JPH0495908A - Optical device for projection - Google Patents

Abstract

PURPOSE:To adjust alignment with high precision by comparing the cross-sectional form of light with a reference pattern, obtaining the positional deviation of a mirror and outputting an alignment command in accordance with the positional deviation to a posture adjusting mechanism. CONSTITUTION:A pattern recognition part 54 performs the recognition of pattern between the reference pattern for alignment stored in a reference pattern memory 52 and a pattern for alignment stored in an image memory 53 and obtains the error of alignment. Then, a master control part 51 transmits the position in a Z direction and the theta direction of a concave mirror 2 to a driving circuit 58 through an output part 57 as the alignment command S. Then, the position in the Z direction and the theta direction of a convex mirror 2 are adjusted, and the concave mirror 1 and the convex mirror 2 are aligned. Thus, the alignment is adjusted with high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to a projection optical device using, for example, a Schwarzschild type or Offner type optical system.

(Prior Art) FIG. 9 is a block diagram of a Schwarzschild type projection optical device. This projection optical device consists of a concave mirror 1 and a convex mirror 2.
The object point 3 is arranged on the back side of the convex mirror 2. In this case, the concave mirror 1 has a reflective mirror formed on the outer side of the circumference, and a light transmitting part formed in the center.

With this configuration, the light emitted from the object point 3 reaches the concave mirror 1 and is reflected toward the convex mirror 2, and is imaged by the convex mirror 2 at the image point 4.

Further, FIG. 10 is a configuration diagram of an off-chip type projection optical device. This projection optical device has a configuration in which a concave mirror 5 and a convex mirror 6 are arranged facing each other, and an object point 7 is arranged at a position where the concave mirror 5 is desired. With such a configuration, the light emitted from the object point 7 is reflected by the concave mirror 5, reaches the convex mirror 6, is reflected by the convex mirror 6, enters the concave mirror 5 again, and is reflected by the concave mirror 5. The light is focused and imaged at an image point 8.

As mentioned above, there are convex projection optical devices, but in any device, the concave mirrors 1 and 5 and the convex mirror 2.6 must be aligned with high precision. This alignment adjustment of each mirror is performed by interferometry. To explain with reference to the off-chip projection system shown in FIG. 11, for example, the He-Ne laser beam 10 is
The light is transmitted through the condensing mirror 5, condensed by the condensing lens 12, and irradiated onto the concave mirror 5. On the other hand, a concave mirror 13 is arranged at a position past the image point 8 to return the He-Ne laser beam 10 to the same optical path as the one through which it was transmitted. As a result, interference occurs on the reference mirror 11 between the incident He-Ne laser beam 10 and the He-Ne laser beam returned from the optical system. Therefore, by observing these interference fringes, for example, the position of the convex mirror 6 is finely adjusted, and the alignment between the concave mirror 5 and the convex mirror 6 is adjusted.

However, the alignment accuracy between the concave mirrors 1 and 5 and the convex mirror 26 is determined by the formation accuracy of these mirrors alone and the accuracy of their combination. It is extremely difficult to increase the accuracy of the combination since there is no established alignment adjustment algorithm. Further, even if alignment adjustment is performed by -degrees, the concave mirrors 1, 5 and the convex mirrors 2, 6 may become misaligned due to temperature changes, mechanical deformation, and the like.

(Problem to be solved by the invention) As described above, alignment adjustment was extremely difficult.

Therefore, an object of the present invention is to provide a projection optical device that can perform alignment adjustment with high precision.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a projection optical device that enlarges and images an arbitrary pattern using an optical system having a mirror, in which an alignment pattern is formed and projection light from the optical system is formed. a light branching means that forms at least a part into a light cross-sectional shape corresponding to the alignment pattern and branches the light; an attitude adjustment mechanism provided on the mirror that finely adjusts the attitude of the mirror; and a light cross-section of the branched light of the light branching means. This projection optical device attempts to achieve the above object by including an alignment adjustment means that compares the shape with a reference pattern to determine the positional deviation of the mirror, and issues an alignment command to the attitude adjustment mechanism according to this positional deviation.

(Function) By providing such a means, at least a part of the projected light from the optical system is shaped and branched by the light branching means into a light cross-sectional shape corresponding to the alignment pattern, and the light cross-section of this branched light is The alignment adjustment means compares the shape with the reference pattern to determine the positional deviation of the mirror, and the position is adjusted by sending an alignment command corresponding to this positional deviation to the attitude adjustment mechanism.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Note that the same parts as in FIG. 8 are given the same reference numerals, and detailed explanation thereof will be omitted.

