JP7735889B2 - Spectroscopic and analytical equipment - Google Patents

Description

The present invention relates to a spectrometer and an analytical device.

Conventionally, so-called spectroscopes have been known that separate measurement light into wavelengths to obtain an optical spectrum for each wavelength.

The spectrometer is configured to collect light reflected by a reflecting means with a variable tilt of the reflecting surface using a confocal optical system, disperse the collected light into different directions for each wavelength using a diffraction grating, and emit only light of a certain wavelength from the dispersed light using a slit mirror (see, for example, Patent Document 1).

However, with the configuration of Patent Document 1, the light utilization efficiency and the intensity of stray light emitted from the light emitting means, such as a slitted mirror, can change depending on the angle of incidence of light of different wavelengths contained in the wavelength-dispersed light that enters the light emitting means. Changes in the light utilization efficiency and the intensity of stray light reduce the spectroscopic accuracy of the spectroscope.

The present invention aims to improve the spectroscopic accuracy of a spectrometer in order to solve the problems of the conventional technology described above.

In order to solve the above-mentioned problems, the spectrometer of the present invention comprises a light incident means that incidents light from outside through a first light passing portion, a diffraction grating that wavelength-disperses the light incident by the light incident means, a reflecting means that has a reflecting surface that reflects the wavelength-dispersed light by the diffraction grating and the inclination of the reflecting surface is variable, and a light emitting means that emits a portion of light of different wavelengths contained in the wavelength-dispersed light reflected by the reflecting means to the outside through a second light passing portion, and satisfies the conditions of the following equations (1) and (2).
|θr|<|θm| ...(1)
|θr|<|θM| ...(2)
(λm represents the minimum wavelength in the wavelength-dispersed light, λM represents the maximum wavelength in the wavelength-dispersed light, λr represents a wavelength selected from the range between λm and λM among the different wavelengths in the wavelength-dispersed light, θm represents the angle of incidence at which light of wavelength λm is incident on the second light passing portion, θM represents the angle of incidence at which light of wavelength λM is incident on the second light passing portion, and θr represents the angle of incidence at which light of wavelength λr is incident on the second light passing portion.)

This invention can improve the spectroscopic accuracy of a spectrometer.

1 is a perspective view illustrating an example of the overall configuration of a spectrometer according to a first embodiment. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 3A and 3B are diagrams illustrating the arrangement of a light emitting unit and a light detecting unit according to the first embodiment; 4A is a diagram of the incident angle θM, FIG. 4B is a diagram of the incident angle θr, and FIG. 4C is a diagram of the incident angle θm. 5A is a diagram of the incident angle θM; FIG. 5B is a diagram of the incident angle θr; and FIG. 5C is a diagram of the incident angle θm. 6A is a diagram of the incident angle θM; FIG. 6B is a diagram of the incident angle θr; and FIG. 6C is a diagram of the incident angle θm. FIG. 1 is a first diagram showing an example of change in light utilization efficiency depending on the incident angle. FIG. 2 is a second diagram showing an example of change in light utilization efficiency depending on the incident angle. FIG. 3 is a third diagram showing an example of change in light utilization efficiency depending on the incident angle. 10A and 10B are diagrams illustrating a projected image of a light incident portion according to a second embodiment. 10A and 10B are diagrams illustrating a projected image of a light exit portion according to a second embodiment. FIG. 10 is a cross-sectional view of a light incident portion and a light emitting portion according to a third embodiment. FIG. 10 is a cross-sectional view of a light incident portion and a light emitting portion according to a first modified example. FIG. 10 is a cross-sectional view of a light incident portion and a light emitting portion according to a second modified example. 10A and 10B are diagrams illustrating the intensity of reflected light at a non-light passing portion according to the third embodiment. 10A and 10B are diagrams illustrating reflection on an inner wall of a light transmitting portion according to the third embodiment.

The following describes in detail the embodiments of the invention with reference to the drawings. In each drawing, identical components are designated by the same reference numerals, and duplicate explanations will be omitted where appropriate.

The embodiments described below are examples of spectrometers and analytical devices that embody the technical concepts of the present disclosure, and are not intended to limit the present disclosure to the embodiments described below. Unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended for illustrative purposes only and are not intended to limit the scope of the present disclosure. Furthermore, the sizes and relative positions of components shown in the drawings may be exaggerated for clarity.

[Embodiment]
<Example of overall configuration of spectroscope 10>
1 is a perspective view illustrating the overall configuration of a spectrometer 10 according to an embodiment. The spectrometer 10 includes a light input unit 1, a concave diffraction grating 2, a movable light reflector 3, a light output unit 4, a substrate 5, and a light detector 6.

The light incident section 1 is an example of a light incident means that allows external light Li to enter through the first light passing section 11. The area of the light incident section 1 other than the first light passing section 11 constitutes a first non-light passing section 12 that does not allow light Li to pass through.

