JP4556620B2 - Spectrometer - Google Patents

Description

  The present invention provides a spectroscopic device comprising: a plurality of reflective diffraction gratings; and a rotation mechanism that integrally rotates the plurality of diffraction gratings to position any one of the plurality of diffraction gratings at a spectroscopic position. Relates to the device.

  An example of a conventional spectroscopic device is shown in FIG.

  The spectroscopic device includes two reflection type diffraction gratings 11a and 11b, a rotation mechanism 12 that integrally rotates the two diffraction gratings 11a and 11b, a collimator mirror 15 that collimates light from the outside, and 2 And a condensing mirror 16 that condenses light from one of the diffraction gratings 11a and 11b.

  In general, a diffraction grating differs in diffraction efficiency for light in a certain wavelength range and diffraction efficiency for light in other wavelength ranges. Therefore, in order to perform spectroscopy with a high diffraction efficiency over a wide wavelength range, for example, by providing a diffraction grating 11a having a high diffraction efficiency in a short wavelength range and a diffraction grating 11b having a high diffraction efficiency in a long wavelength range, A rotation axis is provided behind the diffraction surface of each diffraction grating 11a, 11b so that each diffraction grating 11a, 11b can be switched and used. In such a spectroscopic device, in order to extract a desired wavelength range from the diffracted light, the angle of the diffraction grating with reference to the rotation axis is adjusted so that the desired wavelength light is emitted from the slit.

  In addition, as a spectroscopic device of the same type as this spectroscopic device, for example, there is a device in which the back surfaces of two reflective diffraction gratings are bonded to each other as described in Patent Document 1 below.

Japanese Patent Laid-Open No. 11-14457

  However, in the spectroscopic apparatus shown in FIG. 10, since the rotation axis is not on the diffraction surface of the diffraction grating, when the diffraction grating is rotated, not only the incident angle of light incident on the diffraction grating but also the position of the diffraction grating surface changes. There is a problem that the incident position and the incident angle on the surface that receives light from the spectroscopic device change. As described above, if the incident position and the incident angle on the surface that receives light from the spectroscopic device change, the illumination from the spectroscopic device changes when the used diffraction grating changes when trying to Keller illuminate a desired location. Inconveniences such as position movement occur.

  In addition, the spectroscopic device described in Patent Document 1 has a problem that the number of mounted diffraction gratings is limited to two, and three or more diffraction gratings cannot be used.

  The present invention has been made paying attention to such problems of the prior art, and can eliminate or minimize changes in the incident position and angle of light on the surface that receives light from the spectroscopic device. A spectroscopic device capable of mounting three or more diffraction gratings is also provided.

The spectroscopic device of the invention according to claim 1 for solving the above problem is
A plurality of reflection-type diffraction gratings, a rotation mechanism that rotates the plurality of diffraction gratings integrally, and positions one of the plurality of diffraction gratings at each spectroscopic position; and A light collecting optical system for collecting light from the diffraction grating, and a spectroscopic device comprising:
With respect to the light beam from one diffraction grating located at the spectroscopic position, there is no shift amount of the light flux from another diffraction grating located at the spectroscopic position by driving the rotation mechanism, and / or An optical path changing means for changing the optical path of the light from the condensing optical system is provided so that the directions of the light beams from other diffraction gratings are the same.

The spectroscopic device of the invention according to claim 2 is:
The spectroscopic device according to claim 1,
The optical path changing means includes a mirror disposed at or near the imaging position by the condensing optical system, and a mirror rotation for rotating the mirror around a rotation axis parallel to a rotation axis of the plurality of diffraction gratings. And a mechanism.

The spectroscopic device of the invention according to claim 3 is:
The spectroscopic device according to claim 2,
The mirror is disposed at an image forming position by the condensing optical system, and the width of the spectroscopic direction of the mirror by the diffraction grating is a width capable of reflecting light within a target wavelength width.

The spectroscopic device of the invention according to claim 4 is:
The spectroscopic device according to claim 1,
The optical path changing means includes a secondary condensing optical system that condenses the light collected by the condensing optical system, a mirror disposed at an image forming position by the secondary condensing optical system, A mirror rotation mechanism for rotating the mirror around a rotation axis parallel to the rotation axis of the diffraction grating.

