JP2001235368A - Micro spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and cost of spectrometer without requiring many light receiving elements. SOLUTION: This micro spectrometer is provided with a light entering part 2, a diffraction grating part 3 for diffracting light from the light entering part 2, and a light receiving part 5 for receiving diffracted light diffracted by the diffraction grating part 3. The light entering part 2 and the diffraction grating part 3 are integrally formed on a base, and the light receiving part 5 is made freely movable along an imaging part of the diffracted light. A spectrum can be measured with a small number of the light receiving elements. Or, a second light entering part 22 where a reference light out of a wavelength range for a measuring object enters is provided, and a second light receiving element for receiving the reference light of different spectral sensitivity wavelength from the light receiving element for receiving light from the measuring object is installed in the light receiving part 5. A shift of an imaging position can be corrected by using an output of the second light receiving element for receiving the reference light even when the imaging position of the diffracted light is shifted due to an individual difference of width of grating of the diffraction grating part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microspectrometer for calculating a spectral intensity distribution by decomposing light for each wavelength.

[0002]

2. Description of the Related Art FIG.
As shown in FIG. 2, a light incident portion 2 fixing an end of the optical fiber 20, a diffraction grating portion 3 provided with a grating 30 for diffracting light incident through the optical fiber 20, a mirror 4 and the like are provided. There is a type integrally formed with the base 1 to which a light receiving unit 5 for receiving light diffracted for each wavelength is attached. Here, a photodiode array in which a large number of light receiving elements are arranged at equal intervals is used for the light receiving section 5, and each light receiving element is positioned so as to coincide with the image forming section of each wavelength and is adhered and fixed to the base 1. By doing so, light of each wavelength diffracted by the diffraction grating section 3 can be received by each light receiving element.

[0003]

However, the light receiving section 5 composed of a photodiode array is extremely expensive.
Even if the light-entering portion and the diffraction grating portion are integrated on the base, the molding can be performed at low cost, but the overall price jumps. 2 for receiving the diffracted light of the visible region light (VIS)
The 56-element Si photodiode array costs several hundred thousand yen, and the InGaAs or Ge photodiode array for receiving diffracted light of near-infrared light (NIR) costs several hundred thousand yen.

[0004] The present invention has been made in view of the above points, and an object of the present invention is to provide a small and inexpensive microspectrometer.

[0005]

Means for Solving the Problems A first feature of the present invention is that a light incident portion, a diffraction grating portion for diffracting the light from the light incident portion, and a device for receiving the diffracted light by the diffraction grating portion. In a microspectrometer including a light receiving portion, a light incident portion and a diffraction grating portion are integrally formed on a base, and the light receiving portion is movable along an image forming portion of the diffracted light. Is to be. Spectrum measurement can be performed with a small number of light receiving elements.

A second feature of the present invention is that
A light incident portion, a diffraction grating portion for diffracting light from the light incident portion,
A light receiving portion movable along an image forming portion of the diffracted light by the diffraction grating portion, wherein the second input portion receives the reference light having a wavelength outside the wavelength range to be measured. The second light receiving portion, which has a light portion and is movable along the image forming portion of the diffracted light, is for receiving the reference light and has a different spectral sensitivity wavelength from the light receiving element for the light to be measured. That the device is provided. In this device, even when the imaging position of the diffracted light shifts due to the individual difference in the grating width of the diffraction grating portion, the correction of the imaging position shift is performed by using the output of the second light receiving element that receives the reference light. It can be carried out. It should be noted that the second light incident section may be replaced by a light incident section. In other words, the reference light having a wavelength different from the wavelength range of the light to be measured may be combined with the light to be measured and sent from the light incident portion.

[0007] One of the at least two light receiving elements having different spectral sensitivity wavelengths provided in the light receiving section is an InGaAs element, and one of the at least two light receiving elements having different spectral sensitivity wavelengths provided in the light receiving section is Si. It is preferably an element.