The first light passing section 11 has, for example, a pinhole or slit shape, and is provided to determine the incident position of light and improve wavelength resolution.

The concave diffraction grating 2 is an example of a diffraction grating that wavelength-disperses the light Li incident through the light incident portion 1. The concave diffraction grating 2 is formed on a substrate 5. The concave diffraction grating 2 diffracts the light Li to wavelength-disperse it, and reflects the wavelength-dispersed light Ld toward the movable light reflector 3. The light of different wavelengths contained in the wavelength-dispersed light Ld propagates while converging, impinging on different positions on the reflection line 33 on the reflection surface 32 and being reflected by the reflection surface 32.

The substrate 5 may be made of, but is not limited to, a semiconductor, glass, metal, or resin. The concave diffraction grating 2 may be formed directly on the substrate 5, or may be formed on a thin film layer, such as a resin layer, formed on the substrate 5.

The movable light reflector 3 has a reflecting surface 32 that reflects the wavelength-dispersed light Ld generated by the concave diffraction grating 2, and is an example of a reflecting means in which the inclination of the reflecting surface is variable. The movable light reflector 3 reflects the wavelength-dispersed light Ld generated by the concave diffraction grating 2 toward the light output unit 4 using the reflecting surface 32.

The movable light reflecting unit 3 has a swing axis 31. By swinging around the swing axis 31, the movable light reflecting unit 3 can change the inclination of the reflecting surface 32 that reflects the wavelength-dispersed light Ld.

The movable light reflector 3 can be formed thin and small on a semiconductor substrate using, for example, a semiconductor process or a MEMS (Micro Electro Mechanical Systems) process. Furthermore, by forming the movable light reflector 3 on a semiconductor substrate, it is possible to monolithically form a driving element unit, such as a piezoelectric, electrostatic, or electromagnetic drive, on the semiconductor substrate. This allows the spectrometer 10 to drive the movable light reflector 3 without using an external driving device such as a motor, thereby enabling further miniaturization. However, the substrate on which the movable light reflector 3 is formed is not limited to semiconductor, and may be glass, metal, resin, etc.

The light output unit 4 is an example of a light output means that outputs a portion of the light of different wavelengths contained in the wavelength-dispersed light Ld reflected by the movable light reflector 3 to the outside through the second light passing unit 41. The portion of the light of different wavelengths contained in the wavelength-dispersed light Ld is output to the outside through the second light passing unit 41 at its approximate focal position. The area of the light output unit 4 other than the second light passing unit 41 constitutes a second light non-passing unit 42 that does not allow the wavelength-dispersed light Ld to pass through.

The second light passing section 41 has, for example, a pinhole or slit shape, and is provided to determine the emission position of some of the light of different wavelengths contained in the wavelength-dispersed light Ld and to improve wavelength resolution.

Light of different wavelengths contained in the wavelength-dispersed light Ld is reflected at different positions on the reflection line 33 on the reflecting surface 32 and enters different positions on the emission line 43 on the light emitting section 4.

By changing the tilt of the reflecting surface 32 of the movable light reflecting unit 3 around the oscillation axis 31, the incident position on the emission line 43 of each light of different wavelengths contained in the wavelength-dispersed light Ld changes.

Of the light of different wavelengths contained in the wavelength-dispersed light Ld, light that is incident on the position of the second light passing section 41 is emitted through the second light passing section 41. The light emitting section 4 can emit light of a wavelength contained in the wavelength-dispersed light Ld, the wavelength of which is determined by the oscillation angle of the movable light reflecting section 3, through the second light passing section 41.

The light incident portion 1 and light exit portion 4 may also be formed on a substrate. In this case, the substrate may be made of, for example, semiconductor, glass, metal, resin, etc., but is not limited to these. However, using a semiconductor as the substrate material is preferable, as it allows the light incident portion 1 and light exit portion 4 to be formed with high precision and low cost using semiconductor processes, MEMS processes, etc.

The light detection unit 6 is an example of a light detection means that detects the light emitted from the light emission unit 4. The light detection unit 6 can be, for example, a photodiode. When dispersing light Li in the near-infrared region, an InGaAs photodiode is preferred.

In the spectrometer 10, each of the above components is arranged in a predetermined position as shown in Figure 1, and is fixed to a housing, jig, etc. so that it can maintain a predetermined posture.

<Configuration example of concave diffraction grating 2>
FIG. 2 is a diagram illustrating the configuration of the concave diffraction grating 2, and is a cross-sectional view taken along the line II-II in FIG.

As shown in Figure 2, the concave diffraction grating 2 has a reflective member 15. Specifically, a concave curved surface is formed on the upper surface of the substrate 5, and a diffraction grating is formed on this concave curved surface. Furthermore, a reflective member 15 made of a metal material such as Al, Ag, Au, or Pt is formed on the surface of the diffraction grating to improve reflectivity. For example, a diffraction grating can be formed on the concave curved surface of the substrate 5 by applying resist to the concave curved surface of the substrate 5, forming a grating pattern in the resist using interference exposure or the like, and then performing dry etching or the like.

