JP6743500B2 - Spectroscope and incident light limiting member used therein - Google Patents

Description

The present invention relates to a spectroscope that diffracts light that has passed through an incident slit with a diffraction grating to disperse the light and an incident light limiting member used for the spectroscope.

As an example of a spectroscope, a monochromator is known in which light incident from an entrance slit is dispersed by a diffraction grating and only light having a specific wavelength is emitted from an exit slit (for example, refer to Patent Document 1 below). In this type of spectroscope, for example, a diffraction grating is provided in the housing, and an entrance portion (incident port) having an entrance slit is formed on the wall surface of the housing, and an exit portion (emission port) having an exit slit is formed. Is provided.

The light from the light source is condensed via an optical system and enters the housing through an entrance slit formed of a minute opening. The light that has entered the housing reaches the diffraction grating while spreading, and is diffracted in the effective area (grating surface) of the diffraction grating to be split into light of each wavelength. The diffraction grating is rotatably provided, and light having a specific wavelength corresponding to the rotation position is collected and emitted to the outside of the housing through the emission slit.

In a highly versatile monochromator, the user arbitrarily selects the configuration of the optical system that guides the light from the light source. There are various variations of the above-mentioned optical system, such as a configuration in which light from a light source is condensed using a condenser lens and a configuration in which light from the light source is guided using one or a plurality of optical fibers.

JP, 2008-185525, A

When the optical system that guides the light from the light source has various variations as described above, the brightness of the incident light flux changes depending on the configuration of the optical system. That is, when the angle range of the incident light flux is large, the F value, which is an index of brightness, decreases and the brightness of the incident light flux increases. On the other hand, when the angle range of the incident light flux is small, the F value increases and the brightness of the incident light flux decreases.

8A and 8B are schematic cross-sectional views for explaining the angular range θ2 of the incident light flux. The light from the light source enters the housing 102 through the entrance slit 101 and is diffracted by the effective area 131 of the diffraction grating 103 provided in the housing 102.

As shown in FIG. 8A, when the F value is small and the angle range θ2 of the incident light flux is large, light may be incident on the entire effective area 131 of the diffraction grating 103. On the other hand, as shown in FIG. 8B, when the F value is large and the angle range θ2 of the incident light flux is small, the light may be incident only on a part of the effective region 131 of the diffraction grating 103.

If the F value is small, the sensitivity is improved, while if the F value is large, the resolution is improved. Therefore, the user can arbitrarily set the angle range θ2 of the incident light flux by adjusting the optical system (the condensing lens or the like) that guides the light from the light source to the incident slit 101 according to the desired sensitivity or resolution. You can

However, adjustment of the optical system as described above is not easy, and light may enter beyond the effective region 131 of the diffraction grating 103 as shown in FIG. 8A. In FIG. 8A, light that does not enter the effective region 131 of the diffraction grating 103 is shown by hatching. In this case, the light that does not enter the effective area 131 becomes a stray light source, which may adversely affect the measurement result.

Further, since it is complicated to set the angle range θ2 of the incident light flux every time the configuration of the optical system is changed, some users may use the monochromator without performing such work. .. Even in such a case, as shown in FIG. 8A, light may enter beyond the effective region 131 of the diffraction grating 103.

As described above, a versatile monochromator has a problem that stray light is likely to occur. In order to solve such a problem, measures are taken to reduce stray light by, for example, painting the inner surface of the housing black or attaching a member having a low reflectance to the inner surface of the housing. .. There is also known a method in which a black mask portion is provided at the edge portion of the diffraction grating to prevent light from scattering at the edge portion and reduce stray light.

However, the conventional method for reducing stray light as described above does not prevent the light exceeding the effective region 131 of the diffraction grating 103 from entering the housing itself. That is, since the stray light source is not completely blocked and stray light cannot be completely prevented from being generated in the housing, a configuration that can more effectively reduce stray light has been desired.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a spectroscope capable of reducing stray light more effectively and an incident light limiting member used for the spectroscope.

A spectroscope according to the present invention includes an entrance section, a diffraction grating, a mask section, and a trap section. An entrance slit through which the light from the light source passes is formed in the entrance part. The diffraction grating diffracts the light that has passed through the entrance slit in an effective area to disperse the light. The mask unit is provided between the incident unit and the diffraction grating, and reflects and shields at least a part of light that does not enter the effective region, of the light that has passed through the incident slit. A trap space for attenuating the light reflected by the mask portion is formed in the trap portion.