The spectroscopic device of the invention according to claim 5 is:
In the spectroscopic device according to any one of claims 2 to 4,
The optical path changing means includes control means for driving the mirror rotating mechanism in conjunction with driving of the rotating mechanisms of a plurality of the diffraction gratings.

The spectroscopic device of the invention according to claim 6 is:
The spectroscopic device according to claim 1,
The optical path changing means includes a collimating optical system for collimating light from the condensing optical system, a transparent parallel plate on which an incident surface and an output surface are parallel to each other, and light collimated by the collimating optical system is incident thereon, It is characterized by having.

The spectroscopic device of the invention according to claim 7 is:
The spectroscopic device according to claim 1,
The optical path changing means includes a prism on which light from the condensing optical system is incident.

  According to the present invention, since the optical path changing means for changing the optical path of the light from the condensing optical system is provided, the wavelength of the diffraction grating with the rotation axis deviating from the diffractive surface can be reduced even though the configuration is simple. It is possible to eliminate or minimize the change in the incident position and incident angle of light on the surface that receives light from the spectroscopic device at the time of switching. Three or more diffraction gratings can also be mounted.

  Hereinafter, various embodiments of a spectroscopic device according to the present invention will be described with reference to the drawings.

  First, a spectroscopic device as a first embodiment according to the present invention will be described with reference to FIG.

  The spectroscopic device of the present embodiment includes a spectroscopic device body 10 and an optical path changing mechanism 20 that changes the optical path of light emitted from the spectroscopic device body 10.

  The spectroscopic device body 10 includes two reflection type diffraction gratings 11a and 11b, a rotation mechanism 12 that integrally rotates the two diffraction gratings 11a and 11b, a collimator mirror 15 that collimates light from the outside, A condensing mirror 16 that condenses light from one of the two diffraction gratings 11a and 11b and a casing 17 covering these are provided.

  Of the two diffraction gratings 11a and 11b, the first diffraction grating 11a has, for example, good diffraction efficiency for light in the long wavelength range, and the second diffraction grating 11b has, for example, light for the short wavelength range. On the other hand, the diffraction efficiency is good.

  The rotation mechanism 12 includes a rotation shaft 13 provided at an intermediate point between the diffraction surfaces of the diffraction gratings 11a and 11b, and a drive source 14 that rotates the two diffraction gratings 11a and 11b around the rotation shaft 13. Have.

  The casing 17 is formed with an entrance slit 18 through which light from outside enters and an exit slit 19 through which light exits. The collimating mirror 15 is arranged at a position where the light from the incident slit 18 can be reflected in the direction of a diffraction grating located at a later-described spectroscopic position, and the condensing mirror 16 is diffracted at the spectroscopic position. It is arranged at a position where light from the grating can be reflected in the direction of the exit slit 19.

  The optical path changing mechanism 20 includes a plane mirror 21 disposed in the vicinity of the exit slit 19, a mirror rotating mechanism 22 that rotates the mirror, and a controller 25 that controls the operation of the mirror rotating mechanism 22. . The mirror rotating mechanism 22 includes a rotating shaft 23 parallel to the rotating shaft 13 of the diffraction grating rotating mechanism 12 and a drive source 24 that rotates the flat mirror 21 around the rotating shaft 23. The controller 25 controls the driving of the mirror rotating mechanism 22 and also controls the driving of the diffraction grating rotating mechanism 12.

  Next, the operation of the spectroscopic device of this embodiment will be described.

  First, the operation at the time of splitting light of wavelength α1 from white light L using the first diffraction grating 11a will be described.

  First, the controller 25 is instructed to drive the rotating mechanism 12 to adjust the angle of the first diffraction grating 11a to the position where the light having the wavelength α1 can be dispersed.

  In this state, when white light L is incident from the entrance slit 18, the white light L is collimated by the collimator mirror 15, and then is reflected in each wavelength region by the first diffraction grating 11 a located at the spectroscopic position. Is split into the light. The light of each wavelength region dispersed by the first diffraction grating 11 a is reflected by the condenser mirror 16 and faces the exit slit 19 to form a spectrum image in the vicinity of the exit slit 19. Of this spectrum image, only light in a certain wavelength region centered on the wavelength α1 is emitted from the exit slit 19. The spectrally dispersible position of the wavelength α1 related to the first diffraction grating 11a described above is a position where the white light L from the collimating mirror 15 can be dispersed, and among the light in each wavelength region obtained as a result of the spectroscopy, This is a position where only light in a certain wavelength region centered on the wavelength α1 can be emitted from the emission slit 19.