The concave diffraction grating 2 can have, for example, a rectangular, sinusoidal, or sawtooth wave cross-sectional shape for the grooves of the diffraction grating.

The concave diffraction grating 2 may be configured without the reflective member 15. Furthermore, the configuration of the concave diffraction grating 2 is not limited to that illustrated in Figure 2, as long as it has a similar wavelength dispersion function. When parallel light is incident from the light incident section 1, a similar wavelength dispersion function can be obtained by using a planar diffraction grating instead of the concave diffraction grating 2. In this case, there is no need for the complex device configuration (for example, a collimating optical system for collimating light before and after the planar diffraction grating) that would be required if a configuration that changes the inclination of the planar diffraction grating is adopted.

In the concave diffraction grating 2, a thin-film resin layer may be formed on the concave curved surface formed on the upper surface of the substrate 5, and the diffraction grating may be formed on this resin layer. In this case, to improve reflectivity, it is preferable to form a reflective member made of a metal material such as Al, Ag, Au, or Pt on the surface of the diffraction grating formed on the resin layer.

<Example of arrangement of light emitting unit 4 and light detecting unit 6>
FIG. 3 is a diagram illustrating the arrangement of the light emitting unit 4 and the light detecting unit 6, and is a side view of the light emitting unit 4 and the light detecting unit 6. As shown in FIG.

As shown in Figure 3, the light emitting unit 4 is arranged so as to be in contact with the light detecting unit 6. The light detecting unit 6 supports the light emitting unit 4 by adhering the light emitting unit 4 with an adhesive or pressure-sensitive adhesive material, etc.

The adhesive or pressure-sensitive adhesive used to bond the light emitting unit 4 and the light detecting unit 6 can be made of thermoplastic resin, thermosetting resin, rubber or elastomer, silicone, or knitted silicone. Because the temperature of the light detecting unit 6 may rise due to power consumption, it is desirable that the adhesive or pressure-sensitive adhesive have excellent stress relaxation properties to suppress thermal deformation of the light emitting unit 4. The light detecting unit 6 may also be adhesively supported by the light emitting unit 4 in close proximity to it via a member other than the adhesive, without coming into contact with the light emitting unit 4.

The light detection unit 6 includes a light receiving window 61. The emitted light that passes through the second light passing portion 41 of the light emission unit 4 is detected by the light detection unit 6 through the light receiving window 61.

The incident angle θr represents the angle at which light Lr of a predetermined wavelength λr, among the different wavelengths contained in the wavelength-dispersed light Ld, enters the light output unit 4. More specifically, the incident angle θr is the angle between the light-receiving central axis 60, which passes through approximately the center of the light-receiving window 61 and extends in an approximately normal direction to the light-receiving window 61, and the optical axis Lr1, which is the central axis of light Lr. The optical axis Lr1 can also be considered the principal ray of light Lr.

Here, if the light emitting section and the light detecting section are spaced apart along the light receiving central axis 60, and the incident angle θr is large, the distance between the incident position of light Lr that has passed through the second light passing section into the light detecting section and the light receiving central axis 60 becomes long, so light Lr may not enter the light receiving window of the light detecting section and may not be detected by the light detecting section.

In this embodiment, the light detection unit 6 is arranged so that it is in contact with or close to the light emission unit 4, so that the incident position of light Lr on the light detection unit 6 can be brought closer to the light-receiving central axis 60, even when the incident angle θr is large. As a result, even when the incident angle θr is large, light Lr is incident on the light-receiving window 61, allowing the light detection unit 6 to detect light Lr.

Furthermore, if the light emitting unit and the light detecting unit are spaced apart along the light-receiving central axis 60 and are supported by separate members, the relative position between the light emitting unit and the light detecting unit is likely to fluctuate. In this embodiment, the light detecting unit 6 supports the light emitting unit 4, making it possible to suppress fluctuations in the relative position between the light emitting unit 4 and the light detecting unit 6.

<Relationship between the angle of incidence on the light emitting portion 4, the light utilization efficiency, and stray light>
4 to 6 are diagrams illustrating the angle of incidence on the light emitting portion 4. Fig. 4 is Fig. 1, in which Fig. 4(a) is a diagram of the angle of incidence θM, Fig. 4(b) is a diagram of the angle of incidence θr, and Fig. 4(c) is a diagram of the angle of incidence θm. Fig. 5 is Fig. 2, in which Fig. 5(a) is a diagram of the angle of incidence θM, Fig. 5(b) is a diagram of the angle of incidence θr, and Fig. 5(c) is a diagram of the angle of incidence θm. Fig. 6 is Fig. 3, in which Fig. 6(a) is a diagram of the angle of incidence θM, Fig. 6(b) is a diagram of the angle of incidence θr, and Fig. 6(c) is a diagram of the angle of incidence θm.

