JPH06214142A - Lens holder - Google Patents

Abstract

PURPOSE:To provide a holder for surely holding a semicircular lens whose outer circumference is partly formed into a circular arc shape without affecting the plane accuracy of a lens. CONSTITUTION:Planes 1a and 1b parallel to each other are formed in a lens thickness direction on the circular arcuate outer circumferential part of the semicircular lens 1. Three connections 2a are installed on the positions of a lens frame 2 corresponding to the center part and both end parts of the circular arc on the outer circumferential part of the semicircular lens 1. Pressing metal fitting 3 is installed on the position corresponding to the connection 2a. The pressing metal fitting 3 is provided with an elastic pressing plate 4 formed to the shape of a triangle whose three apexes are cut off, two-point supporting plate 6 installed on the lens frame 2 and a pivot fixture 5 coming into contact with the plane 1a of the semicircular lens 1, and the pressing metal fitting is fixed on the lens frame 2 by a bolt 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens holder, and more particularly to a semicircular lens holder included in the construction of an optical system used in a projection exposure system of a scan exposure system.

[0002]

2. Description of the Related Art Conventionally generally used lenses have a circular outer periphery. Therefore, as shown in the sectional view of FIG. 5, the lens is loaded into the lens frame 13 having an annular seat having a diameter corresponding to the outer diameter of the lens 12,
The lens 12 is held by, for example, screwing the pressing ring 14 into the lens frame 13.

[0003]

However, depending on the specifications of the optical system of the exposure apparatus, when the optical path of the incident light IL and the optical path of the reflected light RL reflected by the reflecting mirror 10 are close to each other as shown in FIG. 6, for example. Will occur. In this case, assuming that the lens 11 is a lens required only for the optical path of the incident light, the conventional circular lens will adversely affect the optical path of the reflected light. Therefore, in this case, a semi-circular lens as shown in FIG. 3, that is, a lens in which only a part of the outer periphery is formed in an arc shape is used, and the optical path of the reflected light RL in FIG. 6 interferes with the lens 6. It is possible not to do so.

By the way, the semicircular lens shown in FIG. 3 cannot adopt the same holding method as the conventional lens as shown in FIG. This is because the semicircular lens does not have a circumference on all side surfaces thereof, and therefore, when the pressing ring 14 is screwed in, the lens is decentered in the center direction of the circumference shown by the broken line. Further, the cut portion of the semi-circular lens is for the light flux to pass therethrough, and there is also a problem that a holder or the like cannot be provided other than the outer peripheral portion formed in an arc shape.

Further, in the optical system of the exposure apparatus which requires high precision, high positional stability and lens surface precision are required for each of the lenses constituting the optical system. Contrary problems, such as the need to hold the lens strongly in order to increase the position stability, and the need to hold the lens with a holding force that does not stress the lens surface in order to improve the lens surface accuracy was there.

In view of the above problems, it is an object of the present invention to provide a lens holder for surely applying a semicircular lens only with its arcuate outer peripheral portion and not giving unnecessary stress to the lens. And

[0007]

In order to solve the above-mentioned problems, according to the present invention, a lens holder for holding a semicircular lens (1) in which only a part of the outer peripheral portion is formed in an arc shape is formed in an arc shape. The outer peripheral portion of the formed semicircular lens has surfaces (1a, 1b) parallel to each other in the thickness direction of the lens, and is arranged at positions corresponding to both end portions and the central portion of the outer peripheral portion and parallel to each other. A support member (2a) in surface contact with one of the surfaces (1b);
A lens pressing member (5) having a flat surface in surface contact with the other of the parallel surfaces (1a) and arranged at a position corresponding to the supporting member (2a); 5) and an elastic member (4) for pressing.

[0008]

According to the present invention, the semicircular lens outer peripheral portion is formed with arc-shaped portions on surfaces that are parallel to each other in the thickness direction of the lens, and the parallel surfaces are sandwiched from both sides. Moreover, since the elastic member is used for holding, the lens can be held securely without applying unnecessary stress to the surface of the lens. At this time, since the lens is held by the plane portion of the pivot fitting, the contact area with the lens is always constant, and the force for tightening the lens is dispersed.

Further, since the lens is held only by the arc-shaped outer periphery of the lens, these holders do not interfere with the optical paths of other light beams.