With such a configuration, at least a part of the light that does not enter the effective region of the diffraction grating is shielded by being reflected by the mask portion provided between the incident portion and the diffraction grating. Further, the light reflected by the mask portion is attenuated in the trap space. Thus, the light shielded by the mask portion does not reach the diffraction grating side and does not serve as a stray light source, so that stray light can be reduced more effectively.

The diffraction grating may be held rotatably about a rotation axis. In this case, it is preferable that at least the mask portion reflects and shields light that does not enter the effective region in a state where the diffraction grating is rotated at a rotation position where the amount of light incident on the effective region is maximum.

With such a configuration, the light that does not enter the effective region regardless of the rotation position of the diffraction grating is shielded by being reflected by the mask portion. As a result, unnecessary light can be reliably blocked, and stray light can be reduced more effectively.

The mask portion may be detachably attached to the trap portion.

According to such a configuration, the mask unit can be attached to the trap unit as necessary, so that the spectroscope having the configuration of the present invention can be provided only to a user who needs it. Further, for example, in the case where the trap section is provided with the incident section, the positional relationship between the incident section, the trap section, and the mask section does not shift, so that the stray light source can be accurately blocked and the position adjustment can be performed. It is possible to reduce the trouble of performing.

The mask part and the trap part may be integrally formed.

With such a configuration, the positional relationship between the mask portion and the trap portion does not shift, so that the stray light source can be accurately blocked. Further, for example, in the case where the trap section is provided with the incident section, the positional relationship with the incident section does not shift, so that the stray light source can be blocked more accurately and the time and effort for position adjustment can be reduced. Can be reduced.

The mask portion may be provided with a low reflectance member that reflects light while attenuating the light.

With such a configuration, when at least a part of the light that does not enter the effective area of the diffraction grating is reflected by the mask portion provided between the incident portion and the diffraction grating, the low reflection provided in the mask portion The reflected light is attenuated and reflected, and the reflected light is further attenuated in the trap space. Therefore, stray light can be reduced more effectively.

A low reflectance member that reflects light while attenuating the light may be provided on the inner surface of the trap space.

According to such a configuration, at least a part of the light that does not enter the effective area of the diffraction grating is reflected on the mask portion provided between the incident portion and the diffraction grating and then provided on the inner surface of the trap space. It is reflected while being attenuated by the low reflectance member. Therefore, stray light can be reduced more effectively.

An incident light restricting member according to the present invention is an incident light restricting member for restricting light from a light source that enters a spectroscope having a diffraction grating, and includes an incident portion, a mask portion, and a trap portion. .. An entrance slit through which the light from the light source passes is formed in the entrance part. The mask unit is provided between the incident unit and the diffraction grating, and reflects and shields at least a part of the light that has passed through the incident slit and does not enter the effective region of the diffraction grating. A trap space for attenuating the light reflected by the mask portion is formed in the trap portion.

According to the present invention, the light shielded by the mask portion does not reach the diffraction grating side and does not serve as a stray light source, so stray light can be reduced more effectively.

It is a schematic sectional drawing which showed the structural example of the spectrometer which concerns on one Embodiment of this invention. It is a schematic sectional drawing which showed the structural example of the incident light limiting member. It is a schematic sectional drawing which showed the 1st modification of the incident light limiting member. It is a schematic sectional drawing which showed the 2nd modification of the incident light limiting member. It is a schematic sectional drawing which showed the structural example of the spectrometer which concerns on another embodiment. It is a schematic sectional drawing which showed the structural example of the spectrometer which concerns on another embodiment. It is a schematic sectional drawing which showed the modification of the incident light limiting member in the spectroscope of FIG. FIG. 4 is a schematic cross-sectional view for explaining an angle range of an incident light beam, showing a case where the angle range of the incident light beam is large. FIG. 6 is a schematic cross-sectional view for explaining an angle range of an incident light beam, showing a case where the angle range of the incident light beam is small.

