JPH05281041A - Spectroscope - Google Patents

Abstract

PURPOSE:To provide a compact spectroscope having a high resolution and a good S/N ratio. CONSTITUTION:A reflecting mirror 3 is positioned parallel and opposite to a Fresnel zone plate 2, and the reflecting mirror 3 is moved in the optical axis direction by a moving mechanism 4. When a collimated light is introduced into the Fresnel zone plate 2, only a light of specified wavelength transmits the Fresnel zone plate 2, and again transmits and returns after it is reflected from the reflecting mirror 3. The intensity of the returned light is measured by a detecting element such as a power meter. Further, spectrum of an incident light can be obtained by measuring the intensity of the light while the reflecting mirror 3 is moved by means of the moving mechanism 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to spectrometers. Specifically, for example, the present invention relates to a spectroscope for performing spectroscopic, detection, measurement, and the like of electromagnetic waves including X-rays and ultraviolet rays to infrared rays (hereinafter, also referred to as light including those outside the visible region).

[0002]

2. Description of the Related Art Spectrometers have been widely used since ancient times for the purpose of measuring the state of matter. For example, it is used for component analysis of gases such as nitrogen oxides contained in the atmosphere.

Up to now, a spectrometer using a diffraction grating having a linear or curved grating groove formed therein has been the mainstream. Since these utilize the fact that the diffraction angle of diffracted light differs depending on the wavelength, they have the following drawbacks.
That is, in order to increase the detection resolution, it is necessary to increase the distance (optical path length) between the diffraction grating and the detection element, which makes the optical system large and heavy, which makes it difficult to carry. It uses a lot of optical parts such as glass and is expensive. For this reason, the application has been limited mainly to research.

On the other hand, a spectroscope utilizing the fact that the Fresnel zone plate has a spectral characteristic has also been proposed (for example, JP-A-57-138613 and JP-A-63-2).
10631 gazette). For example, JP-A-57-138
As shown in FIG. 18, a spectroscope 51 disclosed in Japanese Patent No. 613 discloses a shield plate 54 in which a sample 53 is arranged in a through hole 52, a Fresnel zone plate 55, and a screen 5.
The light receiving element 58 provided behind the pinhole 57 of No. 6 is arranged along the optical axis, and the screen 56 and the light receiving element 58 are provided.
Are moved in the optical axis direction by the moving mechanism 59. Then, the light receiving element 58 is moved by the moving mechanism 59.
While moving the screen 56, the light emitted from the sample 53 is transmitted to the Fresnel zone plate 55, and the light collected by the Fresnel zone plate 55 at the position of the pinhole 57 is detected by the light receiving element 58.

However, such a spectroscope has a drawback of low resolution because it disperses light by utilizing the fact that the converging position of the Fresnel zone plate varies depending on the wavelength of light. In addition, since the light is blocked by the light-shielding portion (annular zone) of the Fresnel zone plate, the light utilization efficiency is poor. Furthermore, because a pinhole at the micron level is used, it is necessary to move the pinhole along the optical axis while controlling it with a precision of submicron so that the pinhole does not deviate from the optical axis. Met.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the drawbacks of the above-mentioned conventional examples, and its object is to achieve high resolution, high light (electromagnetic wave) utilization efficiency, and optical An object of the present invention is to provide a spectroscope which can be compactly assembled and which has a moderate accuracy required for a moving mechanism for obtaining a spectrum.

[0007]

The spectroscope of the present invention comprises a diffraction grating having a concentric circular pattern, a light reflecting means facing the diffraction grating, and collimated light from the side opposite to the light reflecting means to the diffraction grating. And a means for relatively moving the diffraction grating and the light reflecting means along the optical axis direction.

Another spectroscope of the present invention is a diffraction grating having a concentric circular pattern, a light reflecting means facing the diffraction grating, and a divergent light beam from the side opposite to the light reflecting means to the diffraction grating. Light emitting means for emitting light and means for relatively moving the diffraction grating and the light reflecting means along the optical axis direction are provided.

