JPH06100500B2 - Spectrometer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a spectroscopic measurement device applied to a measurement device that performs spectroscopic measurement over a wide wavelength range.

(B) Conventional technology and its problems In recent years, along with the development of optical communication technology, there is an increasing demand for spectroscopic measurement over a wide wavelength region for the characteristic test of various optical elements.

By the way, in the spectroscopic measurement over a wide wavelength range, it is necessary to use a plurality of diffraction gratings and a plurality of detectors due to the limitation due to the diffraction efficiency characteristic of the diffraction grating which is a dispersive element and the wavelength sensitivity characteristic of the detector. it is conceivable that.

Generally, as shown in FIG. 4, the diffraction grating does not show uniform and good diffraction efficiency characteristics over the entire wide wavelength region, but shows a decrease in efficiency on both sides of the blaze wavelength. Therefore, the wavelength range that can be measured by one diffraction grating is limited by the efficiency characteristics of the diffraction grating, and if a wide wavelength range (λ _{1 to} λ ₃ ) is to be measured, the short wavelength range ( A total of two diffraction gratings are required, a diffraction grating having high efficiency in λ _{1 to} λ ₂ ) and a diffraction grating having high efficiency in adjacent long wavelength regions (λ _{2 to} λ ₃ ).

The same applies to the detector, and it is necessary to use a detector having good wavelength sensitivity in each wavelength region of the wavelength range to be measured. That is, in the short wavelength region (λ ₁
The to [lambda] ₂₎ The detector has good wavelength sensitivity region, the detector having good wavelength sensitivity in the adjacent region in the long wavelength region (λ _{2 ~λ 3),} it is necessary to use each .

By the way, the conventional spectroscopic measurement device applied to various spectroscopic analyzers is based on the premise of spectroscopic measurement in a relatively narrow wavelength range. (A) Single diffraction grating and single detector (B) two diffraction gratings are switched and used, but a single detector is used, and (C) one diffraction grating and two detectors are used. There is one in which two detectors are used and both detectors are manually switched.
All of these devices are limited by the characteristics of a single diffraction grating or a single detector and cannot cover a sufficiently wide wavelength range. I couldn't meet my request.

For this, of course, an apparatus provided with a plurality of diffraction gratings and a plurality of detectors is conceivable, but a spectroscopic measurement apparatus over a wide wavelength region can be provided by simply providing a plurality of diffraction gratings and detectors. This is not possible, and it is necessary to provide various mechanisms such as a mechanism for switching the diffraction grating and the detector for each region of the measurement wavelength, and if these mechanisms do not operate smoothly, measure it. There are problems that continuous measurement cannot be performed in the entire wavelength range, and that the diffraction grating and the detector are relatively displaced with respect to the incident measurement light and the measurement accuracy is degraded.

The present invention has been made in view of the above problems, and an object of the present invention is to enable accurate and continuous spectroscopic measurement over a wide wavelength range.

(C) Means for Solving the Problems In order to achieve the above-mentioned object, the present invention has grating planes continuous in a state of being flush with each other and having good diffraction efficiency in wavelength regions different from each other Are two diffraction gratings having the same grating constant, and when these diffraction gratings are at a predetermined rotation angle, the diffraction gratings are slid and displaced along the spread direction of the grating surface and positioned with respect to the incident measurement light. Switching drive mechanism for switching the two, the two detectors having good wavelength sensitivity in the wavelength region corresponding to the diffraction efficiency of each diffraction grating, and the optical path of the diffraction light of the diffraction grating is switched at high speed. And a switch means for switching the detection output of the detector in synchronism with the switching operation of the diffraction grating. Is configured.

(D) Action According to the above configuration, in the short wavelength region, one diffraction grating and one detector having good characteristics in the region are involved in the spectroscopic measurement, and the rotation angle of the diffraction grating exceeds the predetermined angle. When the switching drive mechanism is driven, the diffraction grating is switched with respect to the measurement light, and the switch means is switched. In the long wavelength region, the other diffraction grating and the other detector having good characteristics in the region are used for spectroscopic measurement. Will be involved in.

In addition, each diffraction grating can be continuously spectroscopically measured over the entire range from the short wavelength to the long wavelength by the structure in which the grating surfaces are continuous with each other in the same plane, and the diffraction gratings have the same grating constant. The rotation speed of the diffraction grating can be the same.

(E) Example Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a configuration diagram of a spectroscopic measurement device according to an embodiment of the present invention. The spectroscopic measurement device includes two diffraction gratings 1 and 2 of a first type and a second type, and these diffraction gratings 1 and 2. A rotation driving mechanism 3 for rotating 2 at a predetermined position, a switching driving mechanism 4 for switching the positions of both diffraction gratings 1 and 2 with each other, first and second two detectors 5 and 6, and these detectors. An optical path switching means 7 for switching the optical paths to 5 and 6 and a main body circuit 8 for selectively sending the detection outputs of both detectors 5 and 6 are provided, and the main body circuit 8 includes both detectors 5 and 6. Switch means 9 for switching the detection output is provided.