FIG. 1 is a schematic sectional view showing a configuration example of a spectroscope 1 according to an embodiment of the present invention. The spectroscope 1 is a monochromator for separating the light from the light source 2, and the light from the light source 2 is condensed by the condenser lens 3 and enters the spectroscope 1. The condenser lens 3 constitutes an optical system for guiding the light from the light source 2 to the spectroscope 1, and the user can arbitrarily select the configuration of the optical system. That is, the spectroscope 1 according to the present embodiment has high versatility, and the type of the condenser lens 3 can be changed or an optical system other than the condenser lens 3 can be adopted.

The spectroscope 1 includes, for example, an incident light limiting member 4, a first reflecting mirror 5, a diffraction grating 6, a second reflecting mirror 7 and an outgoing light limiting member 8. The outer shape of the spectroscope 1 is partitioned by the housing 9, and the first reflecting mirror 5, the diffraction grating 6, and the second reflecting mirror 7 are provided in the housing 9, and the incident light limiting member 4 is provided on the wall surface of the housing 9. And the emitted light limiting member 8 is attached. The incident light limiting member 4 and the outgoing light limiting member 8 are preferably attachable to and detachable from the wall surface of the housing 9.

The incident light limiting member 4 is provided with an entrance slit 41 formed of, for example, a small hole, and only the light passing through the entrance slit 41 is directed to the housing 9 side. Thereby, the light from the light source 2 entering the spectroscope 1 can be restricted, and only the light entering the spectroscope 1 can be reflected by the first reflecting mirror 5 and guided to the diffraction grating 6.

The light that has passed through the entrance slit 41 reaches the diffraction grating 6 while spreading. However, since the first reflecting mirror 5 is composed of, for example, a collimating mirror, the light passing through the entrance slit 41 is collimated by the first reflecting mirror 5 and then guided to the diffraction grating 6. May be. The first reflecting mirror 5 may be omitted, and the light passing through the entrance slit 41 may be directly guided to the diffraction grating 6.

A concave grating surface is formed on the diffraction grating 6, and the grating surface constitutes an effective area 61 on which the light passing through the entrance slit 41 is incident. The light that has passed through the entrance slit 41 is diffracted in the effective area 61, and thus is split into light of each wavelength. Then, the separated light of a specific wavelength is reflected by the second reflecting mirror 7 and is emitted to the outside of the housing 9 via the emission light limiting member 8. The second reflecting mirror 7 is composed of, for example, a focus mirror, collects the light from the diffraction grating 6 and guides it to the outgoing light limiting member 8.

The diffraction grating 6 is held rotatably around a rotation axis 62. For example, as shown by the broken line in FIG. 1, by rotating the diffraction grating 6 about the rotation axis 62, light of a specific wavelength corresponding to the rotation position is condensed, and the housing is provided via the emission light limiting member 8. 9 can be emitted to the outside.

The emission light restricting member 8 is provided with an emission slit 81 formed of, for example, a small hole, and only the light passing through the emission slit 81 is emitted to the outside of the housing 9. Thereby, the emission of stray light generated in the spectroscope 1 can be limited, and only the light of the specific wavelength split by the diffraction grating 6 can be emitted from the emission slit 81.

FIG. 2 is a schematic cross-sectional view showing a configuration example of the incident light limiting member 4. In FIG. 2, the first reflecting mirror 5 is omitted to simplify the description. The incident light limiting member 4 includes, for example, a main body 42, an incident plate 43, a mask plate 44, and the like. The incident light limiting member 4 is attached to the wall surface of the housing 9 from the outside, for example.

The main body 42 is made of, for example, a tubular member, and has an inlet side opening 421 formed at one end and an outlet side opening 422 formed at the other end. The light that enters the incident light limiting member 4 from the light source 2 through the condenser lens 3 enters from the inlet side opening 421 along the axis L of the body 42, passes through the body 42, and exits from the outlet side opening 422. ..

The outlet side opening 422 has a larger diameter than the inlet side opening 421, and communicates with each other via a step surface 423. The step surface 423 is formed by, for example, a surface orthogonal to the light incident direction (axis L direction). However, the configuration is not limited to such a configuration, and the step surface 423 may be configured by a surface that extends in a direction intersecting the direction of the axis L, such as a conical surface.