The light emitting means may be composed of an optical fiber.

The light emitting means may be composed of a semiconductor light emitting element. In this case, a wavelength adjusting means for modulating the emission wavelength of the semiconductor light emitting element may be provided.

The diffraction grating may be a Fresnel lens.

The area of the light reflecting region of the light reflecting means is preferably sufficiently smaller than the effective area of the diffraction grating.

The moving means may use a piezoelectric element as a drive source.

Further, light branching means for transmitting the light beam guided to the diffraction grating and reflecting return light reflected by the light reflecting means and transmitted through the diffraction grating, and light received by the light branching means are received. It may be provided with a detection means for performing.

The detecting means may be composed of a plurality of light receiving elements.

[0016]

In the spectroscope of the present invention, when an incident light beam (collimated light, divergent light) is incident on a diffraction grating having a concentric circular pattern, the light beam transmitted through the diffraction grating is reflected by the light reflecting means. , The reflected light beam (return light) passes through the diffraction grating again and returns to the original direction. At this time, the emission direction (or the convergence position) of the return light differs depending on the wavelength due to the spectral action of the diffraction grating. Therefore, the intensity of the light of the specific wavelength can be detected by detecting the return light in the specific emission direction (or the specific convergence position). In addition, since the folding optical system composed of the diffraction grating and the light reflecting means is used to reciprocate the light beam to one diffraction grating and exert the spectral effect twice, it is possible to improve the resolution of the light beam. it can. Moreover, since the folding optical system is used, the spectroscope can be made compact.

Further, since the light reflecting means or the diffraction grating may be moved by the moving means so as to maintain the parallelism, the required accuracy of the moving means can be moderated. Moreover, most of the optical system and the like can be integrated compactly.

Further, if the light emitting means is composed of an optical fiber, the light source can be made small, the light incident on the diffraction grating will have a low aberration, the S / N ratio will be improved, and the measurement resolution will be better.

Alternatively, if the light emitting means is constituted by a semiconductor light emitting element, a small light source having a wide emission wavelength from far infrared to visible light can be used, and the spectrometer can be made more compact.

If a Fresnel lens is used as the diffraction grating, the amount of transmitted light is increased, so that the light utilization efficiency is improved and the S / N ratio can be improved.

Further, if the area of the light reflecting region of the light reflecting means is made sufficiently smaller than the effective area of the diffraction grating, it is possible to prevent unnecessary light from being reflected by the light reflecting means, so that the resolution of the spectroscope is improved. The S / N ratio can be further improved.

Further, if a piezoelectric element is used as the moving means, the surface reflection of the light reflecting means and the like can be prevented and the displacement can be controlled accurately, so that the resolution of the spectroscope can be further improved.

Further, if the light branching means for transmitting the light beam guided to the diffraction grating and for reflecting the return light reflected by the reflecting means and transmitted through the diffraction grating is used, the return light can be separated from the incident light beam, so that the detection can be performed. The means can be easily installed, and the return light can be easily detected.

Further, if the detecting means is composed of a plurality of detecting elements, the light can be converged on the individual detecting elements for each wavelength, and the resolution can be further improved.

[0025]

1 shows a spectrometer 1 according to a first embodiment of the present invention.
It is a schematic block diagram which shows. Reference numeral 2 is a light-shielding portion (annular zone) having an extremely large absorption coefficient with respect to the used light and a light-transmitting portion (annular zone) having an extremely small absorption coefficient with respect to the used light, which are annular zones with unequal intervals The Fresnel zone plates are arranged concentrically and alternately. A reflecting mirror 3 is opposed to the Fresnel zone plate 2 in parallel, and the reflecting mirror 3 can be moved along the optical axis while being kept parallel to the Fresnel zone plate 2 by a moving mechanism 4. Although not shown in detail, as the moving mechanism 4 of the reflecting mirror 3, for example, a mechanical precision feeding mechanism including a screw mechanism and a DC servo motor or the like can be used. Collimated light is introduced into the Fresnel zone plate 2 from the side opposite to the reflecting mirror 3. The means for introducing the collimated light may be composed of a divergent light source that emits divergent light such as a semiconductor light emitting element and a collimator lens (see FIG. 13) that collimates the divergent light, or uses sunlight. In this case, the collimated light may be obtained by introducing sunlight from one or more slits or light receiving windows opened in the housing of the spectroscope 1 (not shown).