In this embodiment, the relationship between the angles of incidence θM, θr, and θm is expressed by the following equations (1) and (2).
|θr|<|θm| ...(1)
|θr|<|θM| ...(2)

Here, λm represents the minimum wavelength in the wavelength-dispersed light Ld. λM represents the maximum wavelength in the wavelength-dispersed light Ld. λr represents a wavelength selected from the range between λm and λM among the different wavelengths in the wavelength-dispersed light Ld. Furthermore, θm represents the angle of incidence at which light Lm of wavelength λm enters the second light passing section 41. θM represents the angle of incidence at which light LM of wavelength λM enters the second light passing section 41. θr represents the angle of incidence at which light Lr of wavelength λr enters the second light passing section 41.

More specifically, the incident angle θm is the angle between the light-receiving central axis 60 and the optical axis Lm1, which is the central axis of light Lm. The incident angle θM is the angle between the light-receiving central axis 60 and the optical axis LM1, which is the central axis of light LM. The incident angle θr is the angle between the light-receiving central axis 60 and the optical axis Lr1, which is the central axis of light Lr. The optical axis Lm1 can also be referred to as the chief ray of light Lm, the optical axis LM1 as the chief ray of light LM, and the optical axis Lr1 as the chief ray of light Lr.

In Figures 4 to 6, the arrangement is such that when the tilt angle of the reflecting surface 32 of the movable light reflecting unit 3 around the oscillation axis 31 is small, light LM passes through the second light passing portion 41, and when the tilt angle of the reflecting surface 32 around the oscillation axis 31 is large, light Lm passes through the second light passing portion 41.

As shown in Figure 4, in response to changes in the inclination of the reflecting surface 32 of the movable light reflecting unit 3, the incident position of each of the different wavelengths of light contained in the wavelength-dispersed light Ld on the light emitting unit 4 changes, and the incident angle on the second light passing unit 41 also changes.

The amount of light passing through the second light passing section 41 varies depending on the angle of incidence. As the angle of incidence increases, more light cannot pass through the second light passing section 41, reducing the light utilization efficiency of the spectroscope 10.

By satisfying the conditions of equations (1) and (2) above, the differences between the incident angles θm, θM, and θr become smaller, thereby improving the light utilization efficiency of light Lm, LM, and Lr.

Figures 5 and 6 show the relationship between the incident angles θm, θM, and θr when the inclination of the light output portion 4 is changed compared to Figure 4. In the example of Figure 5, by arranging the incident angle θM to be approximately 0 degrees, the relationship |θM|<|θr|<|θm| is achieved. In the example of Figure 6, by arranging the incident angle θm to be approximately 0 degrees, the relationship |θm|<|θr|<|θM| is achieved.

Here, of the wavelength-dispersed light Ld incident on the light output unit 4, light that cannot pass through the second light-passing section 41 may become stray light after being reflected by the second non-light-passing section 42 of the light output unit 4. Note that stray light refers to light that does not contribute to the splitting by the spectroscope 10.

In the arrangement shown in Figure 4, most of the light reflected by the second non-light-passing portion 42 travels back along the same optical path as the light it came from, and is guided in this order through the movable light reflecting portion 3, the concave diffraction grating 2, and the light incident portion 1, with some of that light being reflected by the first non-light-passing portion 12 in the light incident portion 1.

The light reflected by the first non-light-passing portion 12 is guided again through the concave diffraction grating 2, the movable light reflecting portion 3, and the second non-light-passing portion 42, in that order, and some of the light is reflected by the second non-light-passing portion 42.

As described above, light reflected by the second non-light-transmitting portion 42 is multiple-reflected between the light-emitting portion 4 and the light-incident portion 1. For example, if the reflectivity of each of the first non-light-transmitting portion 12 and the second non-light-transmitting portion 42 is reduced, the multiple-reflected light will be extinguished as the number of reflections increases, thereby suppressing stray light caused by this multiple-reflected light.

On the other hand, in the arrangement shown in Figure 5, the incident angles θm, θM, and θr have the relationship |θM| < |θr| < |θm|, so the light Lm reflected by the second non-light-passing portion 42 does not travel back along the optical path it came from, but is reflected by the support members that support the light incident portion 1, concave diffraction grating 2, movable light reflecting portion 3, and light emitting portion 4, and is therefore likely to become stray light.

Similarly, in the case of the arrangement shown in Figure 6, the incident angles θm, θM, and θr have the relationship |θm| < |θr| < |θM|, so the light LM reflected by the second non-light-passing portion 42 does not travel back along the optical path it came from, but is reflected by the support members that support the light incident portion 1, concave diffraction grating 2, movable light reflecting portion 3, and light emitting portion 4, and is therefore likely to become stray light.

From the above, in the arrangement shown in Figure 4, if the conditions of equations (1) and (2) above are satisfied, the effect of suppressing the generation of stray light is enhanced.