The entrance plate 43 constitutes an entrance part in which the above-mentioned entrance slit 41 is formed. The entrance plate 43 is attached to one end surface of the main body 42 to cover a part of the inlet side opening 421. That is, the entrance plate 43 projects to a position facing a part of the entrance-side opening 421, and the light that has passed through the entrance slit 41 enters the main body 42 through the entrance-side opening 421.

The entrance plate 43 is attachable to and detachable from the main body 42. As described above, when the entrance plate 43 is removable from the main body 42, the entrance plate 43 can be positioned and attached by a positioning member (not shown) such as a pin provided on the main body 42. It is preferable that the structure be such that it can be achieved. However, the entrance plate 43 is not limited to the configuration that is attachable to and detachable from the main body 42, and may be fixed to the main body 42.

The mask plate 44 constitutes a mask portion in which the emission slit 45 is formed. The exit slit 45 is composed of an opening larger than the entrance slit 41. The mask plate 44 covers a part of the outlet side opening 422 by being attached to the other end surface of the main body 42. That is, the mask plate 44 projects to a position facing a part of the outlet-side opening 422, and only the light that has passed through the exit slit 45 enters the housing 9.

An opening 91 larger than the exit slit 45 is formed in the housing 9, and the incident light limiting member 4 is attached to the housing 9 so that the exit slit 45 faces the opening 91. The incident light limiting member 4 may be fixed to the housing 9 or may be detachable. When the incident light limiting member 4 is attachable to and detachable from the housing 9, the incident light limiting member 4 is positioned and attached by a positioning member such as a pin provided on the incident light limiting member 4 or the housing 9. It is preferable that the structure be such that

The mask plate 44 is provided between the entrance plate 43 and the diffraction grating 6, and can limit the light guided from the entrance slit 41 to the diffraction grating 6 side according to the shape and position of the exit slit 45. .. In the present embodiment, the shape and position of the exit slit 45 are set so that at least a part of the light that has not passed through the effective area 61 of the diffraction grating 6 among the light that has passed through the entrance slit 41 is shielded by the mask plate 44. It is set.

More specifically, as shown by hatching in FIG. 2, light in a range exceeding the angular range θ1 of the incident light flux that enters the effective area 61 of the diffraction grating 6 is wholly or partially shielded by the mask plate 44. As described above, the shapes and positions of the entrance slit 41, the exit slit 45, and the effective area 61 are set. The light shielded by the mask plate 44 remains in the main body 42 by being reflected by the mask plate 44.

The mask plate 44 is attachable to and detachable from the main body 42. As described above, when the mask plate 44 is removable from the main body 42, the mask plate 44 can be positioned and attached by a positioning member (not shown) such as a pin provided on the main body 42. It is preferable that the structure be such that it can be achieved. However, the mask plate 44 is not limited to being detachable from the main body 42 and may be fixed to the main body 42.

A trap space 424 is formed inside the main body 42 to attenuate the light reflected by the mask plate 44. The trap space 424 is, for example, a space between the outlet opening 422 and the step surface 423, and the light reflected by the mask plate 44 is reflected inside the trap space 424 (the inner surface of the main body 42, the step surface 423, etc.). It is attenuated by repeating. The main body 42 constitutes a trap portion in which a trap space 424 is formed.

The inner surface of the trap space 424, that is, the inner surface of the main body 42 and the reflective surfaces such as the surface of the mask plate 44 on the side of the trap space 424 are painted black, for example, to attenuate light. However, the structure for attenuating light is not limited to the structure in which the reflecting surface is painted in black, and may be a structure painted in another color, or a member having a low reflectance is used as the reflecting surface. Various other configurations such as a pasted configuration can be adopted.

As described above, in the present embodiment, at least a part of the light that does not enter the effective area 61 of the diffraction grating 6 is shielded by being reflected by the mask plate 44 provided between the entrance plate 43 and the diffraction grating 6. It Further, the light reflected by the mask plate 44 is attenuated by the trap space 424. As a result, the light shielded by the mask plate 44 does not reach the diffraction grating 6 side and does not serve as a stray light source, so stray light can be reduced more effectively.

Further, in the present embodiment, the mask plate 44 is attachable to and detachable from the main body 42. Therefore, by attaching the mask plate 44 to the main body 42 as necessary, the configuration of the present embodiment can be provided only to a necessary user. The equipped spectroscope 1 can be provided. Further, in the case where the incident plate 43 is attached to the main body 42 as in the present embodiment, the positional relationship between the incident plate 43, the main body 42, and the mask plate 44 does not shift, so that the stray light source is accurately blocked. In addition, it is possible to reduce the time and effort for adjusting the position.