  The light in the constant wavelength region centered on the wavelength α1 emitted from the exit slit 19 is reflected by the flat mirror 21 disposed in the vicinity of the exit slit 19 and travels to the target position.

  Next, an operation when the light having the wavelength α2 is split from the white light L using the same diffraction grating 11a will be described.

  First, an instruction is given to the controller 25 to drive the rotating mechanism 12, and the angle of the first diffraction grating 11a is adjusted to the position where the light having the wavelength α2 can be dispersed. When the rotating mechanism 12 is driven, the mirror rotating mechanism 22 is also driven in conjunction with this driving. This driving will be described later.

  In the above state, as described above, when the white light L is incident from the incident slit 18, the white light L is collimated by the collimator mirror 15. Then, the collimated white light L is split into light in each wavelength region by the first diffraction grating 11a. The light in each wavelength region dispersed by the first diffraction grating 11 a is reflected by the condensing mirror 16 and faces the exit slit 19 to form a spectral image in the vicinity of the exit slit 19. Of this spectrum image, only light in a certain wavelength region centered on the wavelength α2 is emitted from the emission slit 19. Note that the spectrally dispersible position of the wavelength α2 with respect to the first diffraction grating 11a described above is a position where the white light L from the collimating mirror 15 can be dispersed, and among the light in each wavelength region obtained as a result of the spectroscopy, This is a position where only light in a certain wavelength region centered on the wavelength α 2 can be emitted from the emission slit 19. The position at which the wavelength α2 can be dispersed with respect to the first diffraction grating 11a is different from the position at which the wavelength α1 can be dispersed with respect to the first diffraction grating 11a. That is, the position and angle of the diffraction surface of the first diffraction grating 11a when the light having the wavelength α1 is separated from that of the first diffraction grating 11a when the light having the wavelength α2 are separated are different from each other.

  By the way, although the light of wavelength α1 and the light of wavelength α2 are both emitted from the exit slit 19, the first diffraction grating 11a that splits the wavelength α1 and the first diffraction grating 11a that splits the wavelength α2 As described above, since the position and angle of the diffraction surface are different, the light beam with the wavelength α2 is located in the optical path from the first diffraction grating 11a to the exit slip 19 with respect to the light beam with the wavelength α1. In addition to the quantitative shift, the direction is also different.

  Therefore, in the present embodiment, as described above, when the diffraction grating rotating mechanism 12 is driven, the mirror rotating mechanism 22 is also driven, the plane mirror 21 is rotated by a predetermined angle, and the wavelength α1 emitted from the exit slit 19 is changed. Similarly, the direction of the light beam having the wavelength α2 emitted from the exit slit 19 is substantially matched to the light beam. In this example, since the plane mirror 21 is disposed near the exit slit 19, the shift amount of the light beam having the wavelength α2 with respect to the light beam having the wavelength α1 can be reduced. This is because the light of wavelength α1 and the light of wavelength α2 from the first diffraction grating 11a form an image at the position of the exit slit 19, that is, the image formation position by the condensing mirror 16. If the shift amount of the light beam having the wavelength α2 with respect to the light beam with the wavelength α1 is approximately 0 and the plane mirror 21 is brought close to the imaging position, the shift amount of the light beam with the wavelength α2 with respect to the light beam with the wavelength α1 is small. This is because the direction of the light beam having the wavelength α1 can be matched with the direction of the light beam having the wavelength α2.

  As described above, in this embodiment, the light path changing mechanism 20 can minimize the light incident position and angle on the surface that receives the light emitted from the spectroscopic device. In the above description, the case where the angle of the first diffraction grating 11a is changed has been described. However, even when the first diffraction grating 11a is switched to the second diffraction grating 11b, the optical path changing mechanism 20 emits light. It goes without saying that the same effect as described above can be obtained by changing the optical path of the light flux from the slit 19.

  In the present embodiment, since the optical path changing mechanism 20 is provided at the subsequent stage of the condenser mirror 16, three or more diffraction gratings can be provided at the preceding stage without any problem.

  Next, a modification of the spectroscopic device according to the first embodiment will be described with reference to FIG.