<Simulation results of light utilization efficiency>
7 to 9 are diagrams showing examples of changes in light use efficiency according to the angle of incidence on the second light passing portion 41, with Fig. 7 being Fig. 1, Fig. 8 being Fig. 2, and Fig. 9 being Fig. 3. All of Fig. 7 to Fig. 9 show the results of calculating the light use efficiency according to the angle of incidence through a simulation using illumination analysis software. In each diagram, the horizontal axis represents the angle of incidence on the second light passing portion 41, and the vertical axis represents the normalized light use efficiency.

The simulation results shown in each figure are for an arrangement in which light LM passes through the second light passing portion 41 when the tilt angle of the reflecting surface 32 of the movable light reflecting portion 3 around the oscillation axis 31 is small, and light Lm passes through the second light passing portion 41 when the tilt angle of the reflecting surface 32 around the oscillation axis 31 is large.

Figure 7 shows the case where equations (1) and (2) are satisfied, Figure 8 shows the case where the relationship |θM|<|θr|<|θm| holds, and Figure 9 shows the case where the relationship |θm|<|θr|<|θM| holds.

The ratio of the minimum to the maximum light utilization efficiency was approximately 89% in Figure 7, approximately 81% in Figure 8, and approximately 74% in Figure 9. This demonstrates that excellent light utilization efficiency can be achieved by satisfying the conditions of equations (1) and (2) above.

<Functions and Effects of Spectrometer 10>
As described above, the spectrometer 10 includes a light incident section 1 (light incident means) that allows external light Li to enter through the first light passing section 11, and a concave diffraction grating 2 (diffraction grating) that wavelength-disperses the light Li incident by the light incident section 1. The spectrometer 10 also includes a movable light reflector 3 (reflection means) that has a reflecting surface 32 that reflects wavelength-dispersed light Ld by the concave diffraction grating 2 and whose inclination is variable, and a light exit section 4 (light exit means) that exits a portion of light of different wavelengths contained in the wavelength-dispersed light Ld reflected by the movable light reflector 3 to the outside through the second light passing section 41. The spectrometer 10 satisfies the conditions of the above formulas (1) and (2).

By satisfying the conditions of equations (1) and (2) above, the differences between the incident angles θm, θM, and θr become smaller, and therefore the light utilization efficiency of the light Lm, LM, and Lr emitted from the light emitting unit 4 in the spectrometer 10 is improved. Since the signal-to-noise ratio in the light detecting unit 6 increases due to the improved light utilization efficiency, the spectroscopic accuracy of the spectrometer 10 can be improved in this embodiment.

Furthermore, by satisfying the conditions of equations (1) and (2) above, the light reflected by the second non-light-passing portion 42 is multiple-reflected between the light exit portion 4 and the light entrance portion 1. For this reason, for example, if the reflectivity of each of the first non-light-passing portion 12 and the second non-light-passing portion 42 is reduced, the multiple-reflected light will extinguish as the number of reflections in the multiple reflections increases. Therefore, in the spectrometer 10, stray light due to light reflected by the support members that support the light entrance portion 1, concave diffraction grating 2, movable light reflecting portion 3, and light exit portion 4 can be suppressed, and the signal-to-noise ratio in the light detection portion 6 can be increased.

In addition, in this embodiment, the spectrometer 10 has a light detection unit 6 (light detection means) that detects light emitted from the light emission unit 4, and the light detection unit 6 is arranged so as to be in contact with or in close proximity to the light emission unit 4. This makes it possible to suppress light that does not enter the light receiving window 61 and is therefore not detected by the light detection unit 6, even when the incident angle θr is large, thereby improving light utilization efficiency and improving the spectroscopic accuracy of the spectrometer 10.

In addition, in this embodiment, the light detection unit 6 supports the light emission unit 4, which can suppress relative positional fluctuations between the light emission unit 4 and the light detection unit 6, thereby improving the spectroscopic accuracy of the spectrometer 10.

Second Embodiment
Next, a second embodiment of the spectrometer 10 will be described. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. This also applies to the following embodiments.

<Example of relationship between shape of first light passing portion 11 and shape of second light passing portion 41>
Fig. 10 is a diagram illustrating a projected image 1s of the light entrance portion 1 according to this embodiment. Fig. 11 is a diagram illustrating a projected image 4s of the light exit portion 4 according to this embodiment.

Figure 10 shows how light Li passes through the first light passing section 11 of the light incident section 1. The projected image 1s is a projected image of the first light passing section 11 projected onto a plane Pi perpendicular to the principal ray Li0 of light Li passing through the first light passing section 11.

Figure 11 shows how light Lr with wavelength λr, among the light of different wavelengths contained in the wavelength-dispersed light Ld, passes through the second light passing section 41 of the light output section 4. The projected image 4s is a projected image of the second light passing section 41 projected onto a plane Pr perpendicular to the chief ray Lr0 of the light Lr passing through the second light passing section 41.