In front of the optical path to both diffraction gratings 1 and 2, the entrance slit 10
And a spherical or parabolic reflecting mirror 11 are provided, and the measurement light is incident on either of the diffraction gratings 1 and 2 as parallel light via the entrance slit 10 and the reflecting mirror 11.
The diffraction gratings 1 and 2 have good efficiency characteristics in the wavelength regions adjacent to each other. That is, the first diffraction grating 1 has good efficiency characteristics in the short wavelength region (λ _{1 to} λ ₂ + Δλ ₃ ), and the second diffraction grating 2 has the long wavelength region partially overlapping the short wavelength region. (Λ ₂ −Δλ _{2 to} λ ₃ ) has good efficiency characteristics. Both diffraction gratings 1 and 2 are connected in a state where the grating surfaces are flush with each other. Also, both diffraction gratings
1 and 2 have the same lattice constant, but differ only in the blaze wavelength. Both diffraction gratings 1 and 2 are separately manufactured 2
It may be one obtained by butting and joining together a plurality of diffraction gratings, or may be one in which two types of grating surfaces are formed on a single substrate.

Both of the diffraction gratings 1 and 2 are rotated at a predetermined position where the measurement light is incident by the rotation driving mechanism 3 such as a sine bar mechanism, and when the rotation angle position reaches a predetermined rotation angle position, the replacement driving mechanism 4 is driven. The positions are switched with respect to the incident measurement light by sliding displacement in the direction in which the grating surface spreads and in the direction orthogonal to the grating grooves. In addition,
The specific structure of the support portion that supports both the diffraction gratings 1 and 2 in a rotatable and slidable manner will be described later.

A reflection oblique mirror 12 and an exit slit 13 are provided at the latter stage of the optical paths of the diffraction gratings 1 and 2, and the diffracted light by the diffraction gratings 1 and 2 is reflected again by the reflection mirror 11 and then the reflection oblique mirror 12 The light is incident on the detectors 5 and 6 through the exit slit 13.

The first and second detectors 5 and 6 have wavelength sensitivities corresponding to the efficiency characteristics of the diffraction gratings 1 and 2, respectively, and the first detector 5 has a short wavelength region (λ ₁ ~ Λ ₂ + Δ
λ ₃ ) has good wavelength sensitivity, and the second detector 6 has a long wavelength region (λ ₂ −Δλ ₂₎ that partially overlaps the short wavelength region.
˜λ ₃ ) with good wavelength sensitivity. Both detectors 5,6
A lens 14 and the optical path switching means 7 are provided in the preceding stage of the optical path of, and the diffracted light that has passed through the exit slit 13 is condensed on the detectors 5 and 6 via the lens 14 and the optical path switching means 7. It is supposed to be incident. The optical path switching means 7 is a rotary chopper whose surface is a mirror surface, and rotates at a high speed in a posture of obliquely traversing the optical path of the diffracted light. The diffracted light that has passed through the optical path switching means 7 is condensed on the first detector 5, and the diffracted light whose optical path has been switched by the optical path switching means 7 is second detector 6
Focus on.

The main body circuit 8 to which the detection outputs of both detectors 5 and 6 are input is the second
As shown in the block diagram of the figure, first and second amplifiers 15 and 16 for amplifying the detection outputs of the detectors 5 and 6, respectively,
A phase shifter 17 that shifts the phase of one of the amplified outputs of the amplifiers 15 and 16 (the output of the second amplifier 16 in this embodiment), the output of this phase shifter 17 and the output of the other first amplifier 15 And a post-stage amplifier 18 for amplifying the output of the switch means 9.
The output of the post-stage amplifier 18 is synchronously rectified and then sent to a display device or a recording device (neither is shown) for performing spectrum display. By the operation of the phase shifter 17, the phases of the outputs of the first and second amplifiers 15 and 16 are aligned. The switch means 9 is adapted to switch in synchronism with the switching operation of both diffraction gratings 1 and 2.
When the first diffraction grating 1 is at the measurement light incident position, the detection output of the first detector 5 is sent out, and when the second diffraction grating 2 is at the measurement light incident position, the detection output of the second detector 6 Is sent. Specifically, the switching operation of the switch means 9 is performed by a signal from a signal generator 3a attached to the rotary drive mechanism 3 for the diffraction gratings 1 and 2.