As described above, the diffraction grating 6 can rotate around the rotation axis 62. Therefore, for example, the angle of the effective area 61 with respect to the light from the exit slit 45 differs between the case where the diffraction grating 6 is in the rotation position shown by the solid line in FIG. The amount of light incident on will change.

In the present embodiment, light that does not enter the effective area 61 at least when the diffraction grating 6 is in the rotational position shown by the solid line in FIG. 2, that is, the angular range θ1 of the incident light flux that enters the effective area 61 of the diffraction grating 6 It is set so that the light in the range exceeding (the light in the hatched portion in FIG. 2) is reflected by the mask plate 44 and shielded. In the state where the diffraction grating 6 is in the rotation position shown by the solid line in FIG. 2, the amount of light incident on the effective area 61 is the largest as compared with the other rotation positions shown by the broken line in FIG.

With this setting, light (light in the hatched portion in FIG. 2) that does not enter the effective area 61 regardless of the rotational position of the diffraction grating 6 is transmitted by the mask plate 44. It is shielded by being reflected. As a result, unnecessary light can be reliably blocked, and stray light can be reduced more effectively.

However, the mask plate 44 is not limited to the configuration that blocks only the light in the range exceeding the angular range θ1 of the incident light flux that enters the effective area 61 of the diffraction grating 6. That is, the mask plate 44 may be configured to block the light from the entrance slit 41 in a range narrower than the angle range θ1, or the light from the entrance slit 41 in a range wider than the angle range θ1. It may be configured to block the light.

In the above-described embodiment, the configuration in which the incident light limiting member 4 is attached to the wall surface of the housing 9 from the outside has been described. 4 may be attached. Further, at least one of the main body 42, the entrance plate 43, and the mask plate 44 may be provided separately.

FIG. 3 is a schematic sectional view showing a first modification of the incident light limiting member 4. In FIG. 3, as in the case of FIG. 2, the first reflecting mirror 5 is omitted to simplify the description. This example is different from the case of FIG. 2 only in that the mask plate 44 is separated from the main body 42, and other configurations are similar to the case of FIG. The same reference numerals are given and detailed description is omitted.

In this example, the main body 42 is attached to the housing 9 from the outside, and the mask plate 44 is attached to the housing 9 from the inside. That is, the outlet side opening 422 of the main body 42 and the emission slit 45 of the mask plate 44 communicate with each other through the opening 91 of the housing 9. The mask plate 44 covers a part of the opening 91 by protruding to a position facing a part of the opening 91 of the housing 9, and only the light passing through the exit slit 45 enters the housing 9. To do.

However, the structure is not limited to the mask plate 44 separated from the main body 42, and the incident plate 43 may be separated from the main body 42, or both the incident plate 43 and the mask plate 44 may be separated from the main body 42. A separate structure may be used. On the other hand, at least two of the main body 42, the entrance plate 43, and the mask plate 44 may be integrally formed by one member.

FIG. 4 is a schematic sectional view showing a second modification of the incident light limiting member 4. In FIG. 4, as in the case of FIG. 2, the first reflecting mirror 5 is omitted to simplify the description. In this example, the main body 42 and the mask plate 44 are integrally formed, and the shape of the trap space 424 is different from that of FIG. 2, and other configurations are similar to those of FIG. The same components are designated by the same reference numerals and detailed description thereof will be omitted.

In this example, the main body 42 and the mask plate 44 are integrally formed by one member. In the case of such a configuration, it is difficult to form the step surface 423 in the main body 42 as in the case of FIG. Therefore, in this example, the step surface 423 is not formed in the main body 42, and the trap space 424 is formed from the mask plate 44 to the inlet side opening 421.

In this case, the light reflected by the mask plate 44 is attenuated by being repeatedly reflected by the inner surface of the main body 42, the entrance plate 43, and the like. The inner surface of the trap space 424, that is, the inner surface of the main body 42 and the reflection surface such as the surface of the entrance plate 43 on the side of the trap space 424 is painted black, for example, to attenuate light. However, the structure for attenuating light is not limited to the structure in which the reflecting surface is painted in black, and may be a structure painted in another color, or a member having a low reflectance is used as the reflecting surface. Various other configurations such as a pasted configuration can be adopted.