In this embodiment, the spectrometer 10 is configured so that the shape of the projected image 1s is equal to the shape of the projected image 4s. This configuration suppresses a decrease in the amount of light Li incident from the light incident section 1, and allows the light detection section 6 to detect light Lr that passes through the second light passing section 41 with high efficiency. As a result, in this embodiment, the light utilization efficiency of the spectrometer 10 can be improved, and the spectroscopic accuracy of the spectrometer 10 can be improved.

In addition, in this embodiment, the first light passing portion 11 and the second light passing portion 41 are in a conjugate relationship for light of a predetermined wavelength within the range of wavelengths λm and λM. As the tilt of the reflecting surface 32 of the movable light reflecting portion 3 changes, the focal position of light reaching the light emitting portion 4 changes depending on its wavelength, which may result in a decrease in wavelength resolution. In this embodiment, by making the first light passing portion 11 and the second light passing portion 41 conjugate with each other for light of a predetermined wavelength, the amount of change in focal position for light of the predetermined wavelength can be suppressed, and a decrease in wavelength resolution can be suppressed.

When the first light passing section 11 and the second light passing section 41 are formed in a slit shape, the focal position tends to change in the normal direction of the first light passing section 11 and the second light passing section 41 due to aberration as the distance from the center in the longitudinal direction of the slit increases. For this reason, it is preferable to make the shape of the concave diffraction grating 2 aspherical, thereby establishing a conjugate relationship between the first light passing section 11 and the second light passing section 41.

[Third embodiment]
Next, a third embodiment of the spectroscope 10 will be described.

Figure 12 is a cross-sectional view illustrating the configuration of the light incident section 1 and light exit section 4 according to this embodiment. Note that since the light incident section 1 and light exit section 4 have the same configuration, the same reference numerals are used in Figure 12. This also applies to Figures 13 and 14 below.

As shown in FIG. 12, the light incident portion 1 includes a nickel (Ni) substrate 111, a black chromium (Cr) film 112, and a first light passing portion 11.

The black chrome film 112 is laminated on the surface of the nickel substrate 111 corresponding to the inside of the spectrometer 10, and constitutes the first non-light-transmitting section 12. The first light-transmitting section 11 is formed to penetrate the nickel substrate 111 and the black chrome film 112.

The light emitting section 4 includes a nickel substrate 411, a black chrome film 412, and a second light passing section 41.

The black chrome film 412 is laminated on the surface of the nickel substrate 411 that corresponds to the inside of the spectrometer 10, and forms the second non-light-transmitting portion 42. The second light-transmitting portion 41 is formed to penetrate the nickel substrate 411 and the black chrome film 412.

The light input section 1 and the light output section 4 are each formed using the electroforming process. Electroforming is a processing method in which metal ions are electrodeposited onto a base material to form a shape. The light input section 1 and the light output section 4 are formed by electrodepositing chromium metal ions onto a nickel substrate, which serves as the base material.

By forming the light incident section 1 and light exit section 4 using an electroforming process, the light incident section 1 and light exit section 4 can be made thin. As a result, in this embodiment, light reflection on the inner walls of the first light passing section 11 and second light passing section 41 can be reduced, and stray light can be suppressed.

Nickel is an ideal material for the substrates of the light input section 1 and light output section 4 because it is easy to process using electroforming.

Constructing the substrates of the light entrance section 1 and light exit section 4 using black nickel materials such as tin-nickel alloy, nickel-zinc alloy, or tin-nickel-copper alloy reduces the reflectance of the light entrance section 1 and light exit section 4, and reduces reflections on the inner walls of the first light passing section 11 and second light passing section 41, for example. This suppresses stray light in the spectrometer 10.

Since the light incident portion 1 includes the black chrome film 112 and the light exit portion 4 includes the black chrome film 412, when multiple reflections occur between the light incident portion 1 and the light exit portion 4, the multiple reflected light is extinguished as the number of multiple reflections increases. This makes it possible to suppress stray light caused by multiple reflected light.

Figure 13 is a cross-sectional view illustrating the configuration of the light incident section 1a and light exit section 4a according to the first modified example.

As shown in FIG. 13, the light incident portion 1a includes a silicon (Si) substrate 111a, a vacuum-deposited light-shielding film 112a, and a first light passing portion 11.

The vacuum-deposited light-shielding film 112a is laminated on the surface of the silicon substrate 111a corresponding to the inside of the spectrometer 10, and forms the first non-light-transmitting section 12. The first light-transmitting section 11 is formed to penetrate the silicon substrate 111a and the vacuum-deposited light-shielding film 112a.

The light emitting section 4a includes a silicon substrate 411a, a vacuum-deposited light-shielding film 412a, and a second light passing section 41.

The vacuum-deposited light-shielding film 412a is laminated on the surface of the silicon substrate 411a corresponding to the inside of the spectrometer 10, and constitutes the second non-light-transmitting section 42. The second light-transmitting section 41 is formed to penetrate the silicon substrate 411a and the vacuum-deposited light-shielding film 412a.