FIG. 3 is a perspective view showing the structure of the support portion of the diffraction gratings 1 and 2, and as shown in the figure, the support portion is a frame that rotates integrally with the sine bar 19 around a predetermined rotation axis P. 20, a slide base 22 slidably supported on the front surface of the frame 20 by guides 21, 21 in a direction orthogonal to the rotation axis P, and a rack 24 attached to the slide base 22 and in which a pinion 23 meshes. Therefore, two diffraction gratings 1 and 2 are attached to the front surface of the slide base 22. The pinion 23 is located on the rotation axis P and is rotated by the driving of the replacement drive mechanism 4, and the slide base 22 is slid and displaced to bring the positions of the diffraction gratings 1 and 2 to each other without affecting the rotation of the frame 20. It is supposed to be replaced. Since both diffraction gratings 1 and 2 are supported by such a supporting portion, rotation at the measurement light incident position and slide displacement along the spreading direction of the grating surface can be performed separately.

In the above configuration, the short wavelength side (λ ₁ ~
If spectroscopic measurement is performed from λ ₂ ), in that case, the first diffraction grating 1 is at the measurement light incident position, and the switch means 9 is connected to the first detector 5 side in the main body circuit 8. is doing. Therefore, the measurement light is dispersed and diffracted by the first diffraction grating 1, and the diffracted light is transmitted through the optical path switching means 7 to both detectors 5,
Incident on 6. Although photoelectric outputs are output from the detectors 5 and 6, respectively, since the switch means 9 in the subsequent stage is switched to the first detector 5 side, only the detection output of the first detector 5 is the main circuit 8 Sent from. Therefore, in the short wavelength region, the measurement light is diffracted by the first diffraction grating 1 and the diffracted light is detected by the first detector 5.

In this state, both the diffraction gratings 1 and 2 are rotated by the drive of the rotation drive mechanism 3 to the angular position for sending out the diffracted light of long wavelength, and when the rotation angle reaches a predetermined value (λ ₂ −Δλ ₂ ), the replacement drive When the mechanism 4 is activated, the diffraction gratings 1 and 2 start to slide, and when the rotation angle reaches the next predetermined value (λ ₂ + Δλ ₃ ), the positions of the diffraction gratings 1 and 2 are completely exchanged, The second diffraction grating 2 is located at the measurement light incident position. Therefore, in the long wavelength region, the second diffraction grating 2 disperses and diffracts the measurement light, and the diffracted light enters the detectors 5, 6 side.

On the other hand, when the rotation angle of both diffraction gratings 1 and 2 reaches the angular position corresponding to the boundary (λ ₂ ) in both the long and short wavelength regions, the switch means 9 is supplied with the signal from the signal generation unit 3a of the rotation drive mechanism 3.
Switches to the second detector 6 side. As a result, the detection output of the second detector 6 is transmitted from the main body circuit 8 in the long wavelength region. Therefore, in the long wavelength region, the measurement light is diffracted by the second diffraction grating 2 and the diffracted light is detected by the second detector 6.

(F) Effect As described above, according to the present invention, one diffraction grating and one detector having good characteristics in the short wavelength region are involved in the spectroscopic measurement, and Since the other grating and the other detector, which have good characteristics in the region, are involved in the spectroscopic measurement, the spectroscopic measurement over the entire wavelength range to be measured can be covered by the well-characterized grating and the detector. This enables accurate spectroscopic measurement in a wide wavelength range.

Moreover, since the grating surfaces of both diffraction gratings are continuous with each other and the positions are switched by sliding in the spreading direction of the grating surface, one diffraction grating diffracts the measurement light and the other diffraction light shifts to diffraction. Therefore, it is possible to continuously perform spectroscopic measurement over the entire wavelength range without interrupting the measurement in the middle of the wavelength range, and the positional displacement due to the replacement of the diffraction grating hardly occurs. Therefore, accurate measurement can be performed. Can be done.

Further, since the diffraction gratings have the same grating constant, the rotational speeds of the respective diffraction gratings can be the same, which allows the same rotary driving mechanism for the diffraction gratings to be used as a result. Can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a main circuit portion thereof, FIG. 3 is a perspective view of a support portion of a diffraction grating, and FIG. 4 is a diagram for explaining the operation. It is a characteristic diagram. 1, 2 ... Diffraction grating, 3 ... Rotation drive mechanism, 4 ... Replacement drive mechanism, 5, 6 ... Detector, 7 ... Optical path switching means, 9
...... Switch means.

Claims (1)

[Claims] 1. Diffraction gratings of two types in which grating planes are continuous with each other and have good diffraction efficiency in wavelength regions different from each other in length and length, and further, each has the same grating constant, and these diffraction gratings are provided. A switching drive mechanism that slides and displaces the diffraction grating along the spread direction of the grating surface at a predetermined rotation angle to switch the position with respect to the incident measurement light, and a wavelength corresponding to the diffraction efficiency of each diffraction grating. Two detectors having a good wavelength sensitivity in the area, an optical path switching means for switching the optical paths of the diffracted light of the diffraction grating at high speed and alternately guiding the diffracted light to both detectors, and a switching operation of the diffraction grating. A spectroscopic measurement apparatus comprising: a switch unit that switches the detection output of the detector in synchronization.