The Fresnel zone plate 2 has a spectral characteristic for electromagnetic waves from X-rays and ultraviolet rays to infrared rays. The focal length f differs depending on the incident wavelength λ of light, and the focal length f is inversely proportional to the incident wavelength λ. is doing. Therefore, if the reflecting mirror 3 is placed at a distance L from the Fresnel zone plate 2 that is equal to the focal length f corresponding to the specific wavelength, only the light of that wavelength out of the collimated light entering the Fresnel zone plate 2 is reflected by the reflecting mirror 3. After being reflected, further transmitted through the Fresnel zone plate 2 and returned, it becomes collimated light. On the other hand, the light beam having a wavelength other than the specific wavelength is reflected by the reflecting mirror 3, further passes through the Fresnel zone plate 2 and then returns to become divergent light (or once converged and then become divergent light).

Specifically, for example, when the reflecting mirror 3 is located at the focal position of the Fresnel zone plate 2 for the light of wavelength λ2, as shown in FIG.
If collimated light including light of λ3 (λ1>λ2> λ3) enters the Fresnel zone plate 2, the wavelength λ2
Is transmitted through the Fresnel zone plate 2, focused on the reflection mirror 3, reflected by the reflection mirror 3, transmitted through the Fresnel zone plate 2 again, and becomes collimated light. On the other hand, the light of the wavelength λ1 is transmitted through the Fresnel zone plate 2 to form a focus, and then is further diverged in the reflecting mirror 3
Is reflected by the light and is transmitted again through the Fresnel zone plate 2 to become divergent light. Further, the light having the wavelength λ3 is reflected by the reflecting mirror 3 before passing through the Fresnel zone plate 2 and being focused, and after passing through the Fresnel zone plate 2 again, is converged and further diverged.

Thus, the specific wavelength (λ in the above example)
Only the light of 2) returns to the original direction with a constant intensity I as collimated light, and the light of other wavelengths eventually diverges and the intensity I weakens, so it is sufficiently separated from the Fresnel zone plate 2. At the open position, only the light of the specific wavelength can be separated. Therefore, by guiding only this collimated light to a detection element (not shown) such as a power meter, it is possible to measure the intensity I of light of a specific wavelength determined by the distance between the Fresnel zone plate 2 and the reflecting mirror 3.

Further, when the reflecting mechanism 3 is moved along the optical axis by the moving mechanism 4, the distance between the reflecting mirror 3 and the Fresnel zone plate 2 continuously changes, whereby the light output as collimated light is changed. Since the wavelength changes continuously, the spectrum of the incident light beam can be measured. For example, when a light beam containing light of wavelengths λ1, λ2 and λ3 is incident as shown in FIG. 1, the intensity I of the returning light is measured by the detection element while moving the reflecting mirror 3 by the moving mechanism 4. Then, as shown in FIG. 2, the distance L between the Fresnel zone plate 2 and the reflecting mirror 3 is set to each wavelength λ1, λ2,
Focal length f of Fresnel zone plate 2 corresponding to λ3
A spectrum (bright line) is obtained when it becomes equal to 1, f2, and f3. Further, for example, when the light having the wavelengths λ11, λ12, ... Is absorbed by the gas in the atmosphere, the spectrum analysis by the spectroscope 1 is as shown in FIG.
An absorption spectrum (dark line) as shown in is observed.