A light receiving portion may face the other end of the waveguide whose one end is located at the image forming position of the diffracted light, and the light receiving portion may receive the diffracted light via the waveguide. The other end of the waveguide may be positioned on the circumference so that the light receiving unit positioned on the rotating body is movable along the other end of the waveguide by rotation of the rotating body.

[0009] In addition to measuring the spectrum distribution based on the relationship between the moving time of the light receiving unit and the output signal from the light receiving unit, a measuring unit for measuring the moving time of the light receiving unit is provided. The spectral distribution may be measured from the relationship between the position of the light receiving unit moved by the detection member and the output signal from the light receiving unit.

It is also preferable to measure the spectral distribution by repeating the movement of the light receiving section a plurality of times.

Regarding the point of moving the light receiving portion, the light receiving portion is moved in the axial direction of the screw shaft by being screwed with the screw shaft which is driven to rotate around the axis, or on a rack which is engaged with the pinion which is driven to rotate. A light receiving part is provided on the actuator, and a light receiving part is provided on an actuator driven by air pressure or spring pressure to make it movable, or on a cam follower that reciprocates by engaging with a rotationally driven cam. It can be provided to be movable. Also, the light receiving unit is moved by using the bimetal and the heater for heating the bimetal as a driving source,
The light receiving unit may be moved using the shape memory alloy and a heater for heating the shape memory alloy as a drive source.

Further, the light receiving section may be moved by electromagnetic driving means.

It is also preferable that the light receiving section is movable by a support member integrally provided on a base on which the light input section and the diffraction grating section are integrally formed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to an example of an embodiment. The microspectrometer shown in the figure is a light-incoming unit 2 for fixing an end of an optical fiber 20.
And a diffraction grating section 3 provided with a grating for diffracting light incident through an optical fiber 20, and a Fastie-Ebert type in which a mirror 4 and the like are integrally formed on the base 1, and a light receiving section 5 is attached. However, the light receiving section 5 here is freely movable along the image forming position of the diffracted light, and the light receiving element 51 has only a small number (one in the illustrated example).

The light to be measured is sent to the optical fiber 20 of the light input section 2 and is reflected by the mirror 4, then diffracted by the diffraction grating section 3, and the diffracted light is reflected by the mirror 4 again to move the light receiving section 4. The light is sent to the free imaging position, but the resolution of the measurement data is adjusted by moving the light receiving unit 5 along the imaging position of the diffracted light and adjusting the speed of this movement and the data sampling time. It is something that can be done.

In the mass production of the base 1 in which the light incident portion 2 and the diffraction grating portion 3 are integrated, a change in the shrinkage rate due to a slight change in the molding conditions at the time of molding the base 1 is caused by the change in the diffraction grating portion. Influence on the grating width of the diffraction grating No. 3 to cause an image not to be formed at a position according to the optical design. In the case where the light receiving unit 5 reciprocates along the image forming part of the diffracted light, that is, on the assumption that the image forming part is located at the position according to the optical design, there is an individual difference and a quality variation occurs. . FIG. 2 shows an example that addresses this point.

The micro-spectrometer shown here is a light-entering section 2 for fixing the end of the optical fiber 20.
And the second fixing the end of the optical fiber 21
A light input part 22, a diffraction grating part 3 provided with a grating for diffracting light incident through the optical fibers 20, 21 and a mirror 4 and the like are integrally formed on the base 1.
The light receiving unit 5 is attached thereto. The light receiving unit 5 includes at least two light receiving elements 51 and 52 having different spectral sensitivity wavelength ranges, and is movable along an image forming position of the diffracted light. .

The two types of light receiving elements 51 and 52 of the light receiving section 5
Has a different spectral sensitivity wavelength range as described above. For example, as shown in FIG. 3, the light receiving element 51 has sensitivity in a visible light region made of an Si element, and the other light receiving element 52 is made of an InGaAs element. It has sensitivity in the near infrared light region. When the wavelength range of the light to be measured is in the near-infrared light range of 1200 nm to 1800 nm, the light receiving element 52 is used for the light to be measured and the light receiving element 51 is used for the reference light.

