JPH09311073A - Wavelength scanning spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wavelength scanning spectroscope in which the movement accuracy of an exit slit is increased without sharply increasing its costs, and by which a spectroscopic analysis can be performed with high accuracy. SOLUTION: An exit slit 18 which is installed before a photodetector is supported by a bar 19 which can be rocked around a fulcrum shaft 21. A rocking mechanism 20 which can rock the bar 19 is connected to a part at a distance from the fulcrum shaft 21 at the bar 19. The exit slit 18 is supported in a position which is close to the fulcrum shaft 21 from its connection part. As a result, the driving amount of the rocking mechanism 20 is reduced and transmitted to the side of the exit slit 18 by the action of a lever.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength scanning spectroscope, and more particularly, to a mechanism portion for laterally moving an exit slit with respect to diffracted light in front of a photodetector.

[0002]

2. Description of the Related Art In general, a wavelength scanning spectroscope is used in an ICP emission spectroscopic analyzer using a high frequency inductively coupled plasma as a light source, other emission spectroscopic analyzers, and a spectrophotometer.

In this wavelength scanning spectroscope, the radiated light from the sample is dispersed into a spectrum light of each wavelength by a diffraction grating, and a specific spectrum light among them is selected and detected to determine the qualitative characteristics of the elements contained in the sample. Perform quantitative analysis.

As a conventional example thereof, FIG. 5 shows the configuration of a Zerniter type wavelength scanning spectroscope. In the figure, reference numeral 1 is
With a sample light source such as a plasma torch, the emitted light from the light source 1 is condensed by a condenser lens 2 and enters the housing 3, and an entrance slit 4, two concave mirrors 5, 6, a diffraction grating 7, Through the exit slit 8 it is guided to a photodetector 9 such as a photomultiplier.

The diffraction grating 7 is provided with a rotating mechanism 10 including a pulse motor and a combination of a pulse motor and a worm wheel. The rotating mechanism 10 changes the angle of the diffraction grating 7. Further, the exit slit 8 is provided with a moving mechanism 11 for moving the exit slit 8 laterally with respect to the incident light.

Conventionally, this moving mechanism 11 is a combination of a pulse motor 12 and a screw shaft 13, as shown in FIG. 6, and converts the rotation of the pulse motor 12 into a linear motion to directly output the exit slit 8. Is designed to be moved laterally. In the figure, reference numeral 14 is a female screw shaft screwed into the screw shaft 13, and 15 is a support base slidably supporting the outlet slit 8.

[0007]

In order to select and detect a specific spectrum light by wavelength scanning with this type of spectroscope,
The angle of the diffraction grating 7 is changed by the rotating mechanism 10,
In front of the photodetector 9, the lateral position of the exit slit 8 is adjusted by the moving mechanism 11. However, when this spectroscope is used in an emission spectroscopic analyzer, the peak of the spectrum light to be measured must be sharp. Therefore, it is necessary to set the wavelength angle in units of seconds. Therefore, not only the rotation angle of the diffraction grating 7 is set with high accuracy, but also the exit slit 8
It is necessary to perform the lateral movement of the with high accuracy.

However, the conventional exit slit moving mechanism 1
Since 1 has the above-described configuration, in order to improve the accuracy of movement, the pitch of the screw of the screw shaft is made fine to reduce the movement amount per one rotation, or the number of rotation divisions of the pulse motor 12 is increased. However, it is not easy to realize, and even if it can be realized, the cost will be significantly high.

In view of the above-mentioned conventional problems, the present invention increases the movement accuracy of the exit slit and enables accurate spectroscopic analysis by adding a relatively simple structure without significantly increasing the cost. The task is to do so.

[0010]

In order to achieve the above-mentioned object, the present invention provides a wavelength scanning spectroscope in which an exit slit is provided in front of a photodetector so as to be laterally movable,
An outlet slit supporting bar that can swing along the moving direction of the outlet slit around the fulcrum shaft, and a swinging mechanism that swingably drives the bar in association with a portion of the bar that is distant from the fulcrum shaft. In addition, the outlet slit is supported on the bar at a position closer to the fulcrum shaft than the bar linkage part of the swing mechanism.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail with reference to the drawings. FIGS. 1 and 2 show an outlet slit moving mechanism according to an embodiment of the present invention. FIG.
FIG. 2 is a plan view.

In these drawings, reference numeral 16 indicates the entire exit slit moving mechanism, 17 is a concave mirror at the rear stage, and 18 is a concave mirror.
Is an exit slit provided in front of a photodetector (not shown). This exit slit moving mechanism 16 is included in the wavelength scanning spectroscope as already shown in FIG. 5, and since the part except the exit slit 18 and its moving mechanism 16 is not different from the conventional one, The structure of the part is self-explanatory and will not be described.

The outlet slit moving mechanism 16 comprises a bar 19 for supporting the outlet slit 18, and a swing mechanism 20 linked to the bar 19. The bar 19 is arranged in parallel with the optical path of the light incident on the photodetector, and is supported by a fulcrum shaft 21 so as to be swingable around the vertical axis. In this example, the outlet slit 18 is erected at one end of the bar 19 and the fulcrum shaft 21
Is set at a position close to the exit slit 18 in the middle of the bar 19 in the longitudinal direction.