FIG. 4 is a schematic configuration diagram showing a spectroscope 5 according to a second embodiment of the present invention. In this spectroscope 5, the micro Fresnel lens 6 is used as a non-uniformly spaced diffraction grating, the reflecting mirror 3 is opposed to the micro Fresnel lens 6, and the moving mechanism 4 moves the reflecting mirror 3 along the optical axis direction. I am trying.

The Fresnel zone plate 2 used in the spectroscope 1 of FIG. 1 has a structure in which the patterns of the light transmitting portions and the light shielding portions are alternately repeated in the radial direction. Only about half the amount of incident light passes through the Fresnel zone plate 2. Therefore,
In the spectroscope 1, there is a possibility that the S / N ratio may be deteriorated when the spectroscopic analysis of minute energy is performed.

On the other hand, the micro Fresnel lens 6 utilizing the light diffraction phenomenon and the refraction phenomenon has a better light utilization efficiency than the Fresnel zone plate 2. in addition,
Since the micro-Fresnel lens 6 has the same spectral characteristics as the Fresnel zone plate 2, the spectroscope 5 using the Fresnel zone plate 2 is a spectroscope 1 using the Fresnel zone plate 2 as the diffraction grating. By the same principle as described above, only the light of a specific wavelength can be extracted and measured by a detection element such as a power meter, and further, the S / N ratio can be improved by using the micro Fresnel lens 6.

FIG. 5 is a schematic configuration diagram showing a spectroscope 7 according to a third embodiment of the present invention. In this spectroscope 7, the reflecting mirror 3 is arranged so as to face the micro Fresnel lens 6, and the moving mechanism 4 moves the reflecting mirror 3 along the optical axis. Moreover, the diameter d of the reflecting mirror 3 is much smaller than the effective diameter (outer diameter of the pattern area) D of the micro Fresnel lens 6, and the reflecting mirror 3
Is aligned with the optical axis of the micro Fresnel lens 6 and fixed to the vertical plate portion 8 of the moving mechanism 4.

In the diffraction grating such as the Fresnel zone plate 2 and the micro Fresnel lens 6, generally, the 1st-order diffracted light is used for the spectroscopy, but it is known that the 0th-order diffracted light and the 2nd-order or higher-order diffracted light are simultaneously generated. However, the S / N ratio may be deteriorated due to the high-order diffracted light and the like. On the other hand, in the spectroscope 7 of the present embodiment, the area of the reflecting mirror 3 is made sufficiently smaller than the area of the effective region of the micro-Fresnel lens 6, so that the high-order diffracted light is reflected by the reflecting mirror 3.
It is designed to prevent reflection in the original direction by S / N
The ratio can be improved. Further, if the area of the reflecting mirror 3 is reduced to the diffraction limit value level of the first-order diffracted light, light having a wavelength that does not focus on the position of the reflecting mirror 3 (light other than a specific wavelength) is not reflected by the reflecting mirror 3, The wavelength resolution is improved. However, in this case, the center of the reflecting mirror 3 must always be exactly aligned with the optical axis of the micro Fresnel lens 6. Reflecting mirror 3 with such a small area
Can be produced by vapor-depositing a metal film or the like on the surface of the substrate using a mask, or the reflecting mirror 3
The reflecting mirror 3 may be exposed only at the pinhole position by bringing a shield plate with a pinhole into close contact with the surface of the.

FIG. 6 is a schematic block diagram showing a spectroscope 9 according to a fourth embodiment of the present invention. This spectroscope 9
Is a micro-Fresnel lens 6 facing a reflecting mirror 3 having a smaller effective diameter, and a half mirror 10 is arranged on the optical axis of the micro-Fresnel lens 6 opposite to the reflecting mirror 3 (light beam incident side). is there. This half mirror 10
Is used to transmit the incident light beam to the side of the micro-Fresnel lens 6 and reflect the return light from the side of the micro-Fresnel lens 6.

