JPH07260415A - Beam shield mechanism in laser interferometer for detecting stage position - Google Patents

Abstract

PURPOSE:To provide a beam shield mechanism in laser interferometer for detecting stage position in which the detection accuracy has no possibility of lowering due to the air flow. CONSTITUTION:A shield body 11 is fixed with an upper sealing member 14, a lower sealing member 15, and a pair of side sealing members 16 while surrounding a laser beam S on the four sides. A plane mirror 12 is covered, on the surface thereof, with a mirror protect 13. Each side sealing member 16 has triangular profile and the forward end part thereof is located in the proximity of the mirror protect 13. Furthermore, a guide rail 19 is provided with a cover part 19b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam shield mechanism used in a laser interferometer for detecting the position of a stage in a precision inspection and measurement instrument such as a laser microscope and capable of preventing the influence of air flow on laser light. It is a thing.

[0002]

2. Description of the Related Art Generally, in a precision inspection / measuring instrument such as a laser microscope, it is required that the stage for holding a sample has a sufficiently high positional accuracy. Therefore, it is necessary to accurately detect the current position of the stage. For example, in a certain type of laser microscope, the position of the stage is detected using a laser interferometer as shown below.

FIG. 4 is a diagram showing the configuration of the laser interferometer 1. This laser interferometer 1 has a stage 2 having two X and Y coordinates.
Each position in the direction is detected. The laser light S emitted from the laser head 3 is reflected by the turning mirror 4 and is perpendicular to each other by the beam splitter 5.
Each of the laser beams S is branched in the direction and enters the X read head 6a and the Y read head 6b. Then, X
The laser light S emitted from the read heads 6a and Y read heads 6b is shielded by beam shields 7a and 7b, respectively, and an X plane mirror 8a installed on the side of the stage 2 facing the read heads 6a and 6b, The Y plane mirror 8b is irradiated with the reflected light, and the reflected light is incident on the X read head 6a and the Y read head 6b again. Then, the respective read heads 6a and 6b measure the interference state, whereby the position of each of the X and Y coordinates of the stage 2 can be detected.

[0004]

By the way, FIG. 5 is a view showing the beam shield 7a (7b) and the plane mirror 8a (8b) on either side of the laser interferometer 1. As shown in FIG. As shown in this figure, the plane mirror 8a
Most of the circumference of the laser beam S incident on (8b) is covered by the beam shield 7a (7b), but the beam shield 7a near the plane mirror 8a (8b).
There is a gap between the frame 9 of (7b) and the plane mirror 8a (8b). Therefore, there is a problem in that the position detection accuracy of the laser interferometer 1 is reduced due to the fluctuation when the air A flows in this gap affecting the laser light S.

The present invention has been made to solve the above-mentioned problems, and a stage position detecting laser interferometer in which the position detecting accuracy is not deteriorated by the flow of air between the beam shield and the mirror. An object of the present invention is to provide a beam shield mechanism in.

[0006]

In order to achieve the above-mentioned object, a beam shield mechanism in a laser interferometer for detecting a stage position according to claim 1, wherein a shield main body which allows laser light to pass therethrough, and the shield main body. An upper seal member, a lower seal member, which is provided on the front end surface of the laser diode and surrounds the laser beam from four sides by being interposed between the front end surface and the mirror.
And a pair of side seal members.

Further, in the beam shield mechanism in the stage position detecting laser interferometer according to claim 2, a mirror protecting member having a window portion for passing the laser light is mounted on the surface of the mirror, and the pair of sides. Each of the partial seal members is formed so that its cross section has a triangular shape, and its bottom surface is attached to the tip end surface of the shield body.

The beam shield mechanism in the laser interferometer for detecting a stage position according to claim 3 extends horizontally above the upper seal member so as to cover the gap between the mirror and the upper seal member. A cover is provided.

[0009]

In the beam shield mechanism of the laser interferometer for detecting a stage position according to claim 1, the laser beam is emitted by the upper seal member, the lower seal member, and the pair of side seal members interposed between the shield body and the mirror. Since it is surrounded on all sides, the air flow from the periphery is blocked by these seal members, and the laser light is not affected by the air flow.

Further, in the beam shield mechanism in the laser interferometer for detecting a stage position according to the second aspect, the surface of the mirror is surely protected by mounting the mirror protection member, and each side seal member is Since it is attached to the shield body at the bottom of the member with a triangular cross section,
The tip edge portion faces the mirror protection member side. Therefore, even when the side seal member and the mirror protection member come into contact with each other as the stage horizontally moves, the contact area is minimized.