On the other hand, the light to be measured is sent to the optical fiber 20 of the light entering section 2 and is reflected by the mirror 4, then diffracted by the diffraction grating section 3, and the diffracted light is reflected by the mirror 4 again to receive light. The reference light 4 is sent to the movable imaging position where the reference light 4 is sent to the optical fiber 21 of the second light input unit 22. As the reference light, visible light to which the light receiving element 51 has sensitivity is used. In addition, as visible light,
Those having an emission line spectrum are preferred.

If the light receiving unit 5 is moved along the imaging position of the diffracted light while the light to be measured is sent from the light input unit 2 and the reference light is sent from the light input unit 22, the time axis of the movement or For example, outputs as shown in FIG. 4 can be obtained from the light receiving elements 51 and 52 according to the position axis. Therefore, if the correlation between the light receiving element 51 that receives the reference light and the light receiving element 52 that receives the light to be measured is calculated in advance with respect to the image forming position of the diffracted light, the grating width of the diffraction grating unit 3 becomes larger. Even if it changes, it can be easily corrected. The start and end of the measurement can be performed by using the output of the light receiving element 51 receiving the reference light as a trigger. Light receiving element 5
It goes without saying that a plurality of pairs of 1 and the light receiving element 52 may be provided.

As the light receiving element 52 for the near-infrared light region, since it has good sensitivity characteristics in this region and can be operated at room temperature, it can be used to analyze organic substances having a large absorption in the near-infrared light region. Although a preferred InGaAs device has been shown, it does not prevent other devices from being used.

Further, as the light receiving element 51 in the visible light region, a Si device which has good sensitivity characteristics in this region, can be operated at room temperature, and easily produces a bright line spectrum has been described. It does not prevent using other elements.

FIG. 5 shows another example. This means that the other end of each of the waveguides 7 composed of a plurality of optical fibers whose one end is located at the image forming position of the diffracted light is arranged in a straight line, and the light receiving unit 5 is movable along the other end of the waveguides 7. This is shown. This is particularly effective when the imaging position is not on a straight line due to the optical system. For example, as shown in FIG. 6, in the case of a Rowland mount using a concave diffraction grating as the diffraction grating section 3, the diffracted light is in a Rowland mount.
If an attempt is made to move the light receiving unit 5 along the circle without any positional deviation to form an image on the circle d, the moving structure becomes complicated. Are arranged on the above-mentioned circle, which is an image forming position, and the other end is arranged in a straight line, so that the light receiving section 5 only needs to be moved linearly, and the configuration of the drive mechanism for moving the light receiving section 5 is simplified, and Measurement accuracy is also improved.

The other ends of the waveguides 7 are not arranged in a straight line, but are arranged in a circle as shown in FIG. 7, and the light receiving section 5 is arranged on a rotating body 70 and guided by the rotation of the rotating body 70. The wave path 7 may be freely movable along the circle at the other end. In this case, the driving mechanism for moving the light receiving unit 5 can be simplified.

As described above, when the spectrum is measured from the outputs of the light receiving elements 51 and 52, the measurement is performed based on the time axis or the position axis of the movement of the light receiving section 5. It is preferable to provide a measuring unit for measuring the moving time of the light receiving unit 5 and measure the spectrum distribution from the relationship between the time axis and the output signal as shown in FIG. High measurement accuracy can be obtained.

However, when the moving speed of the light receiving unit 5 is not constant, a detecting member 8 for detecting the moving position of the light receiving unit 5, for example, a laser displacement sensor is provided as shown in FIG. The spectrum distribution can be measured from the relationship between the (moving distance) and the output signal. Since it is not necessary to move the light receiving unit 5 at a constant speed, the configuration of the driving unit can be simplified.

Further, when performing the spectrum measurement, particularly when the measurement is performed based on the position axis, FIG.
As shown in (5), the measurement accuracy can be improved by performing the measurement on both the outward path and the return path of the movement of the light receiving unit 5, taking an average value of a plurality of measurement results, and using this as a measured value.

