JPH0786430B2 - Spectrometer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectroscopic measuring instrument for measuring incident light by dividing it into light having a narrow specific wavelength band.

[0002]

2. Description of the Related Art A monochromator is used to obtain light of a narrow specific wavelength band which becomes measurement light from incident light of a wide wavelength band when performing spectroscopic measurement.

A diffraction grating or a prism is used as a spectroscopic element for splitting incident light in a wide wavelength band into light in a narrow specific wavelength band, and changes the angle of the diffractive surface or the incident surface with respect to the incident light. Thereby, the wavelength band of the emitted light is selected.

The spectroscopic measurement involves irradiating the object to be measured with light dispersed by a monochromator to check the reflection characteristics, absorption characteristics or transmission characteristics of the object to be measured in a narrow specific wavelength band. It is roughly divided into two types of measurement for examining the spectral characteristic itself of light incident on the meter.

In a conventional monochromator, a diffraction grating is often used as an optical element for dispersing incident light because it is easy to configure a wavelength scanning mechanism and a wave number scanning mechanism.

When the incident angle to the diffraction grating is i, the diffraction angle is θ, the diffraction order is m, the wavelength is λ, and the groove spacing of the diffraction grating is d, the following formula is established.

Mλ = d (sini ± sin θ) Therefore, as a wavelength scanning mechanism for rotating the diffraction grating, a bar perpendicular to the center of rotation is provided on a rotary table on which the diffraction grating is mounted, and screw feeding or the like is performed. By moving the above-mentioned bar by the linear motion, the linear motion is changed to the si of the rotation of the diffraction grating.
Ne, that is, a sine bar mechanism that is proportional to the wavelength is often used.

As another example of the structure of the wavelength scanning mechanism,
There are sine cam type cams having a special shape and a cam follower that transmits the movement of the cam to a rotary table so that the rotation of the cam is proportional to the wavelength.

In any of these wavelength scanning mechanisms, the number of revolutions of the screw feed or the cam of the special shape can be used for displaying the wavelength, but since the screw feed or the special shape of the cam is rotated. Since the rotation of the motor used for the transmission is decelerated and transmitted to the rotary table, it takes time to rotate the diffraction grating. This does not cause any particular problem when simply performing the spectroscopy, but when investigating the spectral characteristics of the incident light, the wavelength component of the incident light may change before the rotation of the diffraction grating ends, which causes a problem. Become.

As a spectroscopic measurement system for solving the above problems, a multi-channel detector (for example, a line sensor such as CCD) is arranged on a diffraction grating to simultaneously receive dispersed diffracted light in each wavelength band. There is something to do.

[0011]

In the above-mentioned conventional monochromator, it takes a long time to rotate the diffraction grating, so that there is a problem that it is difficult to examine the spectral characteristic of the incident light whose change with time is drastic. Further, in the case of using the specially shaped cam, there is a problem that the manufacturing becomes difficult because the cam needs to be processed with high precision.

In a spectroscopic measurement system using a multi-channel detector, there is a problem that adjustment and operation are troublesome because it is necessary to offset the light receiving element for each channel. Further, a multi-channel detector currently put into practical use generally has a low conversion efficiency, and thus is not suitable for measuring weak light. Further, since the degree of detector integration is related to the factor that determines the resolution, it cannot be used for measurements requiring high resolution.

Since the wavelength range in which the diffraction grating can diffract and the wavelength range in which the multi-channel detector can be detected are different depending on the element characteristics, for example, measurement is performed over a wide wavelength range from the visible range to the infrared range. In this case, it is necessary to replace each element, which is troublesome.

The present invention has been made in view of the above-mentioned problems of the prior art, and in measuring the spectral wavelength characteristics of incident light, it is possible to quickly perform measurement over a wide wavelength range. The purpose is to realize a measuring instrument.

[0015]

The spectroscopic measuring instrument of the present invention comprises:
Multiple diffraction gratings with different linear densities and detection sensitivity
Diffracted dispersed light by the diffraction grating with different center wavelengths
Spectrometer including a plurality of line sensors for receiving light
With multiple diffraction gratings and line sensors
A first and a second rotatable stage, and
And a control device for controlling the rotation state of the second stage.
The plurality of diffraction gratings and the line sensor are
On the second stage, the rotation axis and center of each stage are the same.
Place the circle so that the diffraction surface and the light-receiving surface are in contact with each other.
The control device is installed in the first step when performing the spectroscopic measurement.
The diffraction grating sequentially by rotating the laser
Detect the line sensor by rotating the second stage.
Grating whose center wavelength of degrees is currently used for diffraction dispersion
Switch to a wavelength close to the blaze wavelength of.