  In this modification, the plane mirror 21 a of the optical path changing mechanism 20 a is arranged at the image forming position of the condenser mirror 16. For this reason, in the first embodiment, the position of the exit slit 19 is the imaging position of the condenser mirror 16, but in this modification, the plane mirror 21a is disposed at the imaging position of the condenser mirror 16. Therefore, the exit opening 19a corresponding to the exit slit 19 of the first embodiment is located closer to the condensing mirror 16 than the exit slit 19, and the opening width is larger. For this reason, this emission opening 19a does not function sufficiently as a slit. Therefore, in this modification, the width of the plane mirror 21a is made narrower than that of the first embodiment, and the plane mirror 21a has a slit function. Specifically, the width of the diffraction grating in the plane mirror 21a in the spectral direction is a width that can reflect light within the target wavelength width. The spectral direction of the diffraction grating is a direction parallel to the diffraction surface and perpendicular to the direction in which the grooves of the diffraction grating extend.

  As described above, in this modification, the planar mirror 21a that aligns the direction of the light beam with the wavelength α2 with respect to the light beam with the wavelength α1 is disposed at the imaging position where the shift amount of the light beam with the wavelength α2 with respect to the light beam with the wavelength α1 is almost zero. Therefore, the direction of the light beam having the wavelength α2 can be matched to the light beam having the wavelength α1, and the shift amount of the light beam having the wavelength α2 with respect to the light beam having the wavelength α1 can be minimized.

  Next, a spectroscopic device as a second embodiment according to the present invention will be described with reference to FIG.

  The spectroscopic device of the present embodiment includes the same spectroscopic main body 10 as in the first embodiment, and an optical path changing mechanism 20b that changes the optical path of the light emitted from the spectroscopic main body 10.

  The optical path changing mechanism 20b includes a condensing lens 26 that re-images the light imaged by the condensing mirror 16 of the spectroscopic device body 10, and a flat mirror 21 disposed at the image forming position of the condensing lens 26. A mirror rotating mechanism 22 that rotates the mirror rotating mechanism 22 and a controller 25 that controls the operation of the mirror rotating mechanism 22 are provided.

  The plane mirror 21 of the optical path changing mechanism 20b is an image forming position of the condensing lens 26, that is, a position optically conjugate with the plane mirror 21a of the above-described modification, in other words, a light beam having a wavelength α2 with respect to a light beam having a wavelength α1. Is disposed at the image forming position where the shift amount is approximately 0, the direction of the light beam having the wavelength α2 can be matched to the light beam having the wavelength α1, and the wavelength α1. The amount of shift of the light beam having the wavelength α2 with respect to the light beam can be minimized.

  In this embodiment, unlike the above-described modification, the exit opening 19 of the casing 17 functions as an exit slit in the same manner as the conventional spectroscopic device shown in FIG. In addition, by adding the optical path changing mechanism 20b of the present embodiment, the same effects as those of the present embodiment can be easily obtained. That is, when the conventional spectroscopic device is improved, by adopting the configuration shown in the present embodiment, it is possible to easily align the directions of the light beams having the wavelengths α1 and α2.

  Next, a spectroscopic device as a third embodiment according to the present invention will be described with reference to FIGS.

  As shown in FIG. 4, the spectroscopic device of the present embodiment includes the same spectroscopic device body 10 as in the first embodiment, and an optical path changing mechanism 20 c that changes the optical path of light emitted from the spectroscopic device body 10. I have.

  The optical path changing mechanism 20 c includes a collimating lens 28 that collimates the light imaged by the condenser mirror 16 of the spectroscopic device body 10 and a transparent parallel plate 29 on which the light collimated by the collimating lens 28 enters. .

  In the transparent parallel flat plate 29 of the optical path changing mechanism 20c, an incident surface on which light collimated by the collimating lens 28 is incident and an output surface from which light incident from the incident surface is emitted are parallel to each other. The normal lines of the entrance surface and the exit surface that are parallel to each other of the transparent parallel plate 29 are inclined with respect to the optical axis of the collimator lens 28.