FIG. 11 shows a specific example of the configuration of a drive unit for moving the light receiving unit 5. A slider 55 slidably guided by a screw shaft 53 driven by a motor 54 is screwed into the screw shaft 53. The light receiving unit 5 is arranged on a slider 55 that moves in the axial direction of the screw shaft 53 by the rotation of the screw shaft 53. In this case, management of the moving speed of the light receiving unit 5 is easy.

As shown in FIG. 12, even if the light receiving section 5 is provided on the rack 61 which meshes with the pinion 60 which is driven to rotate, the light receiving section 5 can be linearly moved easily and accurately.

As shown in FIG.
The light receiving unit 5 may be provided on the actuator 63 that is driven by.

Also, as shown in FIG.
The light receiving unit 5 is provided on the actuator 63 to which one end of each of the springs 77 is connected, and the switch 78 to which the other end of the spring 77 is connected is manually pulled to accumulate spring force in the springs 76, 77. By releasing the finger, the light receiving unit 5 may be reciprocated by the spring force of the springs 76 and 77.

When the cam 66 having the eccentric shaft 67 is rotated as shown in FIG.
The light receiving unit 5 may be arranged on the cam follower 67 in the mechanism for linearly reciprocating the cam follower 67 that engages with the lens. Accurate reciprocating linear motion can be obtained.

In addition, as shown in FIG.
The actuator 63 provided with the light receiving unit 5 is driven by the bimetal 71 expanded by heating by the heater 5, or the actuator provided by the shape memory alloy 72 expanded by heating by the heater 75 as shown in FIG. In the one that drives 63, the light receiving section 5 can be moved only by adjusting the temperature.

FIG. 18 shows an example in which the light receiving section 5 can be moved by electromagnetic driving. A conductor section 57 is provided between a pair of permanent magnets 56 provided on the light receiving section 5 and having mutually opposite polarities. The conductor portion 57 is slidably contacted with two metal bars 58, 58 arranged in parallel with each other, and the two metal bars 58, 58 and the metal bars 58, 58 are arranged.
By passing a current through the conductor portion 57 that short-circuits between 58,
The light receiving unit 5 is moved by electromagnetic force in the longitudinal direction of the metal bar 58. The direction in which the light receiving section 5 is moved can be switched by the switch 59.

Further, as shown in FIG. 19, a hinge spring 15 may be formed integrally with the base 1, and the light receiving section 5 may be attached to the tip of the hinge spring 15. In addition,
The bending of the hinge spring 15 is manually performed, and the light receiving unit 5 is reciprocated by the spring force of the hinge spring 15. This eliminates the need to separately prepare a member for reciprocating the light receiving unit 5. At this time, the light receiving unit 5 draws an arc-shaped trajectory, but by calculating and processing the angle and curvature of the curved surface of the mirror 4 by optical design, light can be imaged on the arc-shaped trajectory. To be able to do. The above-described waveguide 7 made of an optical fiber may be used in combination.

[0036]

As described above, according to the present invention, a micro unit including a light incident portion, a diffraction grating portion for diffracting light from the light incident portion, and a light receiving portion for receiving light diffracted by the diffraction grating portion is provided. In the spectrometer, the light incident part and the diffraction grating part are integrally formed on the base, and the light receiving part is movable along the image forming part of the diffracted light. It can perform spectrum measurement,
In addition to being compact and inexpensive at the same time as being integrated, the measurement resolution can be adjusted by adjusting the sampling interval.

Further, a micro-device comprising a light incident portion, a diffraction grating portion for diffracting the light from the light incident portion, and a light receiving portion movable along an image forming portion of the diffracted light by the diffraction grating portion. The spectrometer includes a second light incident portion for receiving a reference light having a wavelength outside the wavelength region to be measured, and a light receiving portion movable along an image forming portion of the diffracted light includes a reference light. In the case of a light receiving device having a second light receiving device having a different spectral sensitivity wavelength from the light receiving device for the light to be measured, the imaging position of the diffracted light is shifted due to the individual difference in the grating width of the diffraction grating portion. Even by using the output of the second light receiving element that receives the reference light, it is possible to easily correct the deviation of the imaging position, and therefore, the light receiving unit is configured with a small number of light receiving elements. Can be provided at a low cost Can be performed calculation of the precise spectral distribution, or even those that can also be adjusted measurement resolution in the adjustment of the sampling interval.

