JPS63120230A - Spectrophotometer - Google Patents

Abstract

PURPOSE:To almost linearily form a dispersion image on a light receiver array with respect to all of wavelengths, by arranging the light receiver array at the predetermined optimum position inside the Rowland circle of a concave diffraction lattice. CONSTITUTION:A light receiver array 5 is arranged to the Rowland circle 2 of a concave diffraction lattice 1 at the optimum position 0.125-1.5% inside the diameter of said circle 2 and a dispersion image is almost linearily formed within a range of -1.8-+1.8 deg. to the normal line passing the center of the grating 1 with respect to all of wavelengths and the sensitivity wavelength band half value width errors of array elements coincide at the min. Therefore, when a sensitivity wavelength band half value width is allowed to coincide with the wavelength interval of the array elements through an incident slit 3, the integral of radiation energy and the multiple integral of a spectrum and tristimulus values for calculating a measured value can be accurately performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention makes it possible to accurately measure light source color and object color in a short time, and is useful for color monitors, light sources, and CRT displays in color matching and automatic coloring. This invention relates to a spectrophotometer that accurately evaluates the color of light.

2. Description of the Related Art Conventionally, there has been a spectrophotometer in which a linear image sensor is placed at the exit slit of a general diffraction grating monochromator and used as a multichannel photoelectric detector. (For example, Uchida et al., "Spectrophotometry System Using Linear Sensor J (1983) No. 73P, 198 Interface"), Kakui et al., "Photometric Characteristics of Solid-State Image Sensors and Application to Spectrometry," Journal of the Illumination Society of Japan V.

1.61 No. 7 PI3 (1972)) The primary purpose of all of these devices was to observe spectral profiles.

Problems to be Solved by the Invention In general, a diffraction grating monochromator has a structure in which light of a certain wavelength is imaged onto an exit slit. At this time, the imaging plane of the dispersed image formed near the exit slit is not a plane.

For example, in the case of a monochromator using a concave diffraction grating, a circle whose diameter is the radius of curvature R of the concave grating (Rowla
If we place an input slit on the nd circle), all the light will travel around the circumference of this Rowland circle in order of wavelength.
-Image formed. Therefore, when trying to detect this wavelength-resolved light with a linear (plane) receiver array,
A linear dispersion image with respect to wavelength is not formed on the light receiving surface,
For example, when the center of the light-receiving surface is placed on the Rowland circle, the wavelength of the dispersed light projected onto the light-receiving surface becomes wider as it approaches the edge of the light-receiving surface. In other words, the line dispersion changes significantly.

Since the shape of the effective sensitivity region of each element of the photoreceiver array is the same, the sensitivity wavelength band characteristics for each array also change.

Calculate the energy integral of radiation through spectrometry and the colorimetric value.
In order to accurately perform the weighted integration of the spectrum and the triad value, it is necessary to determine the wavelength interval at the center of the photoreceiver array (calculated from the line dispersion on the photoreceptor surface and the distance between the photoreceiver arrays). and the half-width of the sensitivity wavelength band of each photoreceiver array must match. (For a detailed explanation of this, see Watai: Application of Radiation, Illuminating Society of Japan, Kaiun Measurement Study Group Material AR-8.
1-20 (1981). ) Therefore for this,
The half-width of the sensitivity wavelength band of each array of photodetectors must be constant, and that value must match the wavelength spacing of the arrays.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides optical receivers such that the light-receiving surface at the center of the receiver array is located slightly inside the circumference of the Rowland circle of the concave diffraction grating. Place the array,
Dispersed light is projected onto a photoreceiver array linearly with respect to wavelength.

Effect: By projecting the dispersed light linearly with respect to wavelength onto the photoreceiver array by the above means, the half width of the sensitivity wavelength band of the photoreceiver array can be made the same for all arrays. By using the entrance slit width to match the half-width of the sensitivity wavelength band to the wavelength interval of the array (determined from the linear dispersion of the monochromator), the spectrum and tristimulus can be used to calculate the radiation energy integral and colorimetric value. It is possible to accurately perform weighted integration with values, and the colorimetric accuracy is improved.