The vacuum-deposited light-shielding films 112a and 412a are each an example of a first reflective film, and are low-reflection films with low reflectivity. The low-reflection film can be a granular metal film or the like that can be formed by vacuum deposition or plating.

By including the silicon substrate 411a in the light input section 1a and the light output section 4a, the light input section 1a and the light output section 4a can be manufactured with high precision and low cost using semiconductor processes, MEMS processes, etc. Other effects are the same as those of the light input section 1 and the light output section 4.

Figure 14 is a cross-sectional view illustrating the configuration of the light input section 1b and the light output section 4b according to the second modified example.

As shown in FIG. 14, the light incident portion 1b includes a glass substrate 111b, a chromium/chromium oxide film 112b, and a first light passing portion 11.

The chromium/chromium oxide film 112b is laminated on the surface of the glass substrate 111b corresponding to the inside of the spectrometer 10, and constitutes the first non-light-transmitting portion 12. The first light-transmitting portion 11 is formed to penetrate the chromium/chromium oxide film 112b.

The light emitting portion 4b includes a glass substrate 411b, a chromium/chromium oxide film 412b, and a second light passing portion 41.

The chromium/chromium oxide film 412b is laminated on the surface of the glass substrate 411b corresponding to the inside of the spectrometer 10, and forms the second non-light-transmitting portion 42. The second light-transmitting portion 41 is formed to penetrate the chromium/chromium oxide film 412b.

The chromium/chromium oxide films 112b and 412b are examples of second reflective films, and are low-reflection films with low reflectivity. The low-reflection film can be a granular metal film that can be formed by vacuum deposition or plating. The low-reflection film can also be formed from an alternating laminate film of chromium film and silicon oxide film, or chromium film and chromium oxide film, etc.

By using glass substrates, the light entrance portion 1b and light exit portion 4b can be manufactured inexpensively. Furthermore, by forming the first non-light-transmitting portion 12 and the second non-light-transmitting portion 42 using a multi-layer laminate of dielectric thin films, the light transmission characteristics of the light entrance portion 1b and light exit portion 4b can be adjusted, reducing stray light. Other effects are similar to those of the light entrance portion 1 and light exit portion 4.

In this embodiment, any of light incident sections 1, 1a, and 1b may be used as the light incident section, and any of light output sections 4, 4a, and 4b may be used as the light output section. Light incident sections 1, 1a, and 1b may be used in combination with light output sections 4, 4a, and 4b as appropriate.

In the following explanation, light entrance section 1 and light exit section 4 are used as examples, but they can also be replaced with light entrance section 1a or 1b, or light exit section 4a or 4b.

Here, Figure 15 is a diagram explaining the reflected light intensity at the first non-light-passing portion 12 and the second non-light-passing portion 42. The horizontal axis of Figure 15 represents the normalized tilt of the reflecting surface 32, and the vertical axis represents the normalized amount of light received at the light detection unit 6.

In Figure 15, solid line graph 151 represents the light intensity received by the light detection unit 6 of the main light. Dashed line graph 152 represents the light intensity received by the light detection unit 6 of light that has made one round trip by multiple reflection between the light entrance unit 1, where the reflectance of the first non-light-passing portion 12 is 90%, and the light exit unit 4, where the reflectance of the second non-light-passing portion 42 is 90% (referred to as single-round trip light).

The dashed-dotted line graph 153 represents the light intensity received by the light detection unit 6 after light has traveled back and forth once due to multiple reflections between the light entrance unit 1, where the reflectance of the first non-light-transmitting portion 12 is 50%, and the light exit unit 4, where the reflectance of the second non-light-transmitting portion 42 is 50%.

The dashed-dotted line graph 153 represents the intensity of light received by the light detection unit 6 after multiple reflections that make a round trip between the light entrance unit 1, where the reflectance of the first non-light-transmitting portion 12 is 30%, and the light exit unit 4, where the reflectance of the second non-light-transmitting portion 42 is 30%.

The main light and the one-time round trip light are light of a predetermined wavelength within the range between wavelengths λm and λM.

The one-time round trip light is stray light because it is detected by the light detection unit 6 after being reflected by the reflecting surface 32 at an angle different from the appropriate angle. The relative intensity of the one-time round trip light to the main light is 0.35 in graph 151, 0.11 in graph 152, and 0.04 in graph 153.

For example, in applications where the material of a substance is determined from its spectral reflectance using the spectroscope 10, determination is possible if the stray light relative to the main light is approximately 5% or less. Therefore, based on Figure 15, it is preferable that the reflectance of both the first non-light-passing portion 12 and the second non-light-passing portion 42 be 30% or less for light of a specified wavelength within the range of wavelengths λm and λM. By doing so, the light intensity of the light that makes a single round trip detected by the light detection unit 6 can be reduced to 5% or less, ensuring high spectroscopic accuracy using the spectroscope 10.