In this way, in the case where the main body 42 and the mask plate 44 are integrally formed, the positional relationship between the main body 42 and the mask plate 44 does not shift, so that the stray light source can be accurately blocked. Further, if the entrance plate 43 is formed integrally with the main body 42, the positional relationship with the entrance plate 43 will not be displaced, so that the stray light source can be blocked more accurately and the position adjustment can be performed. It is possible to reduce the labor to do.

FIG. 5 is a schematic cross-sectional view showing a configuration example of the spectroscope 1 according to another embodiment. In this embodiment, the optical system for guiding the light from the light source 2 to the spectroscope 1 is configured by the optical fiber 10 instead of the condenser lens 3. Except for this point, the other configurations are the same as those of the above-described embodiment, and thus the same configurations are denoted by the same reference numerals and detailed description thereof will be omitted.

The incident light limiting member 4 is provided with a fiber attachment portion 46 for attaching the tip portion of the optical fiber 10. The fiber attachment portion 46 is attached to one end surface of the main body 42 to cover a part of the inlet side opening 421. A recess 461 extending along the axis L of the main body 42 is formed in the fiber attachment portion 46, and the tip of the optical fiber 10 is inserted and fixed in the recess 461.

The end surface of the optical fiber 10 is in contact with the bottom surface of the recess 461. An opening is formed on the bottom surface of the recess 461, and the opening constitutes the entrance slit 41. Thereby, the light from the front end surface of the optical fiber 10 passes through the entrance slit 41 and enters the main body 42 through the entrance side opening 421. However, the entrance slit 41 is not limited to the structure formed on the fiber attachment portion 46, and may be formed on a member (an entrance plate or the like) provided separately from the fiber attachment portion 46.

As described above, the optical system for guiding the light from the light source 2 to the spectroscope 1 is not limited to the condensing lens 3 and can be configured by using other various members such as the optical fiber 10. The number of optical fibers 10 is not limited to one, and a plurality of optical fibers 10 may be provided.

FIG. 6 is a schematic cross-sectional view showing a configuration example of the spectroscope 1 according to still another embodiment. In this embodiment, a low reflectance member 47 is provided on the incident light limiting member 4 shown in FIG. Except for this point, the other configuration is the same as the case of FIG. 2, and therefore the same configuration is denoted by the same reference numeral in the drawing, and detailed description thereof is omitted.

The low reflectance member 47 is provided on the mask plate 44. Specifically, the low reflectance member 47 is provided on the surface of the mask plate 44 on the trap space 424 side (the entrance slit 41 side). As shown in FIG. 6, the low reflectance member 47 preferably covers the mask plate 44 up to the peripheral edge of the exit slit 45.

The surface of the low reflectance member 47 on the trap space 424 side (on the entrance slit 41 side) is a low reflectance surface 471 that reflects light with low reflectance. As the low reflectance surface 471, various configurations are adopted, such as a configuration coated with a color having a low reflectance such as black, or a configuration in which a member made of a material having a low reflectance such as brushed paper is attached. be able to. The reflectance of the low reflectance surface 471 is preferably 2% or less, but practically more preferably 0.1 to 0.2%.

In the present embodiment, when at least a part of the light that does not enter the effective area 61 of the diffraction grating 6 is reflected by the mask plate 44 provided between the incident plate 43 and the diffraction grating 6, it is provided on the mask plate 44. The low-reflectance member 47 attenuates the reflected light, and the reflected light is further attenuated in the trap space 424. Therefore, stray light can be reduced more effectively.

In the example of FIG. 6, the configuration in which the mask plate 44 is attached to the main body 42 is shown, but the configuration is not limited to this, and the incident light limiting member 4 having another configuration as illustrated in FIGS. 3 to 5. In the above, the mask plate 44 may be provided with the low reflectance member 47.

FIG. 7 is a schematic sectional view showing a modification of the incident light limiting member 4 in the spectroscope of FIG. This example is different from the example of FIG. 6 only in that the low-reflectance member 47 is provided on the inner surface of the trap space 424, and other configurations are similar to the case of FIG. The same reference numerals are given to the drawings, and detailed description will be omitted.