[0016]

[0017]

[0018]

[0019]

In the present invention constructed as described above,
Have different linear densities, and dispersion diffraction is performed efficiently.
Diffraction gratings with different wavelength ranges are switched sequentially
The center wavelength of the detection sensitivity is also used at the same time.
Since different line sensors can be switched, a wide wavelength range can be obtained.
Efficient dispersive diffraction over range and high
Sensitive detection is performed.

[0020]

[0021]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, FIG. 1 (a) is a top view schematically showing an optical arrangement, and FIG. 1 (b) is in FIG. 1 (a). 3 is a front view partially showing an installation state of the diffraction grating 103 of FIG.

The monochromator 10 shown in FIG.
0 indicates the incident light from the incident slit 101 to the diffraction grating 10
3, the light is split into light in a narrow specific wavelength band and is emitted from the emission slit 102. The diffraction grating 103 is shown in FIG.
As shown in the front view of (b), the rotary encoder 104 is connected to the rotary shaft of a motor 105, which is a DC motor, so that the rotation of the motor 105 is directly the rotation of the diffraction grating 103. There is. The rotating states of the diffraction grating 103 and the motor 105 are detected by a rotary encoder 104 provided between them.

A detection signal of the rotary encoder 104 is output to an output terminal 106 connected to the rotary encoder 104 via a cable 108. Further, the input terminal 107 is connected to the motor 105 via the cable 109, and the motor 105 performs a rotating operation according to the drive signal supplied to the input terminal 107.

As described above, the diffraction grating 103 is the motor 1
Since the same rotation as 05 is performed, the wavelength band of the dispersed diffracted light emitted from the emission slit 102 is determined according to the rotation angle. In the monochromator of the present embodiment, since the detection signal of the rotary encoder 104 indicating the rotation state of the diffraction grating 103 and the motor 105 is output from the output terminal 106, the detection signal is monitored to emit the current from the emission slit 102. It is possible to check the wavelength of the emitted light.

In this embodiment, as the rotary encoder 104, an absolute type encoder capable of detecting an absolute angle is used. The wavelength accuracy of the emitted light corresponding to the resolution of the rotary encoder 104 is
It depends on the number of pulses generated by 04 and the rotation angle of the diffraction grating. For example, rotary encoder 1
If 04 is used to generate 9 × 10 ⁵ pulses for one rotation, it is possible to configure the resolution of emitted light near the 0th-order diffracted dispersed light with a wavelength accuracy of 0.1 nm.

When wavelength sweeping is performed by continuously rotating the diffraction grating 103, the time required for this is dominant for the rotary encoder 104 to generate a pulse. The above-mentioned number of pulses can be generated in about 0.3 S, and extremely fast wavelength sweep can be performed.

FIG. 2 is a schematic diagram showing the structure of a measuring system using the monochromator shown in FIG. Figure 2 (a)
In the example shown in (1), the state in which the light generated by the light source 201 is dispersed by the monochromator 100 and the sample 202 is irradiated with this is examined for the reflection characteristic, absorption characteristic, or transmission characteristic of the sample 202. The light reflected or transmitted through the sample 202 is detected by the detector 203.

In the example shown in FIG. 2B, the sample 202 is irradiated with the light generated by the light source 201, and the light reflected or transmitted by the sample 202 is dispersed by the monochromator 100 and detected by the detector 203. There is.

The computer 205 stores the detection signal of the rotary encoder and the wavelength of the light emitted from the monochromator 100 in association with the detection signal. The computer 203 stores the detection signal via the input / output device 204. A signal S1 indicating the detected light intensity is input and connected to the monochromator 100. In addition, the display device 20
An image generation signal S5 is output to 6.

The computer 205, when an instruction input indicating that measurement is to be performed for a specific wavelength band is input to the input means (not shown), is output to the output terminal 106 (see FIG. 1) provided in the monochromator 100. The wavelength of the light currently emitted is confirmed from the detection signal S3 of the rotary encoder 104, and then the diffraction grating 103 (see FIG. 1)
The motor drive signal S4 for rotating the light in the direction in which the light in the specific wavelength band is emitted from the emission slit 102 (see FIG. 1) of the monochromator 100 is output to the input / output device 204. The input / output device 204 converts the digital motor drive signal S4 into an analog motor drive signal S2 by a built-in D / A converter and inputs it to the input terminal 107 (see FIG. 1).
Output to. Subsequently, when the computer 205 confirms that the wavelength of the light currently emitted from the detection signal S3 has become a light in a specific wavelength band, the computer 205 ends the rotation of the motor 105 and the diffraction grating 103.
4 is output. After this, the above-mentioned specific wavelength band and signal S
A signal S5 that causes the display device 206 to display an image with the light intensity indicated by 1 is generated and output. The person who inputs the instruction knows the spectral characteristics of the sample 202 by checking the displayed image.

