. The incoming light is offset in parallel. Further, the light entering the dispersion element 45 and the outgoing light are angularly offset with respect to the optical axis 48 of the confocal optical system, so that the light traveling from the mirror 44 toward the first lens 42 and the slit 46 from the first lens 42 are obtained. The light heading toward is offset in parallel. These two angular offsets may be orthogonal in direction.

  The fiber 41, the mirror 44, the slit 46, and the PD 47 are disposed on one focal plane of the first lens 42, and the dispersion element 45 and the mirror 43 are disposed on the other focal plane of the first lens 42. The

  In the present embodiment, as in the first embodiment, the optical axis direction of the light can be changed by rotating the mirror 43 that is a deflection element by a drive mechanism (not shown), and the dispersion element 45 can be changed. Since the angle of the incident light can be changed, the wavelength of the light passing through the slit 46 can be changed. The feature of this embodiment is that the number of lenses is reduced as compared to the first embodiment. As a result, in this embodiment, the spectrometer can be further downsized. In this embodiment, the confocal optical system is configured by the lens 42 and the mirror 44, but a curved mirror may be used instead of the lens 42.

[Ninth Embodiment]
Next, a ninth embodiment of the present invention will be described. 9A and 9B are block diagrams showing the configuration of a spectrometer according to the ninth embodiment of the present invention, and FIG. 9A is a diagram of the spectrometer viewed from above, FIG. 9B is a diagram of the spectroscope as viewed from the side. The spectroscope of the present embodiment includes a fiber 51, a first lens 52, a rotatable mirror 53 serving as a deflecting element, a mirror 54, a dispersion element 55 such as a reflective diffraction grating, a slit 56, It is comprised from PD57. In the present embodiment, the positions of the mirror 53 and the dispersion element 55 are interchanged with respect to the eighth embodiment.

In the present embodiment, the first lens 52 and the mirror 54 confocalize the light that has passed through the first focal plane (the reflective surface of the mirror 53) onto the second focal plane (the dispersion surface of the dispersion element 55). An optical system is configured.
The first lens 52 has one focal point that coincides with the intersection f51 between the reflecting surface of the mirror 54 and the optical axis 58 of the confocal optical system, and the other focal point is in common with a plane including the first and second focal planes. They are arranged so as to coincide with the intersection f52 with the optical axis 58 of the focus optical system.

  The light emitted from the fiber 51 and passing through the first lens 52 enters the mirror 53. The mirror 53 that can rotate about an axis perpendicular to the optical axis of a confocal optical system (to be described later) (axis perpendicular to the paper surface of FIG. 9A) as the rotation axis 60 is light that has passed through the first lens 52. To reflect. The mirror 54 reflects the light reflected by the mirror 53 and passed through the first lens 52.

  The dispersive element 55 disperses the light reflected by the mirror 54 and passed through the first lens 52 in different directions for each wavelength. Here, for example, a reflective diffraction grating is used as the dispersive element 55, so that the dispersive element 55 reflects incident light in different directions for each wavelength. The slit 56 passes only light having a single wavelength among the light reflected by the dispersion element 55 and passed through the first lens 52. The PD 57 receives the light that has passed through the slit 56 and converts it into an electrical signal.

  In the present embodiment, the light that enters the mirror 53 and the light that exits are angularly offset so that the light traveling from the fiber 51 toward the first lens 52 and the light traveling from the first lens 52 toward the mirror 54 are offset in parallel. I am letting. Even if the center of the mirror 53 is deviated from the optical axis 58 of the confocal optical system, the light traveling from the fiber 51 toward the first lens 52 and the light traveling from the first lens 52 toward the mirror 54 are not relative to the optical axis 58. It just becomes parallel. Further, the light entering the dispersive element 55 and the outgoing light are angularly offset, so that the light traveling from the mirror 54 toward the first lens 52 and the light traveling from the first lens 52 toward the slit 56 are offset in parallel. . Even if the center of the dispersive element 55 is shifted from the optical axis 58 of the confocal optical system, the light traveling from the mirror 54 toward the first lens 52 and the light traveling from the first lens 52 toward the slit 56 are It just becomes non-parallel.

  In the present embodiment, similarly to the first embodiment, the optical axis direction of the light can be changed by rotating the mirror 53 that is a deflection element by a drive mechanism (not shown), and the dispersion element 55 can be changed. Since the angle of the incident light can be changed, the wavelength of the light passing through the slit 56 can be changed. According to the present embodiment, the same effect as in the eighth embodiment can be obtained. In the present embodiment, the confocal optical system is configured by the lens 52 and the mirror 54, but a curved mirror may be used instead of the lens 52.

