WO2021215034A1

WO2021215034A1 - Spectrometry device

Info

Publication number: WO2021215034A1
Application number: PCT/JP2020/041172
Authority: WO
Inventors: 亮二平岡; 善央米澤
Original assignee: 株式会社島津製作所
Priority date: 2020-04-23
Filing date: 2020-11-04
Publication date: 2021-10-28

Abstract

One aspect of a spectrometry device according to the present invention is provided with: a diffraction grating (32) which carries out wavelength dispersion of incident light; a detection unit (4) which detects, directly or via a plurality of optical elements, light which has been subjected to wavelength dispersion by the diffraction grating; and rotation units (305-303) which rotate the diffraction grating (32) or a retention unit (301) that retains the diffraction grating such that the wavelength or range of wavelengths of the light reaching the detection unit changes, and which rotate the diffraction grating or the retention unit up to a prescribed position such that the light propagated towards the diffraction grating is not directed at the detection unit during dark measurement. According to the spectrometry device of the present aspect, the configuration for dark measurement can be simplified to reduce costs and make the device smaller and lighter.

Description

Spectroscopy device

The present invention relates to a spectroscopic measuring device.

In a general spectroscopic measuring device, the light to be measured is introduced into a spectroscope to disperse the wavelength, and the wavelength-dispersed light is introduced into a detector for detection. For example, in a spectroscopic measuring device using a Zellniterner type spectroscope as disclosed in Patent Document 1, the wavelength of light reaching the detector is scanned by rotating the diffraction grating included in the spectroscope. It is possible to obtain a light intensity distribution over a predetermined wavelength range, that is, an optical spectrum.

The detector used for spectroscopic measurement outputs a very small level detection signal, so-called dark current signal, even when no light is incident. Therefore, in order to obtain an accurate optical spectrum, it is necessary to remove the influence of the dark current signal, and it is common to make corrections based on the dark current signal measured without light incident on the detector. .. The measurement of such a dark current signal is called a dark measurement.

As described in Patent Document 2, in many cases, in a conventional spectroscopic measuring device, in order to block the light incident on the detector during dark measurement, from the light source or input end of the light to be measured to the detector. A shutter is provided on the optical path of.

Japanese Unexamined Patent Publication No. 2001-141565 JP-A-2009-115695

Conventionally, the widely used shutter is a mechanical shutter, which requires an electric circuit such as a motor driver or a controller in addition to a motor for moving a movable body which is a shutter body. Providing such parts such as a motor for a shutter only for dark measurement is an obstacle in reducing the cost of the spectroscopic measuring device. In addition, it is necessary to secure a space for arranging the shutter body, the motor, and the like, which is one of the obstacles in reducing the size and weight of the spectroscopic measuring device.

The present invention has been made to solve these problems, and an object of the present invention is spectroscopic measurement capable of simplifying the configuration for dark measurement, reducing the cost, and reducing the size and weight of the device. To provide the device.

One aspect of the spectroscopic measuring apparatus according to the present invention made to solve the above problems is
A diffraction grating that disperses the light to be measured in wavelength,
A detection unit that detects light wavelength-dispersed by the diffraction grating directly or via one or more optical elements.
The light to be measured travels toward the diffraction grating while rotating the diffraction grating or the holding portion holding the diffraction grating so that the wavelength or wavelength range of the light reaching the detection unit changes. A rotating portion that rotates the diffraction grating or the holding portion to a predetermined position so that the light does not face the detecting portion.
Is provided.

When acquiring the spectrum of light given from the outside, the "light to be measured" here is the light itself given from the outside. Further, when the sample is irradiated with the light emitted from the light source and the transmitted light, the reflected light, the scattered light, the fluorescence, etc. from the sample are spectrally measured, the above-mentioned "measured light" is the transmitted light and the reflected light. Light, scattered light, fluorescence, etc. Furthermore, when the light emitted from the light source is dispersed and monochromaticized to irradiate the sample and the transmitted light or reflected light is detected, the above-mentioned "light to be measured" is the light itself emitted from the light source. Is.

In the spectroscopic measuring device of the above aspect according to the present invention, the rotating portion may include a motor, a drive circuit thereof, and the like. Similar to a general spectroscopic measuring device, when scanning a wavelength for spectroscopic measurement, the diffraction grating (or holding portion) is rotated by a rotating portion, so that the diffraction grating with respect to the light incident on the diffraction grating is displayed. The angle of the diffraction grating is changed. In the spectroscopic measuring apparatus of the above aspect according to the present invention, this rotating portion is used for dark measurement in addition to wavelength scanning for normal spectroscopic measurement.