In the case where the reference light is used, one of the at least two light receiving elements having different spectral sensitivity wavelengths provided in the light receiving section is an InGaAs element, or at least one having a different spectral sensitivity wavelength provided in the light receiving section. It is preferable that one of the two light receiving elements is a Si element in terms of measurement at normal temperature and sensitivity.

Further, if the light receiving portion is opposed to the other end of the waveguide whose one end is located at the image forming position of the diffracted light and the light receiving portion receives the diffracted light via the waveguide, the measurement accuracy can be improved. And the configuration of the driving unit for moving the light receiving unit can be simplified. In particular, the light receiving unit positioned on the rotating body by positioning the other end of the waveguide on the circumference. If the portion can be moved along the other end of the waveguide by the rotation of the rotating body, a device that can move the light receiving portion at a constant speed can be easily obtained.

A measuring unit for measuring the moving time of the light receiving unit is provided, and the measurement accuracy can be improved by measuring the spectrum distribution from the relationship between the moving time of the light receiving unit and the output signal from the light receiving unit. There is also provided a detecting member for detecting the moving position of the light receiving unit, and for measuring the spectral distribution from the relationship between the moving position of the light receiving unit by the detecting member and the output signal from the light receiving unit, to move the light receiving unit. The configuration of the driving unit can be simplified.

Further, if the spectrum distribution is measured by repeating the movement of the light receiving section a plurality of times, reproducibility can be confirmed.

The light receiving portion is adapted to move in the axial direction of the screw shaft by screwing with a screw shaft driven to rotate around the axis, or to provide a light receiving portion on a rack meshed with a pinion driven to rotate. Light-receiving unit on an actuator driven by air pressure or spring pressure, or movable on a cam follower that reciprocates by engaging with a cam driven by rotation. By doing so, the configuration for moving can be simplified, and an inexpensive device can be obtained.

When the light receiving section is moved by using the bimetal and the heater for heating the bimetal as a driving source, or when the light receiving section is moved by using the shape memory alloy and the heater for heating the bimetal and the heater for heating the same, It is possible to obtain a device that can move the light receiving unit only by adjusting the temperature.

Further, the structure of the drive section can be simplified even if the movable section is made movable by the electromagnetic drive means.

Further, if the light receiving portion is made movable by a support member integrally provided on a base on which the light incident portion and the diffraction grating portion are integrally formed, the number of members for supporting the light receiving portion can be reduced. Therefore, productivity can be increased and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an example of an embodiment of the present invention.

FIG. 2 is a schematic perspective view of another example of the embodiment of the present invention.

FIG. 3 is a sensitivity characteristic diagram of two light receiving elements of the above.

FIG. 4 is an explanatory diagram of outputs of two light receiving elements according to the first embodiment.

FIG. 5 is a schematic perspective view of still another example.

FIG. 6 is a schematic plan view of another example.

FIG. 7 is a schematic perspective view of still another example.

FIG. 8 is an operation explanatory view of the above.

FIG. 9 is an operation explanatory diagram of another example of the above.

FIG. 10 is an operation explanatory diagram of still another example of the above.

FIG. 11 is a schematic perspective view of an example of a movement driving unit.

FIG. 12 is a schematic perspective view of another example of the movement driving means.

FIGS. 13A and 13B are schematic perspective views of still another example of the movement driving means.

FIG. 14 is a schematic perspective view of another example of the movement driving means.

FIG. 15 is a schematic perspective view of still another example of the movement driving means.

FIG. 16 is a side view of another example of the movement driving means.

FIG. 17 is a side view of still another example of the movement driving means.

FIG. 18 is a schematic perspective view of another example of the movement driving means.

FIG. 19 is a schematic perspective view of still another example of the movement driving means.