  The light of wavelength α1 emitted from the exit slit 19 of the spectroscopic device body 10 and the light of wavelength α2 emitted from the exit slit 19 are collimated by the collimator lens 28 to become parallel light beams. Lights having wavelengths α1 and α2 that are parallel to each other enter the incident surface of the transparent parallel plate 29 and exit from the exit surface. At this time, although the light beams having the wavelengths α1 and α2 are refracted at the entrance surface and the exit surface of the transparent parallel plate 29, the incident angle of the light with respect to the entrance surface and the exit angle of the light with respect to the exit surface are the same. Therefore, the incident light and the outgoing light are parallel. Therefore, the light having the wavelength α1 and the light having the wavelength α2 that are parallel to each other are parallel to each other even after being emitted from the transparent parallel plate 29. For this reason, if the light of the wavelengths α1 and α2 can be emitted from the same position, the shift amount of the light of the wavelength α2 with respect to the light of the wavelength α1 is set to 0 while aligning the directions of the light of the wavelengths α1 and α2. Can do. That is, in the present embodiment, it is utilized that the refraction angle of light incident on the parallel plate differs according to the wavelength of light incident on the parallel plate.

  For example, as shown in FIG. 5, the distance between the incident point O1 of the light having the wavelength α1 and the incident point O2 of the light having the wavelength α2 on the incident surface 29i, that is, the shift amount of the light having the wavelength α2 with respect to the light having the wavelength α1 is δ. The thicknesses of the transparent parallel plates 29 when the light refracting angles of the wavelengths α1 and α2 are θ1 and θ2, respectively, and the light of the wavelength α1 and the light of the wavelength α2 are emitted from the same position O3 on the emission surface 29o are d and Then, the relationship expressed by the following (Equation 1) is established.

d = δ / (tan θ2−tan θ1) (Equation 1)
Therefore, when the transparent parallel flat plate 29 is formed of materials having the refraction angles of the wavelengths α1 and α2 with θ1 and θ2, respectively, when the shift amount of the light with the wavelength α2 with respect to the light with the wavelength α1 is δ, (Equation 1) When the transparent parallel flat plate 29 having the thickness d shown in FIG. 4 is formed, the light with the wavelength α1 and the light with the wavelength α2 can be emitted from the same position O3.

  Further, the inclination of the transparent parallel plate 29 with respect to the optical axis of the collimating lens 28 is obtained as follows. In general, it is known that the refractive index when light enters an object increases as the wavelength of light decreases, and conversely decreases as the wavelength increases. The relationship between the wavelength and the refractive index does not completely satisfy linearity, but it can be regarded as being substantially linear as long as it is limited to a predetermined wavelength region that can be dispersed by the diffraction grating. Therefore, the transparent parallel flat plate 29 has a shift amount due to a predetermined wavelength difference at the incident surface of the transparent parallel flat plate 29 so as to be a product of the difference between the tangents of the refraction angles at the respective wavelengths and the thickness d of the transparent parallel flat plate 29. The 29 collimating lenses 28 are inclined with respect to the optical axis.

  In the present embodiment, the thickness of the transparent parallel plate 29 is set to a thickness d that can cancel out the shift amount of the light with the wavelength α2 with respect to the light with the wavelength α1 as described above. The shift amount of the light with the wavelength α2 with respect to the light with the wavelength α1 is set to zero.

  As described above, in the present embodiment, the amount of shift of the light with the wavelength α2 with respect to the light with the wavelength α1 can be made zero while aligning the direction of the light with the arbitrary wavelengths α1 and α2 by the transparent parallel plate 29. The drive mechanism and its control mechanism are unnecessary, the structure is simplified, and the manufacturing cost can be reduced.

  Next, a spectroscopic device as a fourth embodiment according to the present invention will be described with reference to FIGS.

  As shown in FIG. 6, the spectroscopic device of this embodiment includes the same spectroscopic device body 10 as that of the first embodiment, and a prism 20d as an optical path changing mechanism that changes the optical path of light emitted from the spectroscopic device body 10. And.

  It is the figure which expanded the diffraction grating vicinity (= vicinity of the conventional diffraction grating shown in FIG. 10) of this embodiment. In general, there are several sizes of commercially available diffraction gratings, but those having an effective area of 50 mm square are relatively often used. Therefore, here, the diffraction grating 11 of 50 mm square is taken as an example. In this spectroscopic device, for example, it is inclined by 17 ° with respect to the central axis C of the spectroscopic device (a line dividing the spectroscopic main body 10 into the incident side and the exit side, a line between the entrance slit 18 and the exit slit 19). It is assumed that light enters the diffraction grating 11 at an angle and the diffracted light also exits at an angle of 17 ° with respect to the central axis C. If the angle between the normal line N of the diffraction grating surface at this time and the central axis C of the spectroscopic device is θ, and the wavelength output from the exit slit is λ, the value of θ is given by the following equation (2).