[0010]

1A and 1B are views showing the construction of a lens holder according to an embodiment of the present invention, wherein FIG. 1A is a plan view and FIG. 1B is a side view. The lens 1 is held by an annular lens frame 2 that supports the peripheral portion thereof, and a pressing metal member 3 that similarly biases the peripheral portion against the lens frame 2. The lens 1 has surfaces 1a and 1b parallel to each other in the thickness direction of the lens so that the lens 1 can be sandwiched in parallel between the pressing fitting 3 and the lens frame 2. The lens frame 2 has three seats 2a for supporting the peripheral portion of the lens having the parallel surfaces 1a and 1b. These three seats 2a are arranged at substantially equal intervals at positions corresponding to the arc-shaped outer circumference of the lens, as shown in the figure, in order to equally divide the bending due to its own weight when installed horizontally. The press fitting 3 is arranged at a position corresponding to the three seats 2a, and sandwiches and supports the parallel surfaces 1a and 1b together with the seats 2a. Further, although the same holding metal fitting 3 is used at all three locations, the holding metal fitting 3 is independent, unlike the holder for a normal circular lens, and can be used regardless of the size of the lens.

FIG. 2 is a detailed view showing a structure of a press fitting and a seat for sandwiching the lens. (A) is a plan view and (b) is a side view. The holding metal 3 is a holding plate 4,
It is composed of a pivot fitting 5, a two-point receiving plate 6, bolts 7 and the like. The pressing plate 4 has a hexagonal shape having long sides and short sides alternately, and its center is attached to the lens frame 2 by a bolt 7. Presser plate 4 and lens frame 2
A two-point receiving plate 6 is provided between and, and supports two sides of the three short side portions c, d, and e of the pressing plate 4. The remaining short side portion c is supported by the pivot fitting 5 arranged between the lens 1 and the other short side portion c. These three short sides c,
Since d and e have the same length and are at geometrical positions of equal division, they respectively receive 1/3 of the axial force of the bolt 7. The pressing plate 4 is an elastic member, and the elastic force biases the lens 1 against the seat 2a.

Generally, tightening the lens directly with bolts causes stress concentration, which may cause the lens to break. In the present invention, since the shape of the pressing plate is as described above, the force applied to the lens can be reduced to 1/3 that in the case of directly tightening with the bolt. In addition, the pivot metal fitting 5
Has a flat surface that contacts the parallel surface 1a of the lens 1 and a convex cylindrical surface that contacts the short side portion c, and the short side portion c of the pressing plate 4 with respect to the pivot fitting. It makes a line contact and can rotate within the range of the cylindrical surface. By using the pressing plate 4 This is a pivot bracket 5 and the elastic member, parallel surfaces 1a formed in the peripheral portion of the lens, 1b undulation in the circumferential direction and the radial direction of the lens, as shown in FIG. 4 theta _a , Θ _b , the pivot metal fitting 5 and the parallel surfaces 1a and 1b can be reliably brought into contact with each other. Further, the two-point receiving plate 6 has two short sides d, e.
The seat is machined so that only the one touches. The pressing plate 4 is supported so as not to move on the lens frame 2 together with the two-point receiving plate 6.

In this embodiment, the case where the lens held by the holder is a semicircular lens has been described, but the present invention is not limited to this, and there is no problem even if it is used when holding a conventional circular lens. Absent.

[0014]

As described above, according to the present invention, it is possible to obtain a holder which can surely hold a lens without deteriorating the surface accuracy of the semicircular lens.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a lens holder according to an embodiment of the present invention.

FIG. 2 is a detailed view showing a configuration of a press fitting for sandwiching a lens and a seat.

FIG. 3 is a diagram showing an example of a semicircular lens.

FIG. 4 is a diagram showing the waviness of the surface of the peripheral portion of the lens used in the example of the present invention

FIG. 5 is a diagram showing a configuration of a lens holder according to a conventional technique.

FIG. 6 is a diagram showing an example in which a semicircular lens is used in the optical system of the exposure apparatus.

[Explanation of symbols]

 1 semi-circular lens 1a, 1b parallel surfaces 2 lens frame 2a seat 3 retainer fitting 4 retainer plate 5 pivot fitting

Claims (1)

[Claims] 1. A lens holder for holding a semi-circular lens in which only a part of the outer peripheral portion is formed in an arc shape, wherein the outer peripheral portion of the semi-circular lens formed in the arc shape is
Support members that have surfaces parallel to each other in the thickness direction of the lens, are disposed at positions corresponding to both ends and the center of the outer peripheral portion, and are in surface contact with one of the parallel surfaces; A lens pressing member disposed in a position corresponding to the supporting member, the elastic member pressing the lens pressing member against the supporting member. Lens holder to be used.