When the light beam to be spectroscopically measured is guided to the half mirror 10, the light beam passes through the half mirror 10 and the micro Fresnel lens 6 and the reflecting mirror 3
Is reflected by. The reflected light is again the Micro Fresnel lens 6
In the original direction, only light of a specific wavelength returns as collimated light and is reflected by the half mirror 10. As a result, only the light of the specific wavelength is extracted in the direction different from the original light beam. By installing the detection element in the direction in which the light of this specific wavelength is emitted, the intensity of the dispersed light can be easily measured.

The light beam reflected by the reflecting mirror 3, transmitted through the micro Fresnel lens 6 and returning returns along the same optical axis as the incident light beam. However, if the half mirror 10 is used as in this embodiment, The incident light beam and the return light can be separated, and only the return light can be easily detected.

As a light splitting means for the incident light beam and the return light, a bonded prism or the like which transmits a part of the light and refracts a part thereof may be used.

FIG. 7 is a schematic block diagram showing a spectroscope 11 according to a fifth embodiment of the present invention. This spectroscope 1
In 1, the optical system including a polarizer 12, a polarization beam splitter 13, and a quarter wavelength (λ / 4) plate is used as a light branching unit for effectively separating the incident light beam and the returning light beam. The polarizing beam splitter 13 is placed behind the polarizer 12, and the quarter-wave plate 1 is placed behind it.
4 is arranged, and the micro Fresnel lens 6 and the reflecting mirror 3 are arranged behind it. Here, the polarization beam splitter 13 can separate two linearly polarized lights whose polarization planes are orthogonal to each other in two directions. For example, P polarized light is transmitted and S polarized light is reflected.

When the unpolarized light beam is incident on the polarizer 12, it is converted into linearly polarized light (P-polarized) by the polarizer 12 and then incident on the polarization beam splitter 13. The P-polarized light passes through the polarization beam splitter 13,
Further, it is converted into circularly polarized light by passing through the quarter-wave plate 14. This circularly polarized light is a micro Fresnel lens 6
After being transmitted through the reflecting mirror 3, the micro Fresnel lens 6 transmits again, and only circularly polarized light of a specific wavelength becomes collimated light. The circularly polarized light of the specific wavelength that has become the collimated light is converted into linearly polarized light (S polarized light) by passing through the quarter-wave plate 14, and the S polarized light is reflected by the polarization beam splitter 13. Therefore, the intensity of this S-polarized light is measured by the detection element.

When a prism is used as the light splitting element, the reflected wave inside the prism may cause the S / N ratio to decrease, but it is composed of a polarization beam splitter 13 such as the spectroscope 11. By using the light branching means, it is possible to prevent the S / N ratio from decreasing. A polarization prism may be used instead of the polarization beam splitter 13.

FIG. 8 shows a spectroscope 15 according to a sixth embodiment of the present invention. The spectroscope 11 shown in FIG. 7 has a polarizer 12, a polarization beam splitter 13, and a quarter-wave plate 1.
4 and the micro Fresnel lens 6 are integrated. By using such an integrated structure, it is possible to improve the characteristics of the spectroscope 15 against vibrations and temperature changes, and to downsize the spectroscope 15.

FIG. 9 is a schematic configuration diagram showing a spectroscope 16 according to a seventh embodiment of the present invention. In this spectroscope 16, a prism 17 such as a bonded prism for transmitting a part of incident light and refracting a part of the incident light is arranged in front of the micro Fresnel lens 6, and a Fresnel lens, a refraction lens, etc. are provided on the side of the prism 17. The condenser lens 18 and the detecting element (light receiving element) 19 are arranged.

Thus, the incident light beam that has passed through the prism 17 passes through the micro-Fresnel lens 6 and the reflection mirror 3
Reflect on. Further, the light of a specific wavelength, which is reflected by the reflecting mirror 3 and transmitted through the micro Fresnel lens 6 and then becomes collimated light, is refracted by the prism 17 and then condensed by the condenser lens 18.
Then, the light is focused on and enters the detection element 19, and the intensity is measured by the detection element 19.