  From this number 2, if the number of grooves N of the diffraction grating is 1200 / mm, and the wavelength λ is 400 nm, θ is 14.8 °. When the wavelength λ is 800 nm, θ is 30 °. Therefore, there is an angular difference of 15.2 ° between the angle of the diffraction grating when extracting 400 nm wavelength light from the exit slit 19 and the angle of the diffraction surface when extracting 800 nm wavelength light.

In the case of the two-sheet switching method as in this embodiment and the prior art in FIG. 10, as shown in FIG. 8, the angle of the diffraction grating is adjusted for switching the diffraction grating and selecting the wavelength between the two diffraction gratings. There is an axis A. In this embodiment, considering the size (50 mm square) of the diffraction grating, the distance from the rotation axis A to the diffraction surface of the diffraction grating is set to 16.7 mm. In FIG. 8, N ₄₀₀ is a normal line of the diffraction grating 11 when emitting light having a wavelength of ₄₀₀ nm, and N ₈₀₀ is a normal line of the diffraction grating 11 when emitting light having a wavelength of ₈₀₀ nm.

  The diffraction surface is rotated by 15.2 ° when emitting 400 nm wavelength light from the exit slit (shown by the solid line in the figure) and when emitting 800 nm wavelength light from the exit slit (shown by the dashed line in the figure). Since the distance from the diffraction surface to the rotation axis is 16.7 mm, the chief ray H of the 800 nm wavelength light is shifted by 4.39 mm with respect to the chief ray G of the 400 nm wavelength light. That is, the chief ray H of the wavelength light of 800 nm is shifted by about 10% of the effective area of the diffraction grating 11.

  At this time, the light emitted from the spectroscopic device body 10 is considered. Since the light exiting the diffraction grating 11 is collected by the condenser mirror 16, the shift of the principal ray exiting the diffraction grating 11 is reversed by the condenser mirror, and then the principal ray is inclined. The F number of a general spectroscopic device is often about 5, and the F number of the spectroscopic main body of this embodiment is also 5. In this case, since the shift amount on the diffraction grating is about 10% of the effective area as described above, the output chief ray is only 1.1 ° which is 10% of the opening angle of 11.4 ° when the F number is 5. Will tilt.

  By the way, in this embodiment, the prism 20d is provided after the exit slit 19 of the spectroscope body 10. The prism 20d has an apex angle of about 35 °, and light having a wavelength of 400 nm out of the light emitted from the exit slit 19 enters the prism 20d at an incident angle of 30 °.

  As shown in FIG. 9 (a), the angle between the 400 nm chief ray and the 800 nm chief ray after the prism exits when 400 nm and 800 nm wavelength light is incident at the same incident angle (30 °) is calculated. Then, it becomes about 0.94 °. Here, calculation is performed assuming that LAFN7 manufactured by Schott is used for the glass of the prism 20d, the refractive index of the wavelength light of 400 nm is 1.789888, and the refractive index of the wavelength light of 800 nm is 1.734781.

  Therefore, the light having a wavelength of 400 nm and the light having a wavelength of 800 nm incident on the prism 20d with an incident angle difference of 0.94 ° are emitted from the prism d with the same emission angle. Therefore, as shown in FIG. 9B, the 400 nm wavelength light λ2 emitted from the exit slit 19 of the spectroscope main body 10 and incident on the prism 20d at an incident angle of about 30 °, and the main components of the 400 nm wavelength light λ2 The 800 nm wavelength light λ1 having an incident angle difference of about 1.1 ° with respect to the light beam is emitted from the prism 20d in a state where the emission angles are substantially uniform (with an angle difference of only 0.16 °).

  As described above, in this embodiment, the shift of the principal ray of the light beam emitted from the diffraction grating 11 converted into the inclination of the optical axis by the condensing optical system is the prism 22d disposed on the rear side of the condensing optical system. Therefore, the shift of the incident position and the incident angle due to the difference in wavelength can be minimized. In the present embodiment, the prism 20d is disposed behind the exit slit 19, that is, behind the image forming position of the collector mirror 19. However, of course, the prism 20d may be disposed in front of the image forming position. As long as the injection angle can be made uniform, it may be arranged at any position. In addition, the prism is arranged at the optimum position so as to minimize the shift amount of the light beams having different wavelengths, depending on the dispersion characteristics of the prism, whether on the front side or the rear side of the imaging position. It is preferable.