The low reflectance member 47 is provided, for example, on the step surface 423 in the main body 42. Thus, the low reflectance member 47 is provided at a position where the light after being reflected once by the mask plate 44 is reflected by the inner surface of the trap space 424. As shown in FIG. 7, the low-reflectance member 47 preferably covers the inner surface of the main body 42 up to the peripheral edge of the inlet side opening 421. However, the low reflectance member 47 may be provided not only on the stepped surface 423 but also at another position on the inner surface of the trap space 424.

The surface of the low reflectance member 47 on the trap space 424 side (on the exit slit 45 side) is a low reflectance surface 471 that reflects light with low reflectance. As the structure of the low reflectance surface 471, the same structure as that in the case of FIG. 6 can be adopted.

In this example, at least part of the light that does not enter the effective area 61 of the diffraction grating 6 is reflected by the mask plate 44 provided between the entrance plate 43 and the diffraction grating 6, and then the inner surface (step difference) of the trap space 424. The low reflectance member 47 provided on the surface 423) attenuates and reflects the light. Therefore, stray light can be reduced more effectively.

In the above embodiment, the case where the incident portion having the incident slit 41 is a plate-like member such as the incident plate 43 or a member for attaching the optical fiber 10 such as the fiber attaching portion 46 has been described. However, not limited to such a configuration, the incident portion can be configured by any other member. Similarly, the mask portion is not limited to a plate-like member such as the mask plate 44, but can be formed of any other member.

Further, in the above embodiment, the case where the trap portion having the trap space 424 is configured by the main body 42 has been described. However, the configuration is not limited to such a configuration, and the configuration may be such that the trap portion is provided separately from the main body 42.

Furthermore, in the above embodiment, the case where the effective region 61 of the diffraction grating 6 is configured by a concave grating surface has been described. However, the effective area 61 of the diffraction grating 6 is not limited to such a configuration, and may be configured by a grating surface having another shape such as a flat surface. Further, the diffraction grating 11 is not limited to a reflection type diffraction grating that disperses light when reflecting the light in the effective area 61, but may be a transmission diffraction grating that disperses light when transmitting light in the effective area 61.

1 spectroscope 2 light source 3 condensing lens 4 incident light limiting member 5 first reflecting mirror 6 diffraction grating 7 second reflecting mirror 8 outgoing light limiting member 9 housing 10 optical fiber 11 diffraction grating 41 entrance slit 42 main body 43 entrance plate 44 mask Plate 45 Output slit 46 Fiber attachment part 47 Low reflectance member 61 Effective area 62 Rotation axis 81 Output slit 91 Opening 421 Entrance side opening 422 Exit side opening 423 Step surface 424 Trap space 461 Recess 471 Low reflectance surface

Claims (5)

An incident portion formed with an incident slit through which light from the light source passes,
A diffraction grating that diffracts the light that has passed through the incident slit in the effective area to disperse the light,
Of the light passing through the entrance slit, provided between the entrance section and the diffraction grating,
A mask portion that reflects and shields at least a part of light that does not enter the effective region;
A trap portion in which a trap space for attenuating the light reflected by the mask portion is formed ,
The spectroscope, wherein the mask part is detachably attached to the trap part . The diffraction grating is rotatably held around a rotation axis,
The mask portion reflects and shields light that does not enter the effective region in a state where the diffraction grating is rotated at least at a rotation position where the amount of light incident on the effective region is maximum. The spectroscope described in. The spectroscope according to claim 1, wherein the mask portion is provided with a low reflectance member that reflects light while attenuating the light. The spectroscope according to any one of claims 1 to 3, wherein a low-reflectance member that reflects light while attenuating the light is provided on an inner surface of the trap space. An incident light limiting member for limiting light from a light source that enters a spectroscope equipped with a diffraction grating,
An incident portion formed with an incident slit through which light from the light source passes,
Of the light passing through the entrance slit, provided between the entrance section and the diffraction grating,
A mask portion that reflects and shields at least a part of light that does not enter the effective area of the diffraction grating;
A trap portion in which a trap space for attenuating the light reflected by the mask portion is formed ,
The incident light limiting member , wherein the mask portion is detachably attached to the trap portion .

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