Embodiment As an embodiment of the present invention, a spectrophotometer will be described in which a photodetector array is arranged 0.13% inside the Rowland circle of a concave diffraction grating. FIG. 1 shows the configuration of the spectrophotometer described above. In the figure, 1 is a concave diffraction grating, and 2 is a Rowland circle of the concave diffraction grating 1. When an entrance slit 3 is provided on the circumference of the Rowland circle 2 and light is guided from the outside to the concave diffraction grating 1 through the entrance slit 3, the resulting dispersed image 4 is formed along the Rowland circle 2. This dispersed image 4 is focused on a photoreceptor array 5 placed inside the Rowland circle by 0.13% of the diameter of the Rowland circle of the concave diffraction grating.

Let us consider the dispersion of the diffraction grating in an actual example.

The focal length R of the concave diffraction grating 1 is 200 mm, and the groove interval d
: 1/150 m111, and the entrance slits are arranged at positions that are 5" from the center normal of the diffraction grating. If the angle between the center normal of the diffraction grating and the diffracted light is β, the linear dispersion is is given by the following formula, where m is an integer.

In order to detect the diffracted light in the normal dispersion region of the concave diffraction grating,
If β is set with no detection area between -1.8° and +1.8°, then the dispersion image will be on the Rowland circle 2 with a wavelength of 37
The wavelength range is from 0 nm to 790 nm. Roughly β = +
1. The line dispersion at 86 knots is 0.04O40 from equation (1).
07 (/nm), therefore the change in linear dispersion within the detection region is 0.
．． From 04000 to 0.04007 and wavelength 370nm
In the darkness of 790 nm from 0.02 on Rowland circle 2
Within %, there is almost no change.

In addition, since the mechanical width of the dispersion image 4 on the Rowland circle 2 between wavelengths 370 nm and 790 nm is approximately 16 mm, the curvature of the dispersion image 4 on the Rowland circle during this period is 0.13% inside the Rowland circle of the concave diffraction grating. , that is, an image is formed on the photoreceiver array 5 arranged 0.26n+lT+ along the center normal of the concave diffraction grating and inside the Rowland circle.

At this time, if a photoreceiver array 5 with an array spacing of 50 microns is used, it is possible to capture a spectrum between wavelengths 370 nm and 790 nm with a resolution divided into 320. At this time, the wavelength spacing and sensitivity wavelength band characteristics of each array of the photoreceiver array 5 hardly change, and highly accurate photometric color can be realized. Figure 2 shows the actual wavelength position of each element.
The wavelength shift is shown when the wavelength interval of each element is constant (0,9 nn).

Furthermore, using the input slit width, the half-width of the sensitivity wavelength band is
By matching the wavelength interval of the array (determined from the linear dispersion of the monochromator), it is possible to accurately integrate the energy of radiation and the unit value integration of the spectrum and tristimulus values to obtain the colorimetric value. The coloring accuracy is improved.

Effects of the Invention As described above, with the configuration of the present invention, by bringing the photoreceiver array to the optimal position, the dispersed light is projected onto the photoreceiver array most linearly with respect to the wavelength. The half-width of the sensitivity wavelength band of the receiver array can be matched with minimal error for all arrays, and the input slit width can be used to match the half-width of the sensitivity wavelength band with the wavelength spacing of the array (monochromator). (determined from line dispersion), it is possible to accurately integrate the energy of radiation and the unit price integration between the spectrum and the three-striped value in order to obtain the embellishment value, and the embellishment accuracy improves.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a spectrophotometer according to an embodiment of the present invention, and Fig. 2 is a characteristic diagram showing the deviation of the wavelength position of each element of the photoreceiver array in the spectrophotometer from a uniformly spaced wavelength scale. be. 1. 6 concave diffraction grating 202. Rowland yen 32
．． . Incidence slit 4°. 7 dispersion image 518. receiver array

Claims (1)

[Claims] In a spectrophotometer that combines a concave diffraction grating, an incident slit, and a photoreceiver array having the function of simultaneously receiving and measuring the light spectrum from the concave diffraction grating, the diameter of the Rowland circle of the concave diffraction grating is 0.125 to 0.125. 0.15%
, the photoreceiver array is arranged inside the Rowland circle, and the angle is from −1.8° to +1.8° with respect to the center normal of the concave diffraction grating.
A spectrophotometer, characterized in that a dispersion image between .degree. and .degree.