JPH11142240A - Spectroscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spectroscope by which beams of measuring light from a sample can be measured simultaneously in a wide measuring wavelength range and by which arbitrary different wavelength regions can be measured simultaneously. SOLUTION: A spectroscope is provided with a plurality of slits 10a, 10b which are arranged in different positions in the X-direction and the Y-direction, with an optical system containing diffraction grating 13 by which beams of light incident from the plurality of slits 10a, 10b are wavelength-dispersed and with a CCD detector 17 which receives light radiated from the optical system. The CCD detector 17 whose light receiving face is a two-dimensional plane is used as a photodetector. The optical system is constituted in such a way that the respective beams of light from the plurality of slits 10a, 10b are received in different positions on the light receiving face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectroscopic device, and more specifically, to a spectroscopic device as a light detecting means.
The present invention relates to a spectroscopic device using a two-dimensional multi-channel photodetector such as D (referred to as an array element).

[0002]

2. Description of the Related Art As is well known, a so-called polychromator using an array element is a spectroscope that detects light diffracted in accordance with a wavelength by an array element spatially arranged instead of rotating a diffraction grating. It is.

FIG. 1 is a main part configuration diagram showing an example of a conventionally used polychromator. In the figure, light emitted from a fiber 1 is converted into a parallel light beam by a collimating mirror 2 and enters a dispersion element (here, a diffraction grating) 3. The light that has exited the diffraction grating 3 is focused by a focusing mirror 4 and irradiated onto an array element 5. In this case, if the diffraction grating 3 is fixed without being rotated, the diffraction angle changes according to the wavelength of the incident light, and the position of the light spot hitting the array element 5 changes (moves). Therefore, the wavelength of the incident light can be known from the position of the light spot.

As a spectroscope capable of expanding a measurement wavelength range while ensuring a desired wavelength resolution, a conventional spectroscopic apparatus disclosed in Japanese Patent Laid-Open No.
There is an apparatus disclosed in Japanese Patent No. 4464. The invention disclosed in this publication cannot be the basis of the present invention, but is common in having a plurality of entrances (slits).

That is, as shown in FIG. 2, a plurality of slits 6 and 7 are provided.
And the light in the wavelength range λ20 ± Δλ enters from the slit 7. Then, the relative positions are adjusted so that the light from each of the slits 6 and 7 is emitted from the dispersion element 3 at the same diffraction angle. Thereby, the light from each of the slits 6 and 7 can be received by the same array element 5, and the measurement wavelength range can be expanded while securing a desired wavelength resolution.

[0006]

However, in the device disclosed in the above-mentioned publication, light is received at the same position on the array element 5, so that the measurement wavelength range is enlarged, The range cannot be measured simultaneously. Accordingly, the same problem as the conventional apparatus shown in FIG. 1 is pointed out in that the light emitted simultaneously from the same sample cannot be measured strictly even if the measurement wavelength range is expanded. Have.

When measuring spectra in different wavelength ranges, the spectral intensities often differ. In such a case, in the conventional apparatus, it is necessary to adjust the exposure time according to the spectrum, and it is difficult to measure a wide measurement wavelength range at the same time.

[0008] The present invention has been made in view of the above background, and an object of the present invention is to solve the above-mentioned problems and to simultaneously measure measurement light from a sample in a wide measurement wavelength range. Another object of the present invention is to provide a spectroscopic device capable of simultaneously measuring arbitrary different wavelength ranges and making the exposure time the same even when the spectral intensities are different.

[0009]

In order to achieve the above-mentioned object, in the spectroscopic device according to the present invention, a plurality of incident light sources arranged at different positions in both the X direction and the Y direction crossing the X direction are provided. The optical system includes an aperture, an optical system including a dispersive element that wavelength-disperses the light incident from the plurality of entrances, and a light detection unit that receives light emitted from the optical system. The light detecting means is configured such that a light receiving surface is a secondary plane, and the optical system receives light from the plurality of entrances at different positions on the light receiving surface. ). The entrance may be a slit or an output end of an optical fiber (claim 2). Further, the formation position of the entrance may be changeable.

In the present invention, "X direction and Y direction" mean axes of a virtual coordinate system defined for convenience. In short, if an entrance is provided at a different position not only in one-dimensional direction but also in two-dimensional direction. Good.

[0011]

FIG. 3 shows a preferred embodiment of the spectrometer according to the present invention. As shown in the figure,
The light incident from the slit serving as the entrance formed in the slit plate 10 is reflected by the first spherical mirror 11 and converted into a parallel light beam, and the parallel light beam is applied to the diffraction grating 13 as a dispersion element to disperse the wavelength. The wavelength-dispersed light is emitted to the second spherical mirror 15 to be reflected and condensed, and is focused on a predetermined position on the light receiving surface of the CCD detector 17 which is a two-dimensional photodetector. Such a basic optical system is the same as that generally used conventionally.