  The present invention can be applied to a technique for splitting light.

  11, 21, 31, 41, 51, 121 ... fiber, 12, 14, 14a, 14b, 15, 15a, 15b, 17, 22, 24, 25, 32, 34, 36, 42, 52, 223, 225 ... Lens, 13, 23, 33, 43, 44, 53, 54, 123, 222 ... mirror, 16 ... transmission diffraction grating, 18, 27, 37, 46, 56, 128 ... slit, 19, 28, 38, 47 , 57, 129, 227 ... photodiodes, 26, 35, 45, 55, 226 ... dispersion elements, 122, 124, 125, 127 ... curved mirrors, 126 ... immersion gratings, 221 ... fiber collimators, 224 ... mirrors with slits.

Claims (8)

Has a spectroscopic system that splits incident light in different directions for each wavelength,
The spectroscopic optical system is
A deflection element disposed on the first focal plane and capable of changing the exit direction of the light incident on the first focal plane;
A confocal optical system for condensing the light emitted from the deflecting element on the second focal plane;
A dispersive element that is disposed on the second focal plane and separates light that has passed through the confocal optical system in different directions for each wavelength;
A spectroscope comprising: a slit that allows passage of only light having a part of the wavelength of light dispersed by the dispersive element. The spectrometer of claim 1, wherein
The spectroscopic optical system is further arranged between the dispersive element and the slit such that a front focal point coincides with a dispersive surface of the dispersive element and a rear focal point coincides with the center of the slit. Lens or first curved mirror,
The confocal optical system is constituted by at least a second and a third lens or a second and a third curved mirror. The spectrometer of claim 1, wherein
The dispersive element is a reflective diffraction grating,
The confocal optical system is composed of at least first and second two lenses or first and second curved mirrors,
The slit is disposed on the focal plane of these two lenses or two curved mirrors, which is between the first and second lenses or between the first and second curved mirrors,
Each of the light incident on the first lens or the first curved mirror from the deflection element and the light incident on the dispersion element from the second lens or the second curved mirror are each of the confocal optical system. A spectroscope characterized in that its position or angle is offset with respect to the optical axis. The spectrometer according to claim 3, wherein
The slit is provided in a partial region in the mirror,
The light from the deflection element is reflected by the mirror and enters the dispersion element,
A spectroscope characterized in that only light having a part of the wavelength of light dispersed by the dispersive element passes through the slit. The spectrometer of claim 1, wherein
The spectroscopic optical system is further arranged between the dispersive element and the slit such that a front focal point coincides with a dispersive surface of the dispersive element and a rear focal point coincides with the center of the slit. Lens or first curved mirror,
The confocal optical system is composed of at least second and third two lenses or second and third curved mirrors,
The light incident on the deflecting element is located between the second and third lenses or the second and third curved mirrors, and the light exit end is disposed on the focal plane of these two lenses or two curved mirrors. Emitted from the fiber,
The spectroscope characterized in that the position or angle of light incident on the deflection element from the second lens or second curved mirror is offset with respect to the optical axis of the confocal optical system. The spectrometer of claim 1, wherein
The confocal optical system includes a single lens or curved mirror, and a mirror that reflects the light reflected by the deflection element and passed through the lens or curved mirror in the direction of the lens or curved mirror and enters the dispersion element And consists of
The dispersive element is a reflective diffraction grating,
The deflection element and the dispersion element are arranged on one focal plane of the lens or the curved mirror,
The mirror and the slit are disposed on the other focal plane of the lens or curved mirror,
The spectroscope characterized in that light that passes through the lens or curved mirror and enters the deflection element is emitted from a fiber having a light exit end disposed on the other focal plane of the lens or curved mirror. The spectrometer according to claim 2, wherein
Of the two lenses or two curved mirrors constituting the confocal optical system, the third lens closer to the dispersive element than the focal length of the second lens or second curved mirror closer to the deflecting element. The focal length of this lens or the third curved mirror is long,
The spectroscope, wherein the deflecting element is a MEMS mirror. The spectrometer according to claim 2, wherein
Of the two lenses or two curved mirrors constituting the confocal optical system, the third lens closer to the dispersive element than the focal length of the second lens or second curved mirror closer to the deflecting element. The focal length of this lens or the third curved mirror is short,
The spectroscope, wherein the deflecting element is a liquid crystal or LCOS.

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