FIG. 20 shows a conventional example, where (a) is a schematic perspective view and (b)
FIG. 4 is a perspective view of a diffraction grating portion.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base 2 light incident part 3 diffraction grating part 5 light receiving part 22 second light incident part

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Yoshida 1048 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Works, Ltd. (reference) 2G020 AA03 AA04 CB42 CB43 CC04 CC63 CD03 CD04 CD24 CD39 CD57 2H037 AA04 BA01 BA11 CA33

Claims (18)

[Claims] 1. A microspectrometer comprising: a light incident portion; a diffraction grating portion for diffracting light from the light incident portion; and a light receiving portion for receiving light diffracted by the diffraction grating portion.
A microspectrometer, wherein a light incident portion and a diffraction grating portion are integrally formed on a base, and a light receiving portion is movable along an image forming portion of diffracted light. 2. A micro-computer comprising: a light incident portion; a diffraction grating portion for diffracting the light from the light incident portion; and a light receiving portion movable along an image forming portion of the diffracted light by the diffraction grating portion. In the spectrometer, while having a second light input section for receiving the reference light of a wavelength outside the wavelength range to be measured,
The light receiving portion movable along the image forming portion of the diffracted light is provided with a second light receiving device for receiving the reference light and having a different spectral sensitivity wavelength from the light receiving device for the light to be measured. A microspectrometer characterized by the following. 3. The microspectrometer according to claim 2, wherein one of the at least two light receiving elements provided with the light receiving portions and having different spectral sensitivity wavelengths is an InGaAs element. 4. The microspectrometer according to claim 2, wherein one of at least two light receiving elements of the light receiving section having different spectral sensitivity wavelengths is an Si element. 5. A light-receiving portion facing one end of a waveguide whose one end is located at an image forming position of the diffracted light, and the light-receiving portion receives the diffracted light via the waveguide. Claim 1
5. The microspectrometer according to any one of the items 4 to 4. 6. The other end of the waveguide is located on a circumference,
6. The microspectrometer according to claim 5, wherein the light receiving section is located on the rotating body and is movable along the other end of the waveguide by rotation of the rotating body. 7. The apparatus according to claim 1, further comprising a measuring unit for measuring a moving time of the light receiving unit, wherein a spectrum distribution is measured from a relationship between a moving time of the light receiving unit and an output signal from the light receiving unit.
7. The microspectrometer according to any one of the above items 6. 8. A device for detecting a movement position of a light receiving unit,
The microspectrometer according to any one of claims 1 to 6, wherein a spectrum distribution is measured from a relationship between a movement position of the light receiving unit by the detection member and an output signal from the light receiving unit. 9. The spectrum distribution is measured by repeating the movement of the light receiving section a plurality of times.
The microspectrometer according to any one of the above items. 10. The light receiving section according to claim 1, wherein the light receiving section is movable in the axial direction of the screw shaft by being screwed with a screw shaft that is driven to rotate around the axis. The described microspectrometer. 11. The microspectros according to claim 1, wherein the light receiving section is provided on a rack meshing with a rotatable pinion and is movable. Meter. 12. The microspectrometer according to claim 1, wherein the light receiving section is provided on an actuator driven by air pressure and is movable. 13. The microspectrometer according to claim 1, wherein the light receiving section is provided on an actuator driven by a spring pressure and is movable. 14. A light receiving unit according to claim 1, wherein said light receiving unit is provided on a cam follower which reciprocates by engaging with a rotationally driven cam and is movable. The described microspectrometer. 15. The microspectrometer according to claim 1, wherein the light receiving section is movable using a bimetal and a heater for heating the bimetal as a driving source. 16. The microspectrometer according to claim 1, wherein the light receiving section is movable using a shape memory alloy and a heater for heating the shape memory alloy as a drive source. 17. The microspectrometer according to claim 1, wherein the light receiving section is movable by electromagnetic driving means. 18. The light receiving section according to claim 1, wherein the light receiving section is movable by a support member integrally provided on a base on which the light input section and the diffraction grating section are integrally formed. Micro spectrometer.