The swinging mechanism 20 is located on one side of the portion of the bar 19 opposite to the outlet slit 18, and pushes the side surface of the bar 19 to move the bar 19 to the fulcrum shaft 21. It swings around. This swing mechanism 20
Is a pulse motor 22, a screw shaft 23 that rotates integrally with the drive shaft thereof, and a female screw shaft 24 that is screwed onto the screw shaft 23.
And a bracket 25 that holds the female screw shaft 24 so that it can slide in the axial direction but does not rotate, and the tip of the female screw shaft 24 abuts the side surface of the bar 19 at a substantially right angle. A tension spring 26 is provided between one end of the bar 19 and the housing-side fixed portion.
The spring 26 keeps the side surface of the bar 19 and the tip of the female screw shaft 24 in contact with each other.

The linking position between the swinging mechanism 20 and the bar 19, that is, the contact position between the female screw shaft 24 and the bar 19, is set at a position apart from the fulcrum shaft 21.
The distance b from the linkage position to the fulcrum shaft 21 is equal to the fulcrum shaft 2
It is longer than the distance a from 1 to the exit slit 18 (a
<B) is set.

In the above structure, when the female screw shaft 24 is projected by the rotation of the pulse motor 21 in one direction, the bar 19
When the side surface is pushed, it swings in the counterclockwise direction in the figure, whereby the exit slit 18 at the other end of the bar 19 laterally moves with respect to the incident light on the photodetector.

In this case, the bar 19 is a lever that uses the portion linked to the swinging mechanism 20 as a force point and the attachment position of the outlet slit 18 as a point of action to reduce the amount of movement of the female screw shaft 24 and to the outlet slit 18 side. And tell this bar 1
9, the lateral movement amount of the outlet slit 18 is reduced to a / b which is the protruding amount of the female screw shaft 24. Therefore, even if the precision of the mechanism such as the pulse motor 22 and the screw directly connected to the pulse motor 22 is similar to the conventional one, the movement resolution of the exit slit 18 is improved by b / a times, and the lateral accuracy of the exit slit 18 is high. It becomes possible to move.

As in the above embodiment, the side surface of the bar 19 is pushed by the tip portion (female screw shaft 24) of the swinging mechanism 20, and the tension spring 26 keeps the contact state. When the rocking mechanism 20 and the rocking mechanism 20 are linked to each other, there is no play between the rocking mechanism 20 and the rocking mechanism 20 and the movement of the rocking mechanism 20 is caused by the bar 19.
It is transmitted without rattling. In order to link the bar 19 and the rocking mechanism 20 to each other, the bar 19 and the rocking mechanism 20 are additionally provided.
May be directly engaged with the tip portion (for example, the female screw shaft 24). In that case, it is not necessary to provide a tension spring.

In the above embodiment, the bar 19 is used.
Although a mechanism using a screw shaft is shown as the swinging mechanism 20 for swinging the, the mechanism is not limited to this.
For example, a mechanism in which a pulse motor and a cam are combined may be used to bring the cam into contact with the side surface of the bar.

FIG. 3 shows another embodiment.
In this embodiment, a fulcrum shaft 21 is set at one end of the bar 19, and a linking portion with the swing mechanism 20 is set at the other end. The outlet slit 18 is provided between the linking portion and the fulcrum shaft 21. By being supported, the distance a from the fulcrum shaft 21 to the outlet slit 18 is shorter than the distance b from the fulcrum shaft 21 to the linking portion with the swing mechanism 20. In this example, it is sufficient that the length of the bar 19 is about the distance b.
Is shorter than that of the embodiment shown in FIG. 1, and the required space can be reduced.

FIG. 4 shows still another embodiment. In this embodiment, the bar 19 is divided into an action point side portion 19A and a force point side portion 19B. Then, the fulcrum shaft 21 penetrates the outer wall 27 of the housing inward and outward, and at the inner portion of the fulcrum shaft 21, a portion 19A of each portion of the bar 19 on the action point side that supports the outlet slit 18.
Is attached, and the swing mechanism 20 is attached to the outer side of the fulcrum shaft 21.
Is attached to the power point side portion 19B.
In this configuration, the portion that swings and drives the bar 19 is arranged outside the housing, and the configuration inside the housing is simplified.

[0022]

According to the present invention, the driving amount of the swinging mechanism composed of the screw shaft or the like is reduced by the action of the lever so that the exit slit is moved laterally. Compared to the conventional moving type, the moving resolution is increased by the ratio of the lever, and the exit slit can be moved laterally with high accuracy.

In this case, mechanically, only by providing a bar serving as a lever, there is no need to make a heavy-duty modification such as making the screw pitch finer or increasing the number of rotation divisions of the pulse motor. It can be implemented cheaply.

[Brief description of drawings]

FIG. 1 is a perspective view of an outlet slit moving mechanism according to an embodiment of the present invention.

FIG. 2 is a plan view of the moving mechanism.

FIG. 3 is a plan view of a moving mechanism according to another embodiment of the present invention.

FIG. 4 is a vertical sectional side view of a moving mechanism according to still another embodiment of the present invention.

FIG. 5 is a configuration diagram of a wavelength scanning spectroscope.

FIG. 6 is a side view of a conventional exit slit moving mechanism.

[Explanation of symbols]

 18 outlet slit 19 bar 20 swing mechanism 21 fulcrum shaft 22 pulse motor 23 screw shaft

Claims (1)

[Claims] 1. A wavelength scanning spectroscope in which an exit slit is provided in front of a photodetector so as to be movable laterally, and the exit is capable of swinging along a moving direction of the exit slit around a fulcrum axis. A bar for slit support and a swinging mechanism that swings the bar in association with a portion distant from the fulcrum axis of the bar are provided. At a position closer to the fulcrum axis than the bar linking portion of the swinging mechanism. A wavelength scanning spectroscope characterized in that an exit slit is supported on the bar.