The above-mentioned control operation by the computer 205 is also executed for a wavelength band having an arbitrary width.
By continuously rotating the diffraction grating 103, an arbitrary bandwidth is swept, and each wavelength at this time is obtained from the detection signal S3 of the rotary encoder 104, whereby the light intensity for each wavelength is displayed.

In this embodiment, since the diffraction grating is directly connected to the rotation shaft of the motor and the wavelength of the emitted light is confirmed by the output of the rotary encoder, the wavelength sweeping operation as described above can be performed at high speed. You can

Further, since the type of the detector for detecting the intensity of the incident light is not particularly limited, it is possible to use a highly sensitive element such as a photomultiplier, and the weak light can be measured with high accuracy and high speed. .

It has already been stated that the time required for the wavelength sweep to generate a pulse is dominated by the rotary encoder 104, but the detection output of the rotary encoder 104 and the light intensity detected by the detector 203 have been described. By providing a device for storing the signal S1 indicating the above, it is ensured that the above-mentioned time dominates, and such a configuration may be adopted.

Although the diffraction grating, the motor and the rotary encoder are directly connected to each other in this embodiment, in order to further increase the rotation speed of the diffraction grating, for example, a speed increasing mechanism as shown in FIG. May be attached. In the example shown in FIG. 3, the diffraction grating 103 and the motor 1
05 is directly connected to the pulleys 301 and 302 having different diameters (the diameter of the pulley 302 is small), and each pulley is connected to the belt 303.
The rotation of the motor 105 is accelerated and transmitted to the diffraction grating 103.
Even with such a configuration, since the rotation angle of the diffraction grating 103 is detected by the rotary encoder as in the case shown in FIG. 1B, an error due to speeding up does not occur in angle detection.

In this embodiment, it is important to detect the rotation angle of the diffraction grating with a rotary encoder,
The type of motor that rotates the diffraction grating is not particularly limited. Various types of motors such as a DC motor and an ultrasonic motor can be used, and the location where they are arranged is not particularly limited.

Further, there are rotary encoders that use optical detection and magnetic detection, but this type is not particularly limited, and various types can be used depending on the usage conditions and required detection accuracy. What is necessary is just to use.

FIG. 4 is a block diagram of the monochromator shown in FIG.
It is a figure which shows what provided 01. The other configuration is shown in FIG.
Since it is the same as the embodiment shown in FIG.

FIG. 4A shows the monochromator 4 of this embodiment.
01 is a top view showing the configuration of the control unit 401, and FIG. 4B is a block diagram showing the configuration of the control unit 401 in FIG. 4A.

The control unit 401 is a cable 1
It is connected to the rotary encoder 104 and the motor 105 via 08 and 109, and is composed of a control device 402, an input device 403, a memory 404 and a display device 405 as shown in FIG. 4B.

The controller 402 is the rotary encoder 1
The detection signal S42 of 04 and the signal S43 indicating the input information supplied from the input device 403 are input, and the drive signal S41 thereof is output to the motor 105.
A signal S44 for generating an image is output to S5. The controller 402 is also interconnected with a memory 404. The memory 404 stores the detection signal S42 and the wavelength of the light emitted from the monochromator 400 in association with the detection signal S42 in association with each other.

Next, the operation of this embodiment will be described.

The controller 402 is the rotary encoder 1
The signal S44 for displaying the wavelength stored in the memory 404 on the display device 405 is output corresponding to the detection signal S42 of 04.
The wavelength of the light emitted from 00 is displayed.