The first feature of the present invention is that a two-dimensional detector is used as the detector. Furthermore, a plurality of slits (two in this embodiment)
) Are provided. Further, as shown in FIG. 4, the two slits 10a and 10b are formed at positions shifted from both the slit width (X direction) and the direction orthogonal to the slit width (the direction in which the slit extends: the Y direction). Is formed.

Each light emitted from each of the slits 10a and 10b is converted into a first spherical mirror 11 and a diffraction grating 13 respectively.
In addition, the direction of each optical component is adjusted so that the wavelength is dispersed through the second spherical mirror 15 and the dispersed wavelength region is imaged at different positions of the CCD detector 17 in parallel with the main cross section. The different position is defined as Y, which is orthogonal to the X direction when the direction in which the wavelength is dispersed is the X direction as shown in the figure.
The position (row) is shifted by a predetermined distance in the direction. That is,
In the illustrated example, an image is formed shifted vertically.

With this configuration, the CCD detector 17 can separate the signals received in each row and take out the signals. As shown in the figure, the spectrum of the light incident from each of the slits 10a and 10b can be calculated from the split signals as shown in the figure. Can be obtained. That is, the light simultaneously incident from the slits 10a and 10b is simultaneously received by the CCD detector 17 and can be detected.

Therefore, in this embodiment, the measuring light from the sample is
In the middle, it is divided into two, and each is divided into two slits 1
By introducing the light into the light detectors 0a and 10b, the light incident simultaneously can be simultaneously detected by the CCD detector 17, respectively. Therefore, it is excellent in quantitative analysis.

If the wavelength ranges obtained by wavelength-dispersing the light from the slits are arranged so as to be continuous, the detection signals are connected to form a wide wavelength range with the same resolution in one measurement. Can be measured. If the wavelength range to be measured is far away and a wavelength range in the middle is unnecessary, the position of the entrance slit is set to a position corresponding to the required wavelength range, so that only the necessary wavelength range is selected. Can be detected. What is remarkable is that a plurality of continuous or discontinuous wavelength ranges can be measured simultaneously. That is, since the measurement can be performed based on the measurement light emitted from the sample at the same time, a true value with high accuracy can be measured.

As an example, a case where the hydrogen concentration in silica glass is determined will be described. The silica glass used for optical fibers and optical elements such as, H ₂ and as impurities Si-
Hydrogen exists in the form of OH, and the viscosity and transmittance in the near-infrared region decrease due to such impurities. Therefore, it is necessary to measure the hydrogen concentration nondestructively and in a relatively short time,
Such measurements are currently performed solely by Raman spectroscopy. Then, the measurement is performed as shown in FIG.
H ₂ peak appearing around 130 cm ^-1 (indicated by an arrow)
And 80 of SiO ₂ as an internal standard shown in FIG.
This is performed by calculating an intensity ratio (or area ratio) with a peak (indicated by an arrow) appearing near 0 cm ^-1 .

Therefore, conventionally, since the wavelength ranges are different, each of them has been measured separately. So, strictly speaking,
Since the measurement light is not emitted from the same sample, the light emitted each time may be different due to the state of the sample or other factors. In this embodiment, the slits 10a, 1
By setting the position of Ob appropriately, the above-mentioned H ₂
And a wavelength spectrum including two peaks of SiO ₂ can be simultaneously detected, and correct quantification can be performed.

Further, as apparent from FIG. 5, the intensities of the two peaks are different. In such a case, if both are measured in the same range, one peak may not be accurately extracted. In that case, by making the light intensity incident on each slit different according to the spectrum intensity, the intensity of the received signal obtained based on both wavelengths can be made substantially equal while the exposure time of the CCD is the same. Then, even when the received signal intensities are substantially equal, the actual spectrum intensity can be correctly calculated and obtained because the ratio of the light intensity of the incident light to the slits 10a and 10b is known.

An apparatus configuration for performing such processing can be, for example, as shown in FIG. In the figure, reference numeral 20 denotes a polychromator, which is configured by arranging slits 10a and 10b and two spherical mirrors and a concave mirror shown in FIG. Then, an image is formed on the CCD detector 17 at the final stage and received.