In the spectroscopic measuring apparatus of the above aspect according to the present invention, at the time of dark measurement, the diffraction grating (or holding portion) is rotated by the rotating portion to a predetermined position beyond the rotation range at the time of normal spectroscopic measurement. .. In that state, the light to be measured traveling toward the diffraction grating from the front stage portion of the diffraction grating, for example, a reflecting mirror or a slit, does not hit the diffraction grating or even if it hits the diffraction plane. The diffracted light (wavelength dispersed light) goes in a direction different from that at the time of normal spectroscopic measurement, and finally does not reach the detection unit. That is, the diffraction grating or the holding portion rotated to a predetermined position at the time of dark measurement has a function of blocking the light incident on the detecting portion, similarly to the shutter.

Therefore, according to the spectroscopic measuring apparatus of the above aspect according to the present invention, a shutter for blocking light reaching the detection unit for dark measurement, a drive mechanism such as a motor for operating the shutter, a drive circuit, and the like, etc. It is not necessary to provide an electric circuit exclusively for dark measurement. Therefore, such members and electric circuits can be removed from the conventional spectroscopic measurement device, and the cost of the device can be reduced and the size and weight of the device can be reduced.

The schematic block diagram of the diffraction grating rotating part in the multi-channel spectroscope which is one Embodiment of the spectroscopic measurement apparatus which concerns on this invention. The block diagram of the main part of the multi-channel spectroscope of this embodiment. The figure which shows the structure at the time of dark measurement in the multi-channel spectroscope of this embodiment. The block diagram of the main part of the spectroscope which is another embodiment.

Hereinafter, a multi-channel spectroscope, which is an embodiment of the spectroscopic measuring apparatus according to the present invention, will be described with reference to the attached drawings.

FIG. 2 is a block diagram of a main part of the multi-channel spectroscope of the present embodiment. This figure shows the arrangement of the main optical elements during normal measurement.
This multi-channel spectroscope measures the wavelength distribution of the light intensity of the input light to be measured, that is, the light spectrum, and is an optical input connector 1 for connecting an optical fiber for light input to be measured, an incident optical system. 2. The spectroscopic unit 3 and the detection unit 4 are provided.

The spectroscopic unit 3 is a Zellni-Turner type spectroscope, and includes an incident slit 30, a first concave mirror 31, a diffraction grating 32, and a second concave mirror 33. Further, the detection unit 4 is a linear sensor in which a large number of light receiving elements are arranged in the wavelength dispersion direction so that light in a predetermined wavelength range can be detected all at once.

FIG. 1 is a schematic configuration diagram of a rotating portion that rotates the diffraction grating 32.
As shown in FIG. 1, the flat plate-shaped diffraction grating 32 is held by the holder 301, and the holder 301 is fixed at a predetermined position on the rotary table 300 which is rotationally driven by the motor 303. Under the control signal from the control unit 305, the motor drive unit 304 drives the motor 303, thereby rotating the rotary table 300.

A diffraction grating 32 is attached to the front surface of the holder 301, and an antireflection portion 302 is formed on the back surface of the holder 301. The antireflection portion 302 can be provided, for example, by attaching an antireflection sheet to the member of the holder 301 or forming an antireflection film on the surface of the member of the holder 301.

The control unit 305 can use a computer (including a microcomputer) including a CPU or the like as a hardware resource and perform the following control operations according to the software installed in the computer.

A normal measurement operation in the multi-channel spectroscope of the present embodiment will be described with reference to FIGS. 1 and 2. When measuring the light to be measured, an optical fiber for inputting the light to be measured is connected to the optical input connector 1.
The control unit 305 operates the motor 303 to move the rotary table 300 to a predetermined initial position so that the diffraction surface of the diffraction grating 32 has a predetermined angle with respect to the first concave mirror 31. When the light to be measured such as laser light is introduced into the apparatus through the optical fiber, the light to be measured is collected by the incident optical system 2 and introduced into the spectroscopic unit 3 through the incident slit 30.