When the input device 403 receives an instruction input indicating that the measurement is performed for a specific wavelength band, the control device 4
02 confirms the wavelength of the light currently emitted from the monochromator 400 from the detection signal S42 of the rotary encoder 104, and then the diffraction grating 103 emits light in a specific wavelength band from the emission slit 102 of the monochromator 400. The motor drive signal S41 for rotating the motor 105 in the rotating direction is output to the motor 105. Subsequently, when the control device 402 confirms that the wavelength of the light currently emitted from the detection signal S42 has become the light in the specific wavelength band, the motor 1
05 and the motor drive signal S41 for ending the rotation of the diffraction grating 103 are output. The person who inputs the instruction is the display device 405
It is confirmed from the displayed image that the wavelength of the light currently emitted from the monochromator 400 has become the desired wavelength.

The above control operation by the controller 402 is
It is also carried out for a wavelength band having an arbitrary width. By rotating the diffraction grating 103 continuously, an arbitrary bandwidth is swept, and each wavelength at this time is swept by the rotary encoder 10.
The light intensity for each wavelength is displayed by obtaining from the detection signal S42 of No. 4 and the stored contents of the memory 404.

In each of the embodiments described above, the rotary encoder 104 is described as an absolute type that detects an absolute angle.
An incremental type that outputs a pulse together with a signal indicating the rotation direction at every predetermined angle may be used. In this case, the initialization is performed by the index output of the rotary encoder, and thereafter, the current rotation angle of the diffraction grating may be confirmed by the history of the pulse output.

Although the wavelength of the emitted light is stored in correspondence with the detection signal of the rotary encoder 104 and the current wavelength of the emitted light is confirmed from the stored contents, the current detection signal of the rotary encoder 104 is used. It is also possible to provide an arithmetic unit for calculating the wavelength of the emitted light of and to perform the confirmation. With this configuration,
Permanently requires less memory space.

FIG. 5 is a diagram showing the structure of a spectroscopic measuring device for performing high-speed scanning over a wide wavelength band, and FIG.
Is a top view schematically showing the optical arrangement, and FIG. 5B is a block diagram showing the configuration of the control unit 506 in FIG. 5A.

The spectroscopic measurement device 500 of this embodiment receives dispersed diffracted light from the diffraction grating provided on the stage 504 by means of a multi-channel line sensor provided on the stage 505.

[0051] Stage 504 and 505 together are configured to be rotated by a motor (not shown) to be built, are different three diffraction grating 502 _{1-502 3} groove densities respectively mounted on the stage 504, the stage 505 spectral sensitivity respectively different three line sensors 503 ₁ -
503 ₃ is installed.

[0052] Three of the diffraction grating 502 _{1-502 3} on the stage 504, the diffraction surface to a circle to the same rotation shaft and the center of the stage 504 is arranged in contact with, the line sensor 503 _{1 to 503 3} Is disposed on the stage 505 such that the light receiving surface is in contact with a circle having the same center as the rotation axis of the stage 505.

[0053] monochromator of the present embodiment 500, the light incident from the entrance slit 501 is diffracted dispersed either by the diffraction grating 502 _{1-502 3} on the stage 504, further diffraction dispersed spectroscopy stage 505
Is intended to received by any one of the line sensors 503 _{1 to 503 3} above.

The diffraction grating 502 _{1-502 3} and the line sensor 503 _{1 to 503 3} as the stage 504,
Since it is mounted on 505, the diffraction grating 50 is shown in the figure.
2 _1, the dispersion diffraction position and light receiving position the line sensor 503 ₁ is placed can put any diffraction grating and a line sensor of by rotating the stage 504 and 505.

[0055] groove density of grating 502 ₁ 1200 /
mm, a groove density of grating 502 ₂ 600 / mm, the groove density of the grating 502 ₃ is the 300 lines / mm, by using these sequential, light in the infrared region is efficiently dispersed from the ultraviolet region . Each of the line sensors 503 _{1 to 503 3} provided in combination with each diffraction grating 502 _{1-502 3} above, those central wavelength of detection sensitivity of the blaze wavelength near the corresponding diffraction grating is used, respectively There is.

The control unit 506 is shown in FIG.
As shown in FIG. 5, it comprises a control device, an input device 510 and a display device 511.
Is connected to each stage 504, 505 via the controls the rotation operation and the read operation of the line sensors 503 _{1 to 503 3} each motor built in each stage.

When the measurer inputs to the input device 510 that the incident light is to be spectroscopically measured, the control device 509 outputs a signal S51 for driving a motor incorporated in the stage 504 to disperse the diffraction dispersion of the incident light. each diffraction grating 502 for ₁ to
502 ₃ is sequentially switched. At the same time as switching the diffraction grating, a signal S52 for driving the motor built in the stage 505 is output to switch the line sensor that receives the diffracted dispersed light.

