JP2551002B2 - Lighting device having elliptical mirror - Google Patents

Description

The present invention relates to an illuminating device having an ellipsoidal mirror, and more particularly to an optical system for detecting the position of a light source thereof.

[Conventional technology]

As a conventional device of this kind, as disclosed in JP-A-57-85019 and JP-A-58-205127, the light emitting portion of the light source is located at the first focal point of the ellipsoidal mirror, and the second device is used. A configuration is known in which two sets of detection optical systems for the light source position are arranged after the focal position.

Further, as disclosed in JP-A-60-168002 as a light source position detecting device, a so-called pinhole camera is provided by inserting a pinhole between the first focus and the second focus of an ellipsoidal mirror. A configuration for observing a light source image formed on the second focal plane is also known in the same manner.

[Problems to be solved by the invention]

In the former configuration described above, since the optical axes of the two sets of light source position detection optical systems form a predetermined angle with respect to the optical axis of the illumination optical system main body, a light source image observed from two directions is formed. There is a drawback that the positions to be separated are separated. This drawback is a problem that workability is poor when adjusting the position of the light source with respect to the ellipsoidal mirror while observing the light source images by the two light source position detecting optical systems.

On the other hand, in the configuration using the pinhole like the latter described above, there is an advantage that a plurality of light source images observed from a plurality of directions are formed on the same plane, while the position where the light source images are formed is an ellipse. Since it is limited to the position of the second focal plane of the surface mirror, the restriction on the configuration of the entire apparatus becomes large. That is, in order to adjust the position of the light source while observing the light source image, there are restrictions on the arrangement. In order to reduce this restriction, it is necessary to make the first focus and the second focus of the ellipsoidal mirror as far apart as possible, that is, an ellipsoidal mirror having a large eccentricity. There is also a problem that the configuration of such an ellipsoidal mirror is not necessarily optimal from the viewpoint of the configuration.

Therefore, an object of the present invention is to provide an illuminating device that can observe light source images from a plurality of different directions at the same time and that does not impose structural restrictions on a main illumination optical system having an ellipsoidal mirror. is there.

[Means for solving problems]

The present invention relates to an illumination optical system having an ellipsoidal mirror and a light source arranged such that a main light emitting portion is located at a first focus position of the ellipsoidal mirror, and a light source position detection for detecting the position of the light source. In an illumination device having an optical system, the light source position detection optical system converts an chief ray passing through a second focal point of the ellipsoidal mirror so as to be substantially parallel to an optical axis of the illumination optical system, and the optical member. It has a condensing member for condensing the light flux emitted from the member, and an observation surface arranged at a condensing position by the condensing member.

[Action]

According to the configuration of the present invention as described above, a plurality of optical systems that form a light source image can be arranged so that their optical axes are parallel to each other after the second focus of the ellipsoidal mirror, which is different. It is possible to form the light source image from the direction on the same plane. Therefore, the light sources can be simultaneously observed on the same plane from two or more directions, and the observation system can be arranged after the second focal point of the ellipsoidal mirror, so that the structural restrictions on the entire illumination device are reduced. It is possible.

〔Example〕

 Hereinafter, the present invention will be described based on examples.

FIG. 1 is a perspective view showing a schematic configuration of an embodiment according to the present invention. This embodiment is applied to a reduction projection type exposure apparatus for manufacturing VLSI using an ellipsoidal mirror.

Ultra-high pressure mercury lamp 11 that arc the position of the light source is provided so as to substantially coincide with the first focus F ₁ of the ellipsoidal mirror 12, the light beam emanating from the first position of the focal point F ₁ and the second focus of the ellipsoidal mirror 12
It is focused on F ₂ , and a light source image is formed there. Elliptical mirror 12
And a dichroic mirror installed obliquely between the second focal point F ₂
The light beam reflected by 17 passes through an optical member 18 including an interference filter and an optical integrator, is reflected by a reflecting mirror 19, and then is guided to a condenser lens 20. The light flux emitted from the condenser lens 20 uniformly illuminates the mask 21, and the pattern image on the mask is reduced and projected on the wafer surface (not shown) by the reduction projection lens (not shown).