When a Fresnel lens is used as the condenser lens 18, the fact that the converging position of light differs depending on the wavelength is used, and a plurality of spectroscopes 20 (eighth embodiment) shown in FIG. 10 are used. By arranging the detecting elements 19a, 19b, ..., The individual detecting elements 19a, 19b,
Can be converged to ... And the resolution can be further improved.

FIG. 11 is a schematic configuration diagram showing a spectroscope 21 according to a ninth embodiment of the present invention. In this spectroscope 21, a prism 17 is provided in front of the micro Fresnel lens 6.
Is disposed, and the end surface of the optical fiber 22 faces the front of the prism 17. A detection element 19 having a small light receiving area is fixed to the side of the prism 17. The reflecting mirror 3 behind the micro Fresnel lens 6 is also very small.

When divergent light is emitted from the end face of the optical fiber 22 toward the prism 17, this light beam passes through the prism 17 and only light of a specific wavelength is reflected by the micro Fresnel lens 6 on the reflecting mirror 3. And is reflected by the reflecting mirror 3. The detection element 19 is the reflection mirror 3
It is arranged so that only the light of a specific wavelength that has been reflected by, and has passed through the micro Fresnel lens 6 is converged on the detection element 19 after being reflected by the prism 17. Therefore, since only the light of the specific wavelength is condensed on the detecting element 19, only the light of the specific wavelength can be dispersed by such a configuration. Further, when the reflecting mirror 3 is moved by the moving mechanism 4, the spectrum of the incident light can be obtained from the intensity measured by the detecting element 19.

When the light source is made small by using the optical fiber 22 in this way, the incident light on the micro Fresnel lens 6 has a low aberration, the S / N ratio is improved, and the measurement resolution is improved.

FIG. 12 shows a spectroscope 23 according to the tenth embodiment of the present invention. In this embodiment, a collimator lens 24 is inserted between the optical fiber 22 and the prism 17, divergent light emitted from the end face of the optical fiber 22 is converted into collimated light by the collimator lens 24, and then the prism 17 is used. It is incident on.
Further, the separated collimated light of a specific wavelength is condensed on the detection element 19 by the condenser lens 18. As described above, if the light beam emitted from the optical fiber 22 is converted into collimated light and then incident on the prism 17, the aberration due to the prism 17 or the like can be further reduced.

FIG. 13 is a schematic configuration diagram showing a spectroscope 25 according to an eleventh embodiment of the present invention. In this spectroscope 26, the collimator lens 24, the prism 17, the micro-Fresnel lens 6 and the condenser lens 18 are integrated, and the characteristics can be stabilized against vibration and temperature change, and the spectroscope can be made more compact. ..

FIG. 14 is a schematic configuration diagram showing a spectroscope 26 according to a twelfth embodiment of the present invention. In the spectroscope 26, a semiconductor light emitting element 27 such as an LED or a semiconductor laser is used as a light source, divergent light emitted from the light emitting element 27 is converted into collimated light by a collimator lens 24, and the collimated light is converted into a prism 17. After passing through
Light having a specific wavelength is extracted as collimated light by the micro Fresnel lens 6 and the small reflecting mirror 3, reflected by the prism 17, and then condensed by the condenser lens 18 on the detection element 19.

The spectroscope 26 uses the semiconductor light emitting element 27 as a light source, but since the light emitting element 27 has a minute light emitting point and has a small shape, it is useful for downsizing the spectroscope 26. Further, since the light emitting element 27 has a wide emission wavelength from far infrared to visible light, it is suitable as a light source for a spectroscope.

Further, the spectroscope 26 is provided with a light emitting element modulation drive circuit 28 capable of modulating the drive current of the semiconductor light emitting element 27 so that the emission wavelength can be scanned by modulating the drive current value. Is becoming

FIG. 15 is a schematic configuration diagram showing a spectroscope 29 according to a thirteenth embodiment of the present invention. In this spectroscope 29, the semiconductor light emitting element 27 is caused to emit light by the light emitting element drive circuit 30, and the case 31 in which the light emitting element 27 is housed
A case temperature control device 32 for changing the temperature of the case by heating the heater is provided, and the emission wavelength of the light emitting element 27 can be scanned by changing the temperature of the case 31.

