JPH07140004A - Spectroscopic analysis apparatus - Google Patents

Abstract

PURPOSE:To prevent beforehand a needless light from entering a spectroscopic chamber by providing, between a light source and an inlet slit, an inputting light-limiting means having an opening of which width in a direction perpendicular to a rotational axis of a grating can be varied in accordance with an angle of the grating. CONSTITUTION:A grating 16 is placed on an initial angle position and right and left frame plates of an inputting light-limiting plate 23 are placed on prescribed initial positions. An optical system having a lens 20 is set such that a measurement light from a light source 21 passing through an opening section of the limiting plate 23 is emitted on an area slightly wider than that of the grating 16 placed on the initial angle position. By operating a measurement- starting button connected to a control section, the angle grating 16 and the positions of the right and left frame plates are controlled along a prescribed program. A light that may enter a spectroscopic chamber 11 when the limiting- plate does not exist is blocked before entering the spectroscopic chamber 11 so that the light need for irradiating the grating 16 is inputted there. A stray light in the spectroscopic chamber 11 is reduced so that the measurement accuracy is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emission spectroscopy analyzer and an absorption spectroscopy analyzer.

[0002]

2. Description of the Related Art A spectroscopic analyzer is a spectroscope for separating the light generated by a sample heated to a high temperature or the light absorbed by a sample by a specific absorption line, and detecting the intensity of each wavelength. Is an apparatus for analyzing a sample by. An emission spectroscopic analysis device will be described with reference to FIG. 5 as an example of a conventional spectroscopic analysis device. The light generated by the light emitting source 21 such as the heated sample is condensed by the condenser lens 20 in the entrance slit 19 of the spectroscopic analyzer. The light that has passed through the entrance slit 19 and entered the spectroscope chamber 11 has the first reflecting mirror (concave mirror) 1
It is collimated by 8 and sent to the grating 16. The grating 16 separates the incident light for each wavelength and reflects it. Of the reflected light, only a specific wavelength component determined by the position of the exit slit 13, the angle of the second reflecting mirror (concave mirror) 12 and the angle of the grating 16 is focused on the exit slit 13. The intensity of the light passing through the exit slit 13 is detected by the photodetector 14. Therefore, by rotating the grating 16 about the axis 17 passing through the surface center of the grating 16,
The wavelength of the light passing through the exit slit 13 can be scanned, whereby the wavelength intensity distribution of the light generated by the light emission source 21 can be measured.

[0003]

In order to carry out the analysis with high accuracy, it is desirable to utilize as much light as possible from the light emitting source 21. Therefore, in the conventional spectroscopic analyzer, the grating 16 when viewed from the first reflecting mirror 18
The optical system is configured so that the light from the light emitting source 21 illuminates a slightly wider range than the entire surface of the grating 16 when the maximum angle of view is maximized. That is, so that unnecessary light other than that is absorbed when it is applied to the holding plates 15 of the first and second reflecting mirrors 18 and 12 and the grating 16, the light is absorbed in the portions outside the necessary range. The agent was being applied.

Here, although the first and second reflecting mirrors 18 and 12 are fixed, the angle of the grating 16 must be changed depending on the measurement wavelength. Therefore, FIG.
As shown in FIG. 5, when the light is irradiated in a range that is slightly wider than the entire surface of the grating 16, the grating 16 rotates, and as shown in FIG. A lot of light will illuminate the outside of the grating 16. Of course, holding plate 1
A light absorbing agent is applied to the surface around the grating 16 of No. 5, but since the light absorbing agent does not completely absorb the light, the light once entering the spectroscope chamber 11 is internally The light is scattered and part of it passes through the exit slit 13 as stray light and is detected by the photodetector 14.

The present invention has been made to solve such a problem, and an object of the present invention is to preliminarily store unnecessary light, which changes according to the state of the spectroscope, inside the spectroscope chamber 11. The object of the present invention is to provide a spectroscopic analyzer capable of performing highly accurate analysis by keeping it from entering.

[0006]

SUMMARY OF THE INVENTION In the present invention made to solve the above problems, light from a light emitting source is introduced into a spectroscope chamber through an entrance slit, and a grating is rotated around a predetermined axis in the spectroscope chamber. Rotate to, and perform wavelength scanning by changing the angle, in the spectroscopic analyzer for measuring the wavelength intensity distribution of the light, arranged between the emission source and the entrance slit, depending on the angle of the grating, It is characterized in that it is provided with an incident light limiting means having an opening whose width changes in a direction perpendicular to the rotation axis of the grating.

[0007]

The relationship between the width of the opening of the incident light limiting means and the angle of the grating is determined in advance so that the light passing through the opening of the incident light limiting means always illuminates a range slightly wider than the entire width of the grating. Keep it. This prevents unnecessary light from entering the spectroscope chamber, and prevents deterioration of analysis accuracy due to stray light.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An emission spectroscopic analyzer according to an embodiment of the present invention will be described with reference to FIGS. Although the basic configuration of the emission spectroscopic analyzer of this embodiment is the same as that of the conventional device shown in FIG. 5, the emission source 21 and the condenser lens 2 are used in the device of this embodiment.
The incident light limiting means 23 is arranged between 0 and 0. The incident light limiting means 23 used in this embodiment is composed of four frame plates 31, 32, 33, 34 as shown in FIG. 2, and the upper and lower frame plates 31, 32 are fixed, and the left and right frame plates 33. , 34 can be moved left and right by screws 36, 37. The screws 36 and 37 are mutually opposite screws, and by rotating the screws 36 and 37 with a motor 38, the left and right frame plates 33 and 34 move in the opposite direction in synchronization.