  As described above, according to the present embodiment, even in a spectroscopic device in which the rotation axis is not on the diffraction grating surface with a very simple configuration in which a prism is arranged on the rear side of the condensing optical system, Each wavelength light incident angle, incident position, or incident angle and incident position can be aligned.

  Each of the above embodiments and modifications includes two diffraction gratings 11a and 11b. However, as described in the first embodiment, three or more diffraction gratings are mounted. Needless to say, you can.

It is explanatory drawing which shows the structure of a spectroscopic apparatus as 1st Embodiment concerning this invention. It is explanatory drawing which shows the structure of the spectroscopy apparatus as a modification of 1st Embodiment based on this invention. It is explanatory drawing which shows the structure of the spectrometer as 2nd Embodiment which concerns on this invention. It is explanatory drawing which shows the structure of the spectrometer as 3rd Embodiment concerning this invention. It is explanatory drawing for demonstrating the setting of the thickness of the transparent parallel flat plate in 3rd Embodiment. It is explanatory drawing which shows the structure of the spectrometer as 4th Embodiment concerning this invention. It is explanatory drawing which shows the diffraction grating vicinity in a prior art and 4th Embodiment. It is explanatory drawing which shows the shift of the light from which a wavelength differs in a prior art and 4th Embodiment. In 4th Embodiment which concerns on this invention, it is explanatory drawing which shows the principle which the emission direction of the light of each wavelength aligns. It is explanatory drawing which shows the structure of the conventional spectroscopy apparatus.

Explanation of symbols

10: Spectrometer main body 11a, 11b: Diffraction grating 12: Rotating mechanism 15: Collimating mirror 16: Condensing mirror 20, 20a, 20b, 20c: Optical path changing mechanism 20d: Prism 21, 21a: Plane mirror 22, 22a: Mirror rotating Mechanism 25: Controller 26: Condensing lens 28: Collimating lens 29: Transparent parallel plate

Claims (7)

A plurality of reflection-type diffraction gratings, a rotation mechanism that rotates the plurality of diffraction gratings integrally, and positions one of the plurality of diffraction gratings at each spectroscopic position; and A condensing optical system that condenses the light from the diffraction grating,
With respect to the light beam from one diffraction grating located at the spectroscopic position, the shift amount of the light beam from another diffraction grating located at the spectroscopic position is eliminated by driving the rotation mechanism, and / or An optical path changing means for changing the optical path of the light from the condensing optical system so that the directions of the light beams from the other diffraction gratings are the same;
A spectroscopic device characterized by that. The spectroscopic device according to claim 1,
The optical path changing means includes a mirror disposed at or near the imaging position by the condensing optical system, and a mirror rotation for rotating the mirror around a rotation axis parallel to a rotation axis of the plurality of diffraction gratings. Having a mechanism,
A spectroscopic device characterized by that. The spectroscopic device according to claim 2,
The mirror is disposed at an image forming position by the condensing optical system, and the width of the spectroscopic direction of the mirror by the diffraction grating is a width capable of reflecting light within a target wavelength width.
A spectroscopic device characterized by that. The spectroscopic device according to claim 1,
The optical path changing means includes a secondary condensing optical system that condenses the light collected by the condensing optical system, a mirror disposed at an image forming position by the secondary condensing optical system, A mirror rotation mechanism for rotating the mirror around a rotation axis parallel to the rotation axis of the diffraction grating,
A spectroscopic device characterized by that. In the spectroscopic device according to any one of claims 2 to 4,
The optical path changing means includes control means for driving the mirror rotating mechanism in conjunction with driving of the rotating mechanisms of the plurality of diffraction gratings.
A spectroscopic device characterized by that. The spectroscopic device according to claim 1,
The optical path changing means includes a collimating optical system for collimating light from the condensing optical system, a transparent parallel plate on which an incident surface and an output surface are parallel to each other, and light collimated by the collimating optical system is incident thereon, Having
A spectroscopic device characterized by that. The spectroscopic device according to claim 1,
The optical path changing means has a prism on which light from the condensing optical system is incident.
A spectroscopic device characterized by that.

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