JPS6344188B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a densitometer using a so-called solid-state image sensor as a detector.

A solid-state image sensor is composed of, for example, a photodiode array, but the light-receiving elements are minute, and the light-receiving elements are arranged in a straight line or (and)
It has characteristics such as being able to be arranged in a planar shape and having a fast response, and can be suitably used as a detector for a densitometer equipped with a spectroscopic mechanism.

Figure 1 shows the schematic configuration of a densitometer that uses a solid-state image sensor as a detector to perform dual-wavelength measurements. 1 is a white light source, 2 is a condensing lens, and 3 is a sample to be measured, such as a thin A spot developed on layer chromatography (TLC) plate 4,
A condensing lens 2 condenses the light from the light source 1 onto a spot 3. Although the light source 1 is arranged for transmission, a reflection light source (not shown) may alternatively or additionally be provided.

The transmitted or reflected light from the sample spot 3 (image 3' of the spot 3) is imaged by the imaging lens 5 onto the entrance slit 6 of the spectrometer. The light from the measurement target portion of the spot image 3' is transmitted through the entrance slit 6.
The light passes through the concave diffraction grating 7 and is separated into spectra.

Different wavelengths λ ₁ separated by the diffraction grating 7,
Since the slit images 6λ _{1 and} 6λ ₂ due to λ 2 are formed on the spectral image plane 8, measurement can be performed by placing a detector on this plane 8. In this case, to perform two-wavelength photometry, for example, two detectors 9λ ₁ and 9λ ₂ are placed at desired wavelength positions on the spectral image plane 8, and to select two wavelengths, each detector is placed at a desired wavelength position. What is necessary is to displace it in the spectral direction (lateral direction) on the spectral image plane 8.

By the way, when two solid-state image sensors are used as the above-mentioned detectors and they are arranged within the spectrum of the same order, the physical or mechanical width dimensions of the detectors cause both detectors to be closer to each other than a certain distance. This results in the inconvenience that the selection range of two wavelengths is limited.

In other words, in the case of a one-dimensional photodiode array, which is common as a solid-state image detector, the width is 8 mm.
Although there is a certain degree of Wavelengths that can be detected by one detector) λ ₁ and λ ₂ cannot be closer to each other than 80 nm. In dual wavelength photometry, the two wavelengths are 5nm.
In some cases, it may be necessary to bring them close to each other, so the above-mentioned restrictions are important in practice.

In order to solve this problem, the present invention arranges two detectors so that they can be displaced in the spectral direction within wavelength regions of different orders on the spectral image plane.

Hereinafter, an embodiment will be described with reference to FIG. 2. In FIG. 2, the same reference symbols as in FIG. 1 indicate corresponding elements, and the explanation will be omitted.

S ₀ is the O-order spectrum due to the diffraction grating of the light passing through the slit, S ₊₁ is the +1st-order spectrum, and S _-1 is -1
This is the following spectrum. The solid-state image detectors 9λ ₁ and 9λ ₂ each have a +1st order spectrum S ₊₁ on their light receiving surfaces.
and is displaceable in the wavelength dispersion direction within the range of the -1st order spectrum S _-1 .

To change the wavelength λ ₁ or (and) λ ₂ , the detector 9λ ₁ or (and) 9λ ₂ may be displaced in the wavelength dispersion direction within the respective spectra.

The detectors 9λ ₁ and 9λ ₂ can also be arranged in spectra of different orders other than the above-mentioned orders.

As described above, according to the present invention, since the two detectors are disposed so as to be displaceable in the spectral direction within spectra of different orders on the spectral image plane, there is no limit to the distance between two wavelengths that can be brought close to each other. This has the effect of widening the selectivity of the analysis sample.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a densitometer using a solid-state image detector, and FIG. 2 is a schematic diagram of an embodiment of the present invention. 2...Condensing lens, 3...Sample spot, 4...
... TLC plate, 5 ... Imaging lens, 6 ... Entrance slit, 6' ... Slit image, 7 ... Diffraction grating, 8 ... Spectral image plane, 9λ ₁ , 9λ ₂ ... Solid-state image detector, S ₀ ...Oth order spectrum, S ₊₁ ...
...+1st order spectrum, S _-1 ...-1st order spectrum.

Claims (1)

[Claims] 1. A densitometer consisting of an entrance slit where an image of the sample is formed based on the irradiated light, a spectroscopic element that spectrally spectra the light that has passed through the entrance slit, and a pair of solid-state image detectors that each detect the spectroscopic light. A densitometer, wherein the detector is disposed so as to be displaceable in the spectral direction within spectra of different orders on the spectral image plane of the spectral element.