The controller 509 controls each line sensor 503.
From _{1 to 503 3} of the detection signal S53, and generates and outputs an image signal S54 to the image display light intensity for each wavelength of the incident light. The measurer confirms the spectral characteristic of the incident light on the display image of the display device 511. Each stage 5 in this embodiment
The motor used to rotate 04 and 505 is not particularly required to have high-speed rotatability, and therefore the type thereof is not limited. For example, when a DC motor is used, position detection may be performed in combination with a rotary encoder as in the embodiment shown in FIG. 1, and a limit for position detection may be provided around the stage instead of the rotary encoder. A switch or a proximity sensor may be provided. When a stepping motor is used, this type of position detection mechanism is unnecessary and the device configuration can be simplified.

Further, in this embodiment, three diffraction gratings and line sensors are used, but the number of them is not limited, and the number may be arbitrarily increased or decreased according to the measurement wavelength range. Good.

In the present embodiment, the light receiving elements are integrated, the wavelength is detected by a multi-channel line sensor capable of specifying the wavelength by each element, and the diffraction grating and the line sensor treated as a set are sequentially switched. By performing the measurement, spectroscopic measurement in a wide wavelength range could be performed at high speed and with high accuracy.

In each of the embodiments described above, the optical arrangement having no mirror is described for the sake of simplicity. However, the configuration of the present invention does not relate to the optical arrangement. For example, Czerny -Turner type, Littrow type, Eber
Of course, it can also be applied to a monochromator having an optical arrangement in which incident light is folded back by a t-type mirror and the path is long.

[0062]

Since the present invention is constructed as described above, it has the following effects.

[0063]

[0064]

[0065]

High diffraction efficiency over a wide wavelength band,
There is an effect that high-sensitivity spectroscopic measurement can be performed at high speed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.
FIG. 1A is a top view schematically showing an optical arrangement.
FIG. 1B is a front view partially showing an installation state of the diffraction grating 103 in FIG.

2 (a) and 2 (b) are each a schematic diagram showing a configuration of a measurement system using the monochromator shown in FIG.

FIG. 3 is a diagram showing an example of a rotation speed increasing mechanism for a diffraction grating.

FIG. 4 is a diagram showing the monochromator shown in FIG. 1 provided with a control unit 401 for making emitted light an arbitrary wavelength. FIG. 4A shows the configuration of the monochromator 401 of the present embodiment. The top view shown is (b), which is a block diagram showing the configuration of the control unit 401 in (a).

FIG. 5 is a diagram showing a configuration of a spectroscopic measurement device of the present invention,
7A is a top view schematically showing an optical arrangement, and FIG. 8B is a block diagram showing a configuration of a control unit 506 in FIG.

[Explanation of symbols]

100,400 monochromator 101 and 501 entrance slit 102 exit slit 103,502 _{1-502 3} diffraction grating 104 rotary encoder 105 motor 106 output terminal 107 input terminals 108,109,507,508 cable 201 light source 202 sample 203 Detector 204 output Device 205 Computer 206,405,511 Display device 301,302 Pulley 303 Belt 401,506 Control unit 402,509 Control device 403,510 Input device 404 Memory 500 Spectrometer 503 _{1 to} 503 ₃ Line sensor 504, 505 Stage S1 S5, S41 to S44, S51 to S54 signals

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Chitomi Tomita 5-4-1 Dobashi, Misaki-ku, Kawasaki City, Kanagawa Prefecture Photo Device Co., Ltd. (56) Reference JP-A-63-206624 (JP, A) JP 63-167226 (JP, A) JP-A-59-3329 (JP, A)

Claims (1)

[Claims] 1. A plurality of diffraction gratings having different linear densities.
, And the center wavelength of the detection sensitivity is different,
Equipped with multiple line sensors that receive diffracted dispersed light
A spectroscopic measuring device, wherein a plurality of diffraction gratings and a line sensor are mounted.
First and second rotatable stages, and a control for controlling the rotating states of the first and second stages.
And a plurality of diffraction gratings and line sensors,
On the second stage, the rotation axis and center of each stage are the same.
Place the circle so that the diffraction surface and the light-receiving surface are in contact with each other.
The control device rotates the first stage when performing the spectroscopic measurement.
Rotate the grating to switch the diffraction grating one by one, and receive the light.
Center of the detection sensitivity by rotating the second stage of the sensor
Brackets of the grating whose wavelength is currently used for diffractive dispersion
Spectral measurement characterized by switching to a wavelength close to
vessel.