The light to be measured hits the first concave mirror 31 in the spectroscopic unit 3, is reflected, and travels toward the diffraction surface of the diffraction grating 32. The light to be measured at this time is substantially parallel light. The light to be measured that hits the diffraction surface of the diffraction grating 32 is wavelength-dispersed and sent to the second concave mirror 33. The wavelength-dispersed light that hits the second concave mirror 33 is reflected while being converged, and reaches each light receiving element of the detection unit 4. Light of different wavelengths reaches each light receiving element of the detection unit 4 within a predetermined wavelength range λ1 to λ2. Each light receiving element outputs a detection signal according to the intensity of the incident light. This detection signal corresponds to the spectrum of light in the wavelength range λ1 to λ2. Therefore, the spectrum of light within that wavelength range can be obtained in real time. The signal processing unit (not shown) stores the detection signal thus obtained by each light receiving element of the detection unit 4. The signal processing unit may be provided in the multi-channel spectroscope or may be externally provided.

When a detection signal in a predetermined wavelength range is obtained with the position (angle) of the diffraction grating 32 fixed, the control unit 305 drives the motor 303 via the motor drive unit 304 and rotates the rotary table 300 by a predetermined angle. Move it. Then, the angle of the diffraction grating 32 with respect to the light to be measured coming from the first concave mirror 31 changes, and the wavelength range of the wavelength-dispersed light sent from the diffraction grating 32 to the second concave mirror 33 changes. Therefore, the detection unit 4 can obtain a detection signal for light in a wavelength range (for example, λ2 to λ3) different from the wavelength range λ1 to λ2.

While rotating the diffraction grating 32 little by little in this way, the acquisition of the detection signal over the predetermined wavelength range obtained by the detection unit 4 is repeated. Thereby, information representing the spectrum of light in a wide wavelength range can be obtained.

The detection signal obtained as described above includes the dark current signal of the linear sensor itself of the detection unit 4. Therefore, it is necessary to measure the dark current signal in order to obtain an accurate optical spectrum. The operation at the time of dark measurement for that purpose will be described with reference to FIG.

At the time of dark measurement, the control unit 305 operates the motor 303 via the motor drive unit 304 so that the antireflection unit 302 on the back side of the holder 301 points to the reflection surface of the first concave mirror 31. Here, as shown in FIG. 3, the rotation angle of the rotary table 300 is determined so that the light to be measured coming from the first concave mirror 31 is incident on the planar antireflection portion 302 at a substantially right angle. As a result, the light to be measured from the first concave mirror 31 toward the diffraction grating 32 hits the antireflection section 302 instead of the diffraction grating, and most of it is absorbed by the antireflection section 302.

The antireflection unit 302 does not always absorb 100% of the incident light, and some of the incident light may be reflected or scattered. In that case, most of the light reflected or scattered by the antireflection unit 302 passes through a path opposite to that of the incident light, returns to the first concave mirror 31, and is reflected in the direction of the incident slit 30. If the light returned to the vicinity of the incident slit 30 hits a part other than the opening (light-shielding portion) of the incident slit 30 and is reflected, it may become stray light and finally reach the detection unit 4. On the other hand, in the multi-channel spectroscope of the present embodiment, the antireflection portion 34 is also provided on the back surface side (opposite side of the incident optical system 2) of the incident slit 30. Therefore, most of the light except the light that returns in the direction of the incident slit 30 and passes through the opening is absorbed by the antireflection portion 34. Thereby, it is possible to substantially prevent the return light from becoming a stray light.

As described above, at the time of dark measurement, the light to be measured traveling from the first concave mirror 31 toward the diffraction grating 32 does not reach the detection unit 4. Further, even a small amount of light to be measured reflected by the antireflection unit 302 is less likely to become stray light. Thereby, in the multi-channel spectroscope of the present embodiment, the dark current signal can be accurately measured at the time of dark measurement, and the optical spectrum of the light to be measured can be accurately obtained.

In the above description, at the time of dark measurement, the light to be measured coming from the first concave mirror 31 is incident on the antireflection portion 302 at a substantially right angle, but the light to be measured coming from the first concave mirror 31 is the second. It suffices if it is possible to avoid heading toward the concave mirror 33 or directly toward the detection unit 4.

Therefore, the angle at which the light to be measured coming from the first concave mirror 31 enters the antireflection portion 302 is not limited to a right angle, and can be appropriately changed within a range satisfying the above conditions. Further, the antireflection unit 302 is not provided on the back surface of the holder 301, and a structure is adopted so that the light to be measured that hits the holder 301 or the diffraction grating 32 does not finally reach the detection unit 4, or the holder 301 or the diffraction grating 32 is diffracted. Control may be performed so that the light to be measured that hits the grating 32 and is reflected does not finally reach the detection unit 4. Specifically, for example, the rotation position of the rotary table 300 may be set so that the light to be measured that hits the back surface of the holder 301 is directed in a direction other than the second concave mirror 33 and the detection unit 4. Further, even if the light to be measured coming from the first concave mirror 31 hits the diffraction grating 32, if it is possible to prevent the diffracted light from heading toward the second concave mirror 33 or directly toward the detection unit 4. , Such a configuration can also be adopted.