Figure 16 is a diagram explaining reflections on the inner walls of the first light passing section 11 and the second light passing section 41. Figure 16 shows an enlarged view of the first light passing section 11 in the light incident section 1 and the second light passing section 41 in the light exit section 4.

In Figure 16, inner wall 13 represents the inner wall of the first light passing section 11, and inner wall 44 represents the inner wall of the second light passing section 41. Thickness t represents the thickness of each of the first light passing section 11 and the second light passing section 41.

Light reflected by the inner walls 13 and 44 becomes stray light because it is reflected in areas other than the effective area of the concave diffraction grating 2. If the thickness t of each of the first light passing section 11 and the second light passing section 41 is 0.1 mm or less, the intensity of the light reflected by the inner walls 13 and 44 will be sufficiently small compared to the intensity of the light used for spectroscopic analysis, ensuring high spectroscopic accuracy by the spectrometer 10.

Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as set forth in the claims.

The spectrometer according to the embodiment can also be used in an analytical device. Such an analytical device can identify the resin type of an object by spectroscopically analyzing the spectrum obtained by the spectrometer, and can then sort and recover the object by resin type as a recyclable material.

1. Light incident section (an example of light incident means)
1s Projected image 11 First light passing portion 12 First non-light passing portion 13 Inner wall 2 Concave diffraction grating (an example of a diffraction grating)
3. Movable light reflecting portion (an example of reflecting means)
31: Oscillating shaft 32: Reflecting surface 33: Reflecting line 4: Light emitting portion (an example of a light emitting means)
4s Projected image 41 Second light-passing portion 42 Second non-light-passing portion 43 Emission line 44 Inner wall 5 Substrate 6 Light detection portion (an example of a light detection means)
60 Light receiving central axis 61 Light receiving window 10 Spectrometer 15 Reflecting member 112a, 412a Vacuum deposition light blocking film (an example of a first reflecting film)
112b, 412b: Chromium/chromium oxide film (an example of a second reflective film)
151, 152, 153 Graph 411 Nickel substrate 411a Silicon substrate 411b Glass substrate Li, Lr, Lm, LM Light Li0, Lr0 Chief ray Lr1, Lm1, LM1 Optical axis Ld Wavelength dispersed light θr, θm, θM Incident angle λr, λm, λM Wavelength Pi, Pr Surface t Thickness

Patent No. 5558927

Claims (11)

a light incidence means for allowing external light to be incident through the first light passing portion;
a diffraction grating that wavelength-disperses the light incident by the light incident means;
a reflecting means having a reflecting surface that reflects wavelength-dispersed light caused by the diffraction grating, the inclination of the reflecting surface being variable;
a light output unit that outputs a part of the light of different wavelengths included in the wavelength-dispersed light reflected by the reflecting unit to the outside through a second light passing portion,
A spectrometer that satisfies the conditions of the following expressions (1) and (2):
|θr|<|θm| ...(1)
|θr|<|θM| ...(2)
(λm represents the minimum wavelength in the wavelength-dispersed light, λM represents the maximum wavelength in the wavelength-dispersed light, λr represents a wavelength selected from the range between λm and λM among the different wavelengths in the wavelength-dispersed light, θm represents the angle of incidence at which light of wavelength λm is incident on the second light passing portion, θM represents the angle of incidence at which light of wavelength λM is incident on the second light passing portion, and θr represents the angle of incidence at which light of wavelength λr is incident on the second light passing portion.) further comprising a light detection means for detecting light emitted from the light emitting means,
the light detection means is provided so as to be in contact with or in close proximity to the light emitting means;
10. The spectrometer of claim 1. The spectrometer of claim 2, wherein the light detection means supports the light emission means. A spectrometer according to any one of claims 1 to 3, wherein the shape of the projected image of the first light passing portion projected onto a plane perpendicular to the chief ray of the light passing through the first light passing portion is equal to the shape of the projected image of the second light passing portion projected onto a plane perpendicular to the chief ray of the light emitted from the light emitting means. A spectrometer according to any one of claims 1 to 4, wherein the first light passing section and the second light passing section are in a conjugate relationship with respect to light of a predetermined wavelength within the range between wavelengths λm and λM. A spectrometer as described in any one of claims 1 to 5, wherein the reflectance of the first non-light-passing portion of the light input means and the reflectance of the second non-light-passing portion of the light output means are both 30% or less for light of a predetermined wavelength within the range of wavelengths λm and λM. A spectroscope according to any one of claims 1 to 6, wherein the thickness of each of the first light passing section and the second light passing section is 0.1 mm or less. A spectrometer according to any one of claims 1 to 7, wherein the light input means and the light output means are each formed by an electroforming process. A spectrometer according to any one of claims 1 to 7, wherein the light input means and the light output means each include a silicon substrate and a first reflective film formed on the silicon substrate. A spectrometer according to any one of claims 1 to 7, wherein the light input means and the light output means each include a glass substrate and a second reflective film formed on the glass substrate. An analytical device having a spectrometer according to any one of claims 1 to 10.