JPS6337885B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-scanning spectroscopic device that can measure spectra in a certain wavelength range at once.

A diode array element has several hundred photodiodes lined up at 1/1000 inch intervals, so for example
When a spectral image in the range of 200nm to 600nm is focused on the range of 400 elements of a diode array, 1n
This means that the spectroscopic spectrum can be measured with a wavelength resolution of m. On the other hand, when a diffraction grating is used as a spectroscopic element, one point on the spectral image plane contains light of one wavelength and light of an integer fraction of that wavelength (secondary light, third-order light, etc.).
Tsugumitsu etc.) are coming. For example, from 200nm to 600nm
If we take the spectrum in the range of , 250 nm light comes as secondary light at the 500 nm position. These high-order lights are a nuisance and must be filtered out. Width ΔS of spectral image for unit wavelength difference Δλ
If a spectral image is formed so that it is sufficiently large, even if a filter is placed in the front of the spectral image in the range where higher-order light exists, the width of the disturbance in the refraction of light at the edge of the spectral image can be calculated as the spectral width ΔS for a unit wavelength difference. There is no problem because it can be made smaller, but if you use a diode array and try to make one element correspond to a unit wavelength difference, the width of the spectral image becomes narrower. Disturbance of the spectral image due to light refraction cannot be ignored. Therefore, the present invention was made with the object of eliminating the interference of higher-order light when measuring the entire spectral image using an array.

In the present invention, a filter is installed in and out of the optical unit of a spectrometer, and is linked to the readout operation of the array, so that the filter is placed in the optical path of the spectrometer only while reading out the wavelength range where higher-order light overlaps. The object of the present invention is to provide a non-scanning spectroscopic device in which light in a wavelength range corresponding to higher-order light is removed by inserting the light into the light source. The present invention will be explained below with reference to Examples.

FIG. 1 shows an embodiment of the present invention. Reference numeral 1 is an incandescent light bulb serving as the first light source, which is responsible for the visible light range, and reference numeral 2 is a deuterium lamp, which is responsible for the ultraviolet light range. Since the deuterium lamp has a through hole passing through the center of the electrode, the light from the incandescent bulb 1 at the rear is sent to the spectrometer through this through hole. 3 is a concave mirror for focusing, and 7 is an entrance slit of the spectrometer. The concave mirror 3 collects the light from the light sources 1 and 2 onto the entrance slit 7. 6 is a sample. The light transmitted through the sample 6 is incident on the concave diffraction grating 8 through the slit 7 and is separated by the concave diffraction grating 8 to form the absorption spectrum of the sample 6 on the diode array 9. Reference numeral 5 denotes a rotating filter plate, which is rotated by a pulse motor 4.

Diode array 9 has a pitch of 1/1000 inch.
It consists of 512 photodiodes lined up, of which 401 elements are used to form a spectral image in the wavelength range of 200 nm to 600 nm. FIG. 2 shows how the secondary and tertiary lights overlap in this spectral image. Due to the characteristics of the light source, there is no light with a wavelength of 150 nm or less.
Therefore, no filter is required while reading spectral data of 200 to 300 nm from the array.
While reading spectral data in the range of 300 to 400 nm, a bandpass filter having a transmission range of 300 to 400 nm may be used. For the range of 400 to 600 nm, a low pass filter that cuts out wavelengths of 300 nm or less may be used. Figure 3 shows the relationship between the reading wavelength range of spectral data on the array and the characteristics of the filter used.
is used, and Toshiba Kasei UV-35 is used as a low pass filter with a readout range of 400 to 600 nm. These filters are mounted on the filter plate 5 of FIG. Figure 4 shows this filter plate 5.
In the front view, each filter 11, 12 is sector-shaped and each occupies an angular area of 120°. 11 is a band pass filter for the readout range of 300 to 400 nm, 1
2 is a low pass filter for a readout range of 400 to 600 nm.

The rotating filter plate 5 rotates once every 150 msec. FIG. 5 shows the readout schedule for the diode array. One scan of the array is divided into three times,
Each read operation is started by the falling edge of the start pulse that is emitted at a period of 50 msec.
From No. 400 to No. 400, and in the third section, No. 401 to No. 512 are read. The filter plate rotates once every 150 msec, and the first segment of the array scan is being performed.50
For m seconds, there is no filter, and for the second segment of 50 m seconds, the filter 11 is in front of the inlet slit 7.
Filter 12 is in slit 7 for 50 msec of segment.
It appears to be located in front of the Data read from array 9 is stored in memory.

When measuring the spectrum formed on an array element, the present invention does not read out the entire output of the array element by a continuous readout operation, but divides the array element into a plurality of parts in the direction in which unit elements are arranged. The first feature is that the readout operation is performed separately for each section, and by doing this, while reading out one section, orders other than the diffraction order to be measured in that section can be detected. A filter with uniform characteristics (characteristics do not vary depending on location) that blocks diffracted light is placed in front of the array element, making it possible to replace the filter in synchronization with the switching of readout sections. Therefore, the position of the filter in the light traveling direction on the spectrum measurement optical path is not limited to the vicinity of the entrance slit. It is necessary that one type of filter occupies the entire cross-section of the measuring beam path during the readout of a section.
In other words, this prevents the transmitted light from a plurality of types of filters from being projected onto the section being read. By doing so, the following effects can be obtained. Furthermore, in the above-described embodiment, the filters are replaced by continuously rotating the filters arranged on a disk, but the filters may also be replaced dynamically in conjunction with the segmented reading of the array elements. Needless to say, it's a good thing.

As shown in Fig. 6, when a filter F is placed in front of a spectral image S, the spectral image is disturbed at a width d due to reflection and refraction of light at the edge e of the filter F, and the width d depends on the thickness of the filter. 0.1×
It will be about a few mm. As mentioned above, the diode array has a width of about 1/1000 inch = 25μ per element, and if this width corresponds to a wavelength difference of 1 nm, the disturbance width d is 0.25.
Spectrum disturbance occurs within a range of about 10 nm even if the distance is mm, and the high resolution of the diode array cannot be utilized. According to the present invention, since the filter is inserted across the entire optical path of the spectrometer, the influence of the edges of the filter is eliminated, and high-resolution spectrum measurement can be performed using a diode array.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an apparatus according to an embodiment of the present invention, and FIG.
The figure is a graph showing the degree of overlap of secondary and tertiary light in the spectroscopic spectrum. Figure 3 is a graph showing the relationship between the spectroscopic spectrum and the characteristics of the filter used.
The figure is a front view of the rotating filter plate, FIG. 5 is a time chart of the operation of the apparatus of FIG. 1, and FIG. 6 is an enlarged view showing the edge effect when the filter is placed in front of the spectral image. 1, 2... Light source, 6... Sample, 7... Inlet slit, 5... Rotating filter plate, 8... Concave diffraction grating, 9... Diode array.

Claims (1)

[Claims] 1. In a device configured to form a spectral image using a diffraction grating on a light-receiving element in which unit minute elements such as diode arrays are arranged at regular intervals and the output of each unit element is sequentially read out, the array element is The array element is divided into a plurality of sections in the array direction, and the output of each unit element of the same array element is read out separately for each section, and while reading out one section, the diffraction to be measured in that section is A plurality of types of filters are replaceably arranged on the spectrum measurement optical path so that only the transmitted light of a filter having uniform characteristics in a location that blocks diffracted light wavelengths of orders other than the order is projected onto the array element. . A spectroscopic measuring device, characterized in that the filter is replaced in conjunction with the divisional readout of the array element output.