FIG. 16 shows an embodiment for explaining a specific structure of the moving mechanism 4 for changing the relative distance between the diffraction grating 33 such as a micro Fresnel lens or a Fresnel zone plate and the reflecting mirror 3. The moving mechanism 4 using the laminated piezoelectric element 34 is shown. One or more laminated piezoelectric elements 34 are fixed to the fixed base 35 in parallel with each other, and the reflection mirror 3 is attached to the free end of each laminated piezoelectric element 34.
The back side of is fixed.

When a driving voltage is applied to the laminated piezoelectric element 34 to expand and contract, the reflecting mirror 3 supported by the laminated piezoelectric element 34 is displaced and fixed to the diffraction grating 3.
The distance between 3 and the reflecting mirror 3 changes. Multilayer piezoelectric element 34
Is a small and precise actuator that changes its shape in proportion to the input voltage. It has less backlash and trouble, and has less moving parts than methods such as motor drive, and is characterized by strong vibration. is there. Therefore, by using the laminated piezoelectric element 34 as the moving mechanism 4,
Since the tilt of the reflecting mirror 3 can be prevented and the displacement can be accurately controlled, the resolution of the spectroscope can be improved.

FIG. 17 shows another embodiment of the specific structure of the moving mechanism 4 for changing the relative distance between the diffraction grating 33 and the reflecting mirror 3. In this embodiment, a displacement magnifying mechanism 36 is provided at both ends of the laminated piezoelectric element 34, and a plurality of laminated piezoelectric elements 34 having the displacement magnifying mechanism 36 at both ends are connected in cascade. The displacement magnifying mechanism 36 is formed in a bridge shape or a dome shape, converts the lateral strain of the laminated piezoelectric element 34 into a longitudinal strain and amplifies it, and superimposes it on the longitudinal strain of the laminated piezoelectric element 34. Then, a large displacement amount is output from the laminated piezoelectric element 34. By using the moving mechanism 4 as described above, the reflecting mirror 3 can be displaced or moved largely as compared with the embodiment of FIG.

Although the reflecting mechanism is moved by the moving mechanism in the above embodiment, the reflecting mirror may be fixed and the diffraction grating may be moved by the moving mechanism. Alternatively, the relative distance may be changed by simultaneously moving the reflecting mirror and the diffraction grating by the moving mechanism. Further, in the above embodiment, for example, the case of analyzing a gas component (nitrogen oxide, etc.) in the air has been described in mind, but the light incident side (for example, near the end face of the optical fiber in the embodiment of FIG. 11) If a transparent sample is placed on the sample, it can be used for analysis of the sample.

[0059]

According to the present invention, the intensity of light of a specific wavelength can be detected by detecting the light in the specific emission direction (or the specific convergence position) of the return light, and the diffraction Since the folding optical system composed of the grating and the light reflecting means is used to reciprocate the light beam to one diffraction grating and exert the spectral effect twice, it is possible to improve the resolution of the light beam. Moreover, since the folding optical system is used, the spectroscope can be made compact, and a portable spectroscope can be manufactured, and the application is expanded.

Further, since the light reflecting means or the diffraction grating may be moved by the moving means so as to maintain the parallelism, the required accuracy of the moving means can be moderated. Moreover, most of the optical system and the like can be integrated compactly, and a spectroscope having excellent characteristics against vibration and temperature change can be manufactured.

Further, by using an optical fiber or a semiconductor light emitting element as the light emitting means, the S / N ratio of the spectroscope can be improved and the spectroscope can be made more compact.

Further, if the area of the light reflecting region of the light reflecting means is made sufficiently smaller than the effective area of the diffraction grating, it is possible to prevent unnecessary light from being reflected by the light reflecting means, so that the resolution of the spectroscope is improved. The S / N ratio can be further improved.

