JPS58131520A - Spectral device - Google Patents

Abstract

PURPOSE:To facilitate to work by eliminating the use of curve guide and to obtain a spectral device having high accuracy as a whole, by keeping the relation toward the grating center always, when an exit slit is moved along the Rowland circle which is supposed. CONSTITUTION:A straight guide T passes the center of an incident slit S1 and is turnable by making a shaft vertical to the paper surface expressed by a figure as the fulcrum. An exit slit S2 is slidable on a guide in the state that its surface is inclined with an angle theta against the guide T. The angle theta is constant, and while the slit S2 moves on the Rowland circle R, its surface is faced always toward the center of a diffraction grating G.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spectroscopic device that uses a diffraction grating and has a Rowland circle, and particularly relates to a slit drive mechanism in the spectroscopic device.

When a spectrometer using a concave diffraction grating drives the exit slit during wavelength scanning, the spectral image plane is curved along a Rowland circle, and the exit slit must be driven along this spectral image plane. , and the exit slit surface is preferably perpendicular to the line connecting the center of the diffraction grating and the center of the exit slit, that is, the main diffraction ray. A driving mechanism for the exit slit that satisfies such requirements is complicated. Therefore, the present invention was made with the object of simplifying the driving mechanism for such an exit slit.

First, the object of the present invention will be explained in more detail with reference to FIG. Figure 1 shows an off-plane Eagle type spectrometer, with 8
1 is an entrance slit, G is a concave reflection diffraction grating, and R is a Rowland circle. The entrance slit S1 is located on the Rowland circle R, and the diffraction grating G is in contact with the Rowland circle. ○
is the center of the Rowland circle. The spectral image is formed along the Rowland circle R, and the spectral image of light having a wavelength near the blaze wavelength of the diffraction grating G is formed in a range close to the entrance slit S1.

The exit slit stays in the Rowland circle as the wavelength scans.■
However, in order to avoid collision with the entrance slit, the positions of both are shifted in the direction perpendicular to the plane of the drawing. The present invention is directed to a mechanism that provides such movement of the exit slit.

Although an off-plane Eagle type spectrometer was used in the explanation above, the present invention is applicable to general spectroscopic devices in which a slit needs to be moved in response to a moving Rowland circle.

An example of a conventional mechanism for providing slit movement as described above is shown in FIG. Reference numeral B denotes a substrate, which is pivoted at the center of rotation 11 and can rotate within the plane of the figure. 1 is a first gear attached to the motor shaft, and 2 is a second gear meshing with the first gear, which is centered around the rotation center 11 of the board B and is loosely fitted to the rotation axis of the board B. A third gear 3 meshes with the second gear 2 and is pivotally attached to the board B. The second gear 2 is the board 1
1, the meshing relationship between the third gear and the second gear does not change even if the substrate B rotates. Board B
In the figure, 10 is an arcuate projection-shaped guide having the same curvature as the Roland circle and passing over the rotation center ll. A slit unit 9 straddles the guide 10 and is slidable along the guide. 6 is attached to the board B by a feed screw approximately parallel to the guide 10, and the third gear 3 connects the bevel gears 4,
5. Numeral 7 is a nut screwed onto a feed screw and pushes a bar 8 protruding from the slit unit 9. With this configuration, when the first gear 1 is rotated, the slit unit 9 can be moved along the guide 10. In this mechanism, the guide 10 is an arc with the same curvature as a Rowland circle, so it is difficult to work with.Also, since the slit unit slides along this curved guide, it is more prone to wobbling than in the case of a straight guide, and the precision is It is difficult to obtain good equipment. Further, the slit unit has a certain relationship with the tangential direction of the guide 10, and the normal line of the slit surface does not point toward the center of the diffraction grating except at a specific position, which is an optical problem.

The present invention attempts to eliminate such drawbacks of the conventional example.

FIG. 3 is a diagram explaining the present invention in detail. Sl is an entrance slit, and G is a diffraction grating. T is the entrance slit Sl
It is a linear guide that can be rotated about an axis that passes through the center of the figure and is perpendicular to the plane of the drawing. It is possible. The angle θ is constant. The output sleeve) is driven by a mechanism (not shown) as the guide TK& and the guide is rotated about its fulcrum.
The center of EI2 can be moved along the Rowland circle R. Under such a relationship, the angle ψ between the guide T and the straight line connecting the center of the grating G and the center of the output slit S2 at any position of the output slit S2 as shown in the figure is on the chord 51-G in the circle R. Since it is a circumferential angle extending over , it is constant regardless of the position of S2. The surface of the output slit S2 is inclined by θ with respect to the guide T, and since θ is constant, ψ10 is also constant, and θ can be set so as to be at a right angle of ψ+θ−. By doing so, the exit slit S2 can always direct its surface toward the center of the diffraction grating G while moving on the O-land circle R. Considering the case where the output slit passes over the input slit and reaches position S2' in the figure, in this case the linear guide is located at T1 and the external angle of the circumferential angle of chord 5l-G is ψ. The relationship that the 5210 plane faces the center of the lattice G is maintained. The above is the principle of the present invention.

FIG. 4 shows an embodiment of the present invention. B is the board and the fulcrum 11
It can be rotated within the plane of the diagram around . The fulcrum 11 passes through the center of an elongated entrance slit (not shown) in a direction perpendicular to the plane of the drawing. An arm 12 protrudes from the board B, and its tip engages with a nut 14' screwed onto the feed screw 13. By rotating the feed screw 13 with a motor (not shown), the board B is moved to the fulcrum 11. It can be rotated around. The substrate B is provided with a linear guide 14 and a feed screw 6 parallel to the linear guide 14. Reference numeral 9 denotes an output slit unit which is screwed onto the feed screw 6 and abuts against the guide 14;
The rotation of the feed screw 6 causes the guide 14 to move. An output slit 82 is attached on the slit unit 9.

The surface of the output slit S2 is attached to the feed screw 6 so as to be inclined at an angle θ. The movement locus of the center of the output slit S2 is parallel to the feed screw 6 and corresponds to the guide T in FIG. 3. The feed screw 6 is rotated by a motor (not shown) via a gear 15 and bevel gears 4 and 5. The center of the rotation axis of the bevel gear 4 coincides with the fulcrum of the board B, and even if the board B is rotated, the rotation can be transmitted to the feed screw 6 without any problem. The motors driving the feed screws 6 and l/ are different and are each driven by pulses. By predetermining the relationship between the number of pulses given to each motor and controlling it by a computer, the exit slit S2 can be moved along an assumed Rowland circle.

The spectroscopic device of the present invention has the above-described configuration, and since a curved guide is not required, it is easy to work and can easily obtain high accuracy, and a spectroscopic device with little mechanical rattling and high accuracy as a whole can be obtained. Moreover, the normal to the slit surface can be automatically and always directed toward the center of the diffraction grating without using any special mechanism.

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[Brief explanation of the drawing]

Fig. 1 is a schematic plan view of an off-plane Eagle type spectrometer, Fig. 2 is a plan view of a conventional device, Fig. 3 is a plan view showing the principle of the present invention, and Fig. 4 is a schematic diagram of an embodiment of the device of the present invention. FIG. Sl...Incidence slit, S2...Output slit, G
...Diffraction grating, B...Substrate, 6...Feed screw, 9
...Slit unit. Agent Patent Attorney Kosuke Mai

Claims (1)

[Claims] The slit is slidable along a linear guide that can rotate with a fulcrum at one point on the Rowland circle, and the slit is oriented so that the normal to the slit surface erected at the center of the slit points toward the center of the diffraction grating. A spectroscopic device characterized by being installed at a certain angle.