Further, according to the beam shield mechanism in the laser interferometer for detecting a stage position according to claim 3, since the cover is provided above the upper seal member so as to cover the gap between the mirror and the upper seal member, This cover reliably blocks the flow of air from above.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a beam shield mechanism in a stage position detecting laser interferometer of the present invention will be described below with reference to FIGS. The beam shield mechanism of this embodiment is applied to the laser interferometer 1 shown in FIG. 4, FIG. 1 is a front view showing the beam shield mechanism 10, and FIG. 3 and 4 are transverse sectional views. Further, reference numeral 11 in the drawing is a shield body,
12 is a plane mirror (mirror), 13 is a mirror protect (mirror protection member), 14 is an upper seal member, 15
Is a lower seal member, and 16 is a side seal member.

As shown in FIG. 2, a stage (not shown)
A mirror plate 17 is attached to the side of the mirror plate 17, and the plane mirror 12 is attached to the mirror plate 17 via support members 18, 18. The mirror protect 13 is attached so as to cover the surface of the plane mirror 12. The mirror protect 13 is, for example, a box body made of a plate material having a thickness of about 1 mm, and as shown in FIG. 1, the front plate portion 13 a has a horizontally long shape for transmitting the laser light S to the plane mirror 12. The window portion 13b is formed and fixed so that the inner surface side is in contact with the surface of the plane mirror 12. Further, as shown in FIG. 2, the rear side of the mirror protect 13 is opened, and the upper plate portion 13c extends rearward and is fixed to the upper surface of the mirror plate 17. Further, a guide rail 19 is fixed to the upper plate portion 13c of the mirror protect 13, and as shown in FIGS. 1 and 2, the guide rail 19 is provided with a guide portion 19a extending in the side direction of the stage. .

On the other hand, as shown in FIG. 2, a shield body 11 for shielding the laser light S is installed between the read head (not shown) and the plane mirror 12. The shield body 11 has a bellows-shaped shield tube 20 surrounding the laser beam S, a frame 21 having a circular window portion 21a for transmitting the laser beam S, and a frame 21 for fixing the frame 21 as shown in FIG. 2 and the guide roller 2 protruding toward the plane mirror 12 side below the mounting portion 22, as shown in FIG.
3 is provided. The guide roller 23 is adapted to engage with the guide portion 19a of the guide rail 19 so that the plane mirror 12 moves in the direction of arrow B, B in FIG. 1 with respect to the shield body 11. It has become.

A block-shaped upper seal member 14 and a lower seal member 15 are installed above and below the window portion 21a of the frame 21 of the shield body 11, respectively. As shown in FIG. 2, the surfaces of these seal members 14 and 15 facing the plain mirror 12 have a slight gap between them and the mirror protect 13. Further, as shown in FIG. 1, cutouts 14a, 14a, 15a, 1a, 1a are formed in the lower part of the upper seal member 14 and in the upper part of the lower seal member 15 on both sides of the window 21a.
5a is formed, and these notches 14a, 14a,
A pair of side seal members 16 and 16 are fixed to the frame 21 so as to be fitted to 15a and 15a. As shown in FIG. 3, each of the side seal members 16 is formed by using chloroprene rubber as a material and has a cross section formed in an isosceles triangle shape. The tip edges of the lower seal members 14 and 15 are closer to the surface of the mirror protect 13 than the tips thereof. Therefore, the laser light S between the shield body 11 and the plane mirror 12 is surrounded on all sides by these upper, lower and side seal members 14, 15, 16.

Further, as shown in FIG. 2, the tip end of the guide rail 19 is a cover portion 19b (cover) protruding forward from the front surface of the mirror protect 13. The cover portion 19b is located above the upper seal member 14 and covers the gap between the upper seal member 14 and the mirror protect 13 from above.

In the laser interferometer 1 equipped with the beam shield mechanism 10 having the above-mentioned structure, the laser beam S is applied to the upper seal member 1.
4, lower seal member 15, a pair of side seal members 16,
Since it is surrounded from four sides by 16, the air flow A from various directions in the gap between the shield body 11 and the plane mirror 12 can be blocked,
Since the laser beam S is not affected by the air flow A, the position of the stage can be detected without degrading the accuracy.

Further, since the surface of the plane mirror 12 is covered with the mirror protector 13, the air flow A in the immediate vicinity of the surface of the plane mirror 12 is blocked and the pair of side seal members 16, 16 are provided. Can be prevented from coming into direct contact with the surface of the plane mirror 12 even if is mounted sufficiently close to the plane mirror 12.

The pair of side seal members 16, 16
Since the cross section has an isosceles triangle shape and its tip edge is sufficiently close to the mirror protect 13, the air flow A from the side can be surely blocked and the stage is horizontal. Even if the side seal member 16 comes into contact with the mirror protect 13 during movement, the contact area is as small as possible, and the tip edge is slightly elastically deformed, so that the stage It is possible to eliminate the possibility of hindering smooth movement and causing a large amount of dust and scratches.