Furthermore, a small-sized and highly accurate piezoelectric element can be used as the moving means, and the resolution of the spectroscope can be further improved.

Further, if the light branching means for transmitting the light beam guided to the diffraction grating and reflecting the return light reflected by the reflecting means and transmitted through the diffraction grating is used, the return light can be separated from the incident light beam. The means can be easily installed, and the return light can be easily detected.

Further, if the detecting means is composed of a plurality of detecting elements, the light can be converged on the individual detecting elements for each wavelength, and the resolution can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a spectroscope according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of a spectrum obtained by the spectroscope of the same.

FIG. 3 is a diagram showing an absorption spectrum of another light beam.

FIG. 4 is a schematic configuration diagram showing a spectroscope according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a spectroscope according to a third embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing a spectroscope according to a fourth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a spectroscope according to a fifth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a spectroscope according to a sixth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram showing a spectroscope according to a seventh embodiment of the present invention.

FIG. 10 is a schematic configuration diagram showing a spectroscope according to an eighth embodiment of the present invention.

FIG. 11 is a schematic configuration diagram showing a spectroscope according to a ninth embodiment of the present invention.

FIG. 12 is a schematic configuration diagram showing a spectroscope according to a tenth embodiment of the present invention.

FIG. 13 is a schematic configuration diagram showing a spectroscope according to an eleventh embodiment of the present invention.

FIG. 14 is a schematic configuration diagram showing a spectroscope according to a twelfth embodiment of the present invention.

FIG. 15 is a schematic configuration diagram showing a spectroscope according to a thirteenth embodiment of the present invention.

FIG. 16 is a schematic configuration diagram showing a spectroscope according to a fourteenth embodiment of the present invention.

FIG. 17 is a schematic configuration diagram showing a spectroscope according to a fifteenth embodiment of the present invention.

FIG. 18 is a schematic configuration diagram showing a conventional spectroscope.

[Explanation of symbols]

 2 Fresnel zone plate 3 Reflector 4 Moving mechanism 6 Micro Fresnel lens 10 Half mirror 13 Polarizing beam splitter 17 Prism 19 Detection element 22 Optical fiber 27 Light emitting element 34 Laminated piezoelectric element

Claims (10)

[Claims] 1. A diffraction grating having a concentric pattern, a light reflecting means facing the diffraction grating, a means for guiding collimated light from the side opposite to the light reflecting means to the diffraction grating, and the diffraction grating. A spectroscope comprising means for relatively moving the light reflecting means along the optical axis direction. 2. A diffraction grating having a concentric pattern, a light reflecting means facing the diffraction grating, a light emitting means for emitting a divergent light beam to the diffraction grating from the side opposite to the light reflecting means, and the diffraction A spectroscope comprising a grating and means for relatively moving the light reflecting means along the optical axis direction. 3. The spectroscope according to claim 2, wherein the light emitting means is constituted by an optical fiber. 4. The spectroscope according to claim 2, wherein the light emitting means is composed of a semiconductor light emitting element. 5. The spectroscope according to claim 4, wherein the light emitting unit includes a wavelength adjusting unit that modulates an emission wavelength of the semiconductor light emitting element. 6. The spectroscope according to claim 1, 2, 3, 4 or 5, wherein the diffraction grating is a Fresnel lens. 7. The area of the light reflecting region of the light reflecting means is
The spectroscope according to claim 1, 2, 3, 4, 5 or 6, which is sufficiently smaller than the effective area of the diffraction grating. 8. The moving means uses a piezoelectric element as a driving source, and the moving means uses the piezoelectric element.
6. The spectroscope according to 6 or 7. 9. Light splitting means for transmitting a light beam guided to the diffraction grating and reflecting return light reflected by the light reflecting means and transmitted through the diffraction grating, and light split by the light splitting means. 9. A detecting means for receiving light is included.
The spectroscope described in. 10. The spectroscope according to claim 9, wherein the detection means comprises a plurality of detection elements.