Next, a spectroscope according to another embodiment of the spectroscopic measuring apparatus according to the present invention will be described with reference to FIG.
This spectroscope includes an incident slit 50, a concave diffraction grating 52, an exit slit 55, and a detection unit 56. The concave diffraction grating 52 is held by the holder 53, and an antireflection portion 54 is provided on the back surface of the holder 53. Further, an antireflection portion 51 is also provided on the back surface of the incident slit 50.

During normal measurement, the light to be measured introduced through the incident slit 50 hits the diffraction surface of the concave diffraction grating 52, and the wavelength-dispersed light heads toward the exit slit 55. Only light of a specific wavelength passes through the exit slit 55, enters the detection unit 56, and is detected. Similar to the above embodiment, the holder 53 for holding the concave diffraction grating 52 is installed on a rotary table (not shown), and when the rotary table is rotated, the concave diffraction grating 52 rotates and is taken out from the exit slit 55. The wavelength of light changes. That is, wavelength scanning can be performed by rotating the concave diffraction grating 52.

At the time of dark measurement, the rotary table is rotated so that the antireflection portion 54 on the back surface of the holder 53 points toward the incident slit 50 (so that it is at the position of the holder 53A shown by the dotted line in FIG. 4) as in the above embodiment. Let me. As a result, the light to be measured coming from the incident slit 50 hits the antireflection portion 54, and most of it is absorbed. Further, even if a part of the light to be measured is reflected by the antireflection unit 54, most of the reflected light hits the antireflection unit 51 and is absorbed. As a result, even in the spectroscope of this embodiment, the light that reaches the detection unit 56 at the time of dark measurement can be suppressed. It is also clear that this spectroscope is also capable of the various modifications mentioned in the above embodiment.

Further, in the above embodiment, it is assumed that the light introduced through the optical fiber (light to be measured) is detected by wavelength dispersion in the spectroscopic unit, but the absorption spectrum, reflection spectrum, fluorescence spectrum, etc. of the sample can be detected. It is clear that the present invention can also be applied to a spectroscopic measuring device for acquisition. That is, the present invention can be applied to any spectroscopic measuring device provided with a spectroscope including a diffraction grating and having a configuration in which the diffraction grating is rotated for wavelength scanning.

Furthermore, the above-described embodiment is merely an example of the present invention, and points other than the above-mentioned modified examples are included in the claims of the present application even if they are appropriately modified, modified, or added within the scope of the purpose of the present invention. It is clear that.

[Various aspects]
It will be understood by those skilled in the art that the above-described exemplary embodiments are specific examples of the following embodiments.

(Item 1) One aspect of the spectroscopic measuring apparatus according to the present invention is
A diffraction grating that disperses the incident light in wavelength,
A detection unit that detects light wavelength-dispersed by the diffraction grating directly or via one or more optical elements.
The diffraction grating or the holding portion holding the diffraction grating is rotated so that the wavelength or wavelength range of the light reaching the detection unit changes, and the light traveling toward the diffraction grating during dark measurement is detected. A rotating part that rotates the diffraction grating or the holding part to a predetermined position so as not to face the part.
Is provided.

In the spectroscopic measuring apparatus of the above aspect according to the present invention, the function of shading at the time of dark measurement can be realized by utilizing the rotation mechanism and the circuit of the diffraction grating for wavelength scanning. Therefore, according to the spectroscopic measuring apparatus of the above aspect according to the present invention, a shutter for blocking light reaching the detection unit for dark measurement, a drive mechanism such as a motor for operating the shutter, and an electric circuit such as a drive circuit. It is not necessary to provide such as exclusively for dark measurement. Therefore, such members and electric circuits can be removed from the conventional spectroscopic measurement device, and the cost of the device can be reduced and the size and weight of the device can be reduced.

(Item 2) The spectroscopic measurement device according to the first item is a position in the diffraction grating or the holding portion where light reaches when the diffraction grating or the holding portion is rotated to the predetermined position. , An antireflection portion may be provided.