In such an apparatus, the measuring light emitted from the sample 22 is split into two lights by using a half mirror 23. At this time, the transmission / reflectance of the half mirror 23 is 1: 1.
Rather, by making them different, the amounts of transmitted light and reflected light can be made different. Then, the light distributed to the two is transmitted to a predetermined position by an optical fiber 25, and is condensed by a lens 26, so that the polychromator 2
The light is incident on the CCD detector 0, is wavelength-dispersed, and forms an image on the CCD detector 17.

Further, as shown in the figure, when an optical fiber is used, light emitted directly from the optical fiber without using a slit may be made to enter a polychromator without providing a slit. In such a case, the output end of the optical fiber becomes the entrance.

In the illustrated embodiment, the optical fiber 25
Is provided in the vicinity of the output end of the shutter. That is, in order for the CCD detector 17 to detect light, if light is received on the light receiving surface for a certain period of time, then the light receiving surface is shielded from light so that the light is not irradiated, and the light signal received during the light shielding Is converted to an electric signal and output.
In order to perform such processing, usually, a shutter is attached to the CCD detector 17, and the above processing is performed by controlling the opening and closing of the shutter.

However, when the shutter is opened and closed, the entire light receiving surface does not open and close instantaneously, but a time lag occurs between a portion where the shutter starts to close first and a portion where all the shutters are finally closed. In particular, in the case of a two-dimensional photodetector having a large light receiving surface as in the present invention, the difference becomes large, which leads to a difference in exposure time and affects measurement accuracy. Further, when the light source is placed at a branched position, a difference in exposure time occurs depending on the wavelength. Therefore, as shown in the figure, a shutter 28 is provided at the output end of the optical fiber 25 whose light diameter is reduced by converging the light, so that the area to be opened and closed can be reduced, and the whole can be instantaneously shielded. Thus, the exposure time can be made substantially the same at any position on the light receiving surface of the CCD detector 17, and the difference in the exposure time due to the wavelength is eliminated, so that the accuracy is further improved.

In order to exhibit such a function, the slits may be located near the slits 10a and 10b, or as shown in FIG.
As shown in (2), a shutter 28a may be provided at a position where light converges between the lenses L1 and L2. Further, as shown in the figure, the same effect can be obtained even if the shutter 28b is provided at the pupil position. Of course, various structures and mechanisms of the shutter itself can be used. It is needless to say that providing a shutter at such a position in relation to the present invention is preferable in terms of accuracy, but a conventional method may be used. Conversely, this technique (providing a shutter) can of course be applied to a conventional spectroscope.

In the above-described embodiment, an example in which two entrances such as slits are provided is shown. However, the present invention is not limited to this, and three or more entrances may be used.

In the above-described example, the slit position is fixed. However, the present invention is not limited to this. Although not shown, a predetermined slit formation position is shifted, and the wavelength to be measured is adjusted. The region may be adjustable. To adjust the slit position, for example, a long hole is provided in the slit plate 10 in the X direction, a slide plate that covers a part of the long hole is provided, and a slit is formed in the slide plate. Then, the slit position can be shifted by shifting the slide plate in the X direction with the slit formed in the slide plate serving as an entrance. Further, when the output end of the optical fiber is the entrance, the position of the entrance can be easily changed and adjusted by moving the end of the optical fiber.

[0028]

As described above, in the spectroscopic device according to the present invention, by setting the position of the entrance such as the slit at an appropriate position, the measuring light from the sample can be simultaneously measured in a wide measuring wavelength range. In addition, arbitrary different wavelength ranges can be measured simultaneously, and the exposure time can be the same even if the spectral intensities are different.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a conventional technique.

FIG. 2 is a diagram illustrating a conventional technique.

FIG. 3 is a diagram showing one embodiment of a spectroscopic device according to the present invention.

FIG. 4 is a diagram illustrating an example of a slit.

FIG. 5 is a diagram illustrating an operation.

FIG. 6 is a diagram illustrating an example of an installation state of a spectroscopic device.

FIG. 7 is a diagram showing a main part of a modification of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Slit board 10a, 10b Slit (entrance) 11 1st spherical mirror 13 Diffraction grating (dispersion element) 15 2nd spherical mirror 17 CCD detector

Claims (3)

[Claims] 1. An image processing apparatus comprising: a plurality of entrances arranged at positions different from each other in an X direction and a Y direction crossing the X direction; and a dispersion element for wavelength-dispersing light incident from the plurality of entrances. An optical system, comprising: a light detection unit that receives light emitted from the optical system, wherein the light detection unit has a light receiving surface that is a secondary plane, and the optical system includes: A spectroscopic device, wherein light is received at different positions on the light receiving surface. 2. The spectroscope according to claim 1, wherein the entrance is a slit or an output end of an optical fiber. 3. The spectroscopic device according to claim 1, wherein a position at which the entrance is formed can be changed.