The motor 38 is connected to the control unit 40 of the present optical emission spectroscopic analyzer and rotates according to the command. The control unit 40 is also connected to a motor 39 for rotating the grating 16, and the control unit 40 drives both the frame plate moving motor 38 and the grating rotating motor 39 in synchronization.

When the power switch of the present emission spectroscopic analyzer is turned on, the control unit 40 performs a predetermined initialization process in which the grating 16 is set to a predetermined initial angular position and the left and right frame plates 33 are set. , 34 in a predetermined initial position. At this time, the upper, lower, left and right frame plates 31 of the incident light limiting means,
The measurement light from the light emission source 21 that has passed through the opening 35 formed by 32, 33, and 34 illuminates a slightly wider range than the grating 16 at the initial angular position. Measurement start button 4 connected to the control unit 40
When 1 is operated, the controller 40 drives the grating rotating motor 39 and the left and right frame plate moving motor 38 according to a predetermined program. This program is designed for the optical system including the lens 20 so that the light passing through the opening 35 of the incident light limiting means 23 always illuminates a slightly wider range than the entire surface of the tilted grating 16 at that time. It is calculated at the time and is preset. As a result, as shown by the dotted line in FIG. 1, the light entering the spectroscope chamber 11 when the incident light limiting means 23 is absent, before entering the spectroscope chamber 11 by the incident light limiting means 23 in this embodiment. (The incident light limiting means 23 may be placed between the condenser lens 20 and the entrance slit 19) and only the light necessary for illuminating the grating 16 enters the spectroscope chamber 11 as shown by the solid line. enter. Therefore, the stray light in the spectroscope chamber 11 is reduced, and the measurement accuracy is increased.

Another example of the incident light limiting means is shown in FIG. In this example, the incident light limiting means 24 is composed of a frame 42 provided with an opening 43 and rotatable by a motor 44. By rotating the frame 42 with the motor 44, the width of the opening when viewed from the light emitting source (or the absorbing light source) (that is, the projection width of the opening 43 on the plane perpendicular to the optical axis) is changed (FIG. 3).
(B)).

In order to further improve the measurement accuracy, it is desirable to consider that the focal length of the lens 20 changes depending on the wavelength. That is, if the size of the opening of the incident light limiting means 23 is determined irrespective of the wavelength, the range of the light flux that illuminates the grating 16 changes due to the change in the focal length. In this case, the size of the light flux needs to be changed not only in the left-right direction (direction perpendicular to the rotation axis of the grating) but also in the up-down direction (direction parallel to the rotation axis of the grating). Therefore, when the change in the focal length of the lens 20 depending on the wavelength is taken into consideration, the incident light limiting means that can change the vertical and horizontal widths is used. An example thereof is shown in FIG. The incident light limiting means 25 is a frame 46 that can be rotated about two axes by a motor 48 and a motor 49, and the projection width of the opening 47 on a plane perpendicular to the optical axis is changed by both the motors 48 and 49. That is, the width of the opening in the direction perpendicular to the grating rotation axis is set by the motor 48 according to the rotation angle of the grating, and is parallel to the grating rotation axis according to the change in the focal length of the measurement wavelength that changes accordingly. The width of the opening in any direction
Change with. Of course, similarly to the example shown in FIG. 2, the upper limit frame plate may be changed by a motor and a screw.

[0013]

The spectroscopic analyzer according to the present invention can be set so that the light passing through the opening of the incident light limiting means always illuminates a range slightly wider than the entire width of the grating. This prevents unnecessary light from entering the spectroscope chamber, and prevents deterioration of analysis accuracy due to stray light.

[Brief description of drawings]

FIG. 1 is a plan view showing a schematic configuration of an emission spectroscopic analysis apparatus that is an embodiment of the present invention.

FIG. 2 is a side view showing a configuration of a parallel movement type limiting plate which is a first example of incident light limiting means.

FIG. 3 is a front view (a) showing a configuration of a rotary limiting plate which is a second example of incident light limiting means, and a plan view (b) showing the operation thereof.

FIG. 4 is a front view showing the configuration of a biaxial rotation type limiting plate which is a third example of incident light limiting means.

FIG. 5 is a plan view showing a schematic configuration and operation of a conventional emission spectroscopy analyzer.

[Explanation of symbols]

11 ... Spectrometer room 12 ... 2nd reflecting mirror 13 ... Exit slit 14 ... Photodetector 15 ... Grating holding plate 16 ... Grating 17 ... Grating rotating shaft 18 ... 1st reflecting mirror 19 ... Entrance slit 20 ... Condensing lens 21 ... Light source 23, 24, 25 ... Incident light limiting means 31, 32 ... Upper and lower frame plates 33, 34 ... Left and right frame plates 35 ... Openings 36, 37 ... Screws 38 ... Left / right frame plate moving motor 40 ... Control part 41 ... Measurement Start button

Claims (1)

[Claims] 1. Light from a light-emitting source is introduced into a spectroscope chamber through an entrance slit, a grating is rotated around a predetermined axis in the spectroscope chamber, and the angle is changed to perform wavelength scanning. In the spectroscopic analyzer for measuring the wavelength intensity distribution of the incident light, which is arranged between the light emitting source and the entrance slit and has an opening whose width changes in the direction perpendicular to the rotation axis of the grating depending on the angle of the grating. A spectroscopic analysis apparatus comprising a light limiting unit.