In contrast to such an illumination optical system, as a light source position detecting optical system, a positive lens 30 whose focal position is matched with a position of a second focal point F ₂ behind the dichroic mirror 17 is arranged, and two minute apertures are arranged behind it. Shading plates 31 and 2 having 31a and 31b
Two condenser lenses 32a and 32b arranged in parallel corresponding to one minute aperture are provided, and an image plane 33 is formed on the back focal plane of each condenser lens. That is, among the light fluxes emitted from the light source, the light flux that contributes to the formation of the light source image for detecting the light source position is limited by the minute aperture of the light shielding plate 31 as the aperture stop, but the partial regions S ₁ and S of the ellipsoidal mirror. After being reflected at ₂ ,
The light is focused on the second focal point F ₂ , converted into a parallel light flux by the positive lens 30, passes through the light blocking plate 31, and a pair of focusing lenses 32a and 32a.
The light is focused on the image plane 33 by b. Here, the optical axes A ₁ and A of the two condenser lenses 33a and 32b arranged in parallel are arranged.
_{When 2} is reversed from the image plane 33 side, the two intersect at the second focal point F ₂ of the ellipsoidal mirror 12 by the positive lens 30, are reflected by the ellipsoidal mirror, and then are orthogonal to each other on the light source 11. Each optical axis is also orthogonal to the optical axis A ₀ of the illumination optical system. And
Each of the optical axes A ₁ and A ₂ coincides with the chief ray of the image forming light flux of the light source image by each optical system.

FIG. 2 shows a light source position detecting optical system according to the present invention.
FIG. 9 is a developed optical path diagram of an optical system having a positive lens 32a as a condenser lens. The light rays in the figure show the conjugate relation for the minute aperture 31 on the light shielding plate as the aperture stop. This configuration is equivalent to the optical system having the other positive lens 32b. The light emitted from the first focus F ₁ of the ellipsoidal mirror 12 is focused on the second focus F _2, and an image of the light source is formed there. This image includes a positive lens 30, a light blocking plate 31 having a minute aperture 31a as an aperture stop, and a condenser lens 32 as an observation objective lens.
It is re-imaged on the focusing screen arranged on the image plane 33 through a. The focus position of the positive lens 30 is almost the first focus of the ellipsoidal mirror 12.
Since it is located on F ₁ , the chief ray emitted from the positive lens 30 is parallel to the optical axis A ₀ of the illumination optical system, and the image plane formed by the condenser lens 32a is relative to the optical axis A ₀ of the illumination optical system. It will be vertical.

Therefore, assuming orthogonal coordinates as shown in FIG. 1 for the configuration of the illuminating device and the optical axis direction of the illumination optical system is the Z axis,
The light source position detection optical system enables observation of the light source images in the X and Y directions orthogonal to each other at one location on the image plane 33 at the same time. And 3 to 4 as condenser lenses
It goes without saying that if the positive lenses are arranged in parallel, the position of the light source can be observed from 3 to 4 directions.

The positive lens 30 is the most desirable element as an optical member that converts the principal ray passing through the second focal point of the ellipsoidal mirror so as to be substantially parallel to the optical axis of the illumination optical system. As an optical member that is parallel to the optical axis A ₀ of
It is also possible to use a prism.

〔The invention's effect〕

As described above, according to the present invention, it is possible to simultaneously observe light source images from a plurality of different directions at one location, which improves the operability of centering work of the light source, and further, the illumination optical system having the ellipsoidal mirror. It is possible to realize an excellent lighting device that does not impose any restrictions on the configuration.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an embodiment according to the present invention,
FIG. 2 is a developed optical path diagram of an optical system for detecting a light source position. [Description of symbols of main parts] 11 ... Light source 12 ... Ellipsoidal mirror F ₁ ...... First focus of ellipsoidal mirror F ₂ ...... Second focus of ellipsoidal mirror 30 ...... Principal ray parallel to optical axis Optical member (positive lens) 32a, 32b …… Condensing lens 33 …… Image plane

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-57-85019 (JP, A) JP-A-60-2914 (JP, A) JP-A-61-148629 (JP, A)

Claims (3)

(57) [Claims] 1. An illumination optical system having an ellipsoidal mirror and a light source arranged such that a main light emitting portion is located at a first focal position of the ellipsoidal mirror, and a light source position for detecting the position of the light source. In an illumination device having a detection optical system, the light source position detection optical system converts an chief ray passing through a second focal point of the ellipsoidal mirror so as to be substantially parallel to an optical axis of the illumination optical system, It has a condensing member for condensing the light flux emitted from the optical member, and an observation surface arranged at a condensing position by the condensing member, and light source images from a plurality of different directions are formed on the observation surface. A lighting device characterized in that 2. The illumination device according to claim 1, wherein the optical member is a positive lens arranged so that a focal point substantially coincides with a second focal position of the ellipsoidal mirror. . 3. The light condensing member of the light source position detecting optical system has two positive lenses arranged in parallel with the optical axis of the illumination optical system interposed therebetween, and passes through the centers of the two positive lenses. The chief ray
The illumination device according to claim 2, wherein the illumination device is substantially orthogonal to the optical axis of the illumination optical system due to reflection on the ellipsoidal mirror.