In the spectroscopic measuring device described in item 2, when the rotating portion rotates the diffraction grating (or the holding portion) to a predetermined position during dark measurement, the antireflection portion comes to the position where the light to be measured reaches. The light to be measured is blocked by this antireflection unit, and the light to be measured does not enter the detection unit. According to the spectroscopic measuring apparatus according to the second item, the reflection of the light to be measured traveling toward the diffraction grating can be eliminated or reduced, so that the stray light can be eliminated or suppressed. Thereby, the light incident on the detection unit at the time of dark measurement can be reduced, and the dark current signal can be lowered.

(Item 3) In the spectroscopic measuring apparatus according to the first or second paragraph, light is emitted when the diffraction grating or the holding portion is rotated to the predetermined position in the diffraction grating or the holding portion. The region reached by may be a surface having an angle that reflects the light traveling toward the diffraction grating so as to reverse its path.

According to the spectroscopic measuring apparatus according to the third item, even if there is reflection of the light to be measured traveling toward the diffraction grating, the reflected light returns in the reverse direction of the light path of the incident light, so that other than that. Compared with the case where the light is reflected in the direction, the possibility of reaching the detection unit as stray light can be reduced.

(Item 4) In the spectroscopic measuring apparatus according to the third item, the light reflected by the diffraction grating or the holding portion and returned in a state where the diffraction grating or the holding portion is rotated to the predetermined position is emitted. Antireflections may be provided at least in part of the reachable positions.

According to the spectroscopic measuring apparatus according to the fourth item, the antireflection unit can absorb the light that has returned by substantially reversing the optical path of the incident light to the diffraction grating. Thereby, the possibility that such return light reaches the detection unit as stray light can be further reduced.

(Item 5) Further, the spectroscopic measuring apparatus according to any one of the items 1 to 4 has a Zellnitner type spectroscope in which mirrors are arranged in the front stage and the rear stage of the diffraction grating, respectively. can do.

(Item 6) Further, in the spectroscopic measuring apparatus according to the item 5, the detection unit is an array-type detector that simultaneously detects light in a predetermined wavelength range, and the rotating unit is a rotating unit during normal measurement. By rotating the diffraction grating or the holding unit, it is possible to scan the wavelength range of light detected by the detecting unit.

According to the spectroscopic measuring apparatus according to the fifth and sixth paragraphs, the spectrum of light in a wide wavelength range can be acquired in real time, and the accuracy of the spectrum can be improved by using a highly accurate dark current signal. Can be done.

1 ... Optical input connector 2 ... Incident optical system 3 ... Spectral part 30 ... Incident slit 31 ... First concave mirror 32 ... Diffraction grating 33 ... Second concave mirror 34 ... Antireflection part 300 ... Rotating table 301 ... Holder 302 ... Antireflection part 303 ... Motor 304 ... Motor drive unit 305 ... Control unit 4 ... Detection unit 50 ... Incident slit 51 ... Antireflection unit 52 ... Concave diffraction grating 53 ... Holder 54 ... Antireflection unit 55 ... Exit slit 56 ... Detection unit

Claims

A diffraction grating that disperses the incident light in wavelength,
A detection unit that detects light wavelength-dispersed by the diffraction grating directly or via one or more optical elements.
The diffraction grating or the holding portion holding the diffraction grating is rotated so that the wavelength or wavelength range of the light reaching the detection unit changes, and the light traveling toward the diffraction grating during dark measurement is detected. A rotating portion that rotates the diffraction grating or the holding portion to a predetermined position so as not to face the portion.
A spectroscopic measuring device comprising.
The first aspect of the present invention, wherein the antireflection portion is provided at a position on the diffraction grating or the holding portion where light reaches when the diffraction grating or the holding portion is rotated to the predetermined position. Spectral measuring device.
The region of the diffraction grating or the holding portion where the light reaches when the diffraction grating or the holding portion is rotated to the predetermined position is relative to the light traveling toward the diffraction grating. The spectroscopic measuring apparatus according to claim 1, which is a surface having an angle that reflects the path in a retrograde manner.
With the diffraction grating or the holding portion rotated to the predetermined position, the antireflection portion is provided at least at a part of the positions where the light reflected and returned by the diffraction grating or the holding portion can reach. The spectroscopic measuring apparatus according to claim 3.
The spectroscopic measuring apparatus according to claim 1, further comprising a Zellnitner-type spectroscope in which mirrors are arranged in the front stage and the rear stage of the diffraction grating, respectively.
The detection unit is an array-type detector that simultaneously detects light in a predetermined wavelength range, and the rotating unit rotates the diffraction grating or the holding unit during normal measurement to detect the detection unit. The spectroscopic measuring apparatus according to claim 5, which scans the wavelength range of light detected in.