Further, regarding the upper and lower sealing members 14 and 15, if there is contact with the mirror protector 13 as described above, the resistance against horizontal movement of the stage increases, which is not preferable. Therefore, the upper and lower sealing members 14 and 15 and the mirror protector 13
Although there is a slight gap between and, since the gap is covered with the cover portion 19b of the guide rail 19 from above, the air flow A from above can be reliably blocked. For example, when a precision instrument such as a laser microscope using the laser interferometer 1 is used in a down-flow type clean room, etc., there is a constant air flow from the upper side to the lower side in the clean room. Providing such a cover portion 19b is very effective.

In this embodiment, the pair of side seal members 16 and 16 are prevented from contacting the mirror protector 13, but the pair of side seal members 16 and 16 slightly contact the mirror protector 13. You may do it. Even in this case, the surface of the plane mirror 12 should not be contacted. In addition, each seal member 14, 15, 1
The material and shape of 6 and the mirror protect 13 can be appropriately set.

[0022]

As described above in detail, the first aspect of the present invention is as follows.
In the beam shield mechanism in the stage position detection laser interferometer described above, an upper seal member, a lower seal member, and a pair of side seal members are provided between the shield body and the mirror so as to surround the laser beam from four sides. By doing so, the flow of air from the periphery can be blocked by these seal members, and the influence of the air flow does not affect the laser light.Therefore, according to the laser interferometer equipped with this beam shield mechanism, The position of the stage can be detected without lowering the accuracy.

Further, according to the beam shield mechanism in the laser interferometer for detecting the stage position according to the second aspect, since the mirror protection member is mounted on the surface of the mirror, the air flow in the immediate vicinity of the mirror surface is shut off. In addition to this, it is possible to prevent the seal member from directly contacting the mirror. In addition, each side seal member has its tip edge facing the mirror protection member side, and even if the side seal member and the mirror protection member come into contact with each other, the contact area is as small as possible, It is possible to prevent the smooth movement of the stage and eliminate the possibility of generating a large amount of dust and scratches.

Further, according to the beam shield mechanism in the laser interferometer for detecting a stage position according to claim 3, since the cover is provided above the upper seal member so as to cover the gap between the mirror and the upper seal member, With this cover, the flow of air from above can be blocked more reliably, and the position detection accuracy of the laser interferometer can be reliably prevented from lowering.

[Brief description of drawings]

FIG. 1 is a front view showing a beam shield mechanism in a laser interferometer which is an embodiment of the present invention.

FIG. 2 is an enlarged vertical cross-sectional view of a main part of the beam shield mechanism.

FIG. 3 is a cross-sectional view of the same.

FIG. 4 is a diagram showing a configuration of a laser interferometer.

FIG. 5 is a vertical cross-sectional view showing an enlarged main part of a conventional laser interferometer.

[Explanation of symbols]

 1 Laser Interferometer (Laser Interferometer for Stage Position Detection) 10 Beam Shield Mechanism 11 Shield Main Body 12 Plain Mirror (Mirror) 13 Mirror Protect (Mirror Protecting Member) 13b Window 14 Upper Sealing Member 15 Lower Sealing Member 16 Side Sealing Member 19b Cover (cover) S Laser light

Claims (3)

[Claims] 1. A laser interferometer for detecting the position of a stage by irradiating a mirror mounted on a side portion of a stage that moves in the horizontal direction with a laser beam and receiving the reflected light thereof. A beam shield mechanism for shielding laser light from the surroundings, comprising: a shield body that allows the laser light to pass therethrough; and a shield body that is provided on the tip surface of the shield body and that is interposed between the tip surface and the mirror. A beam shield mechanism in a stage position detecting laser interferometer, comprising an upper seal member surrounding the laser beam from four sides, a lower seal member, and a pair of side seal members. 2. The beam shield mechanism in the laser interferometer for detecting a stage position according to claim 1, wherein a mirror protection member having a window portion that allows the laser light to pass through is mounted on a surface of the mirror, In the laser interferometer for detecting a stage position, each of the side seal members is formed to have a triangular cross section, and a bottom surface of the side seal member is attached to a tip end surface of the shield body. Beam shield mechanism. 3. The beam shield mechanism in the laser interferometer for detecting a stage position according to claim 1, wherein a horizontal direction is provided above the upper seal member so as to cover a gap between the mirror and the upper seal member. A beam shield mechanism in a laser interferometer for detecting a stage position, which is provided with an extending cover.