FIG. 1 is a block diagram of a projection optical device applied to the Schwarzund type. The convex mirror 2 is provided in a fine adjustment mechanism 20. The fine adjustment mechanism 20 has a function of slightly moving the position of the convex mirror 2 in the optical axis Z direction and changing the direction of the surface of the convex mirror 2 in the θ direction. Specifically, the configuration is shown in FIG. 2, in which FIG. 2(a) is a front view and FIG. 2(b) is a side view. The bottom part 21 has a support frame 2
2 is provided. A concave spherical surface 23 is formed on the upper part of the support frame 22, and a spherical bearing 24 is provided in contact with this spherical surface 23 so as to be slidable in the θ direction. or,
The bottom part 21 is provided with adjusting screws 25, 26, 27 at each position forming a triangle. These adjusting screws 25.2
By adjusting 6.27, the spherical bearing 24 can slide in the θ direction. And these adjustment screws 2
Motors 28, 29, and 30 are connected to motors 5, 26, and 27, respectively. On the other hand, a crown-shaped elastic spring 31 is provided on the spherical bearing 24, and this crown-shaped elastic spring 31
A convex mirror 2 is placed supported by. Furthermore, a piezoelectric element 32 is provided on the spherical bearing 24. This piezoelectric element 32 is connected to the bottom surface of the convex mirror 2 to slightly move the position of the convex mirror 2 in the Z direction.

On the other hand, a branching mirror 40 is arranged on the optical system side of the image point 4. This branching mirror 40 branches a part of the projection light, and as shown in FIG.
．． 43 is formed, and areas other than these regions 42 and 43 are formed as a mirror 44. This branching mirror 40 rotates at a predetermined number of rotations in the direction of arrow (A).

A photodetector 45 made of a CCD (solid-state imaging device) is arranged in the branching direction of the branching mirror 40. This photodetector 45 receives the branched light and outputs an image signal of the alignment pattern formed on the branching mirror 40.

The adjustment processing device 50 has a function of comparing the alignment pattern formed on the branched light with a reference pattern, determining the relative positional deviation between the concave mirror 1 and the convex mirror 2, and issuing an alignment command according to this positional deviation. It is something that you have. Specifically, the main control section 51 is provided with a reference pattern memory 52 and an image memory 53.
is connected, and the pattern recognition section 54 and alignment adjustment section 55 operate in response to commands from the main control section 51. Further, an input section 56 and an output section 57 are provided. The reference pattern memory 52 stores reference image data of the alignment pattern. The image signal from the photodetector 45 is converted into a digital image signal by an input section 56 and stored in an image memory 53 as image data. Pattern recognition section 54
The method performs pattern recognition between the alignment pattern of the reference image data and the alignment pattern stored in the image memory 53 to determine the alignment error.
The alignment adjustment unit 54 has a function of simulating and determining the Z-direction position and θ-direction of the concave mirror 2 in order to match the alignment pattern detected by the photodetector 45 with the reference alignment pattern based on the alignment error. have. However, the main control unit 51
is configured to send the Z-direction position and θ-direction of the concave mirror 2 to the drive circuit 58 through the output section 57 as an alignment command S.

This drive circuit 58 has a function of receiving the alignment command S, determining the drive amount of the piezoelectric element 32 and each motor 28, 29, 30, and driving these motors 28, 29, 30.

Next, the operation of the apparatus configured as described above will be explained.

The light emitted from the object point 3 reaches the concave mirror 1, is reflected toward the convex mirror 2, is condensed by the convex mirror 2, and is imaged at the image point 4.

In this state, the branching mirror 40 rotates, and the projection light passes through the light transmission areas 42 and 43 of the branching mirror 40, and part of it is branched by the reflecting mirror 44 in the direction in which the photodetector 45 is arranged. The photodetector 45 receives the branched light and outputs an image signal corresponding to the alignment pattern. This image signal is converted into a digital image signal by the input section 56 of the adjustment processing device 50 and stored as image data in the image memory 53.
issues a movement command. The pattern recognition unit 54 performs pattern recognition between the reference alignment pattern stored in the reference pattern memory 52 and the alignment pattern stored in the image memory 53 to obtain an alignment error. Next, the alignment adjustment unit 54 performs simulation to determine the Z-direction position and θ-direction of the concave mirror 2 in order to match the alignment pattern detected by the photodetector 45 with the reference alignment pattern based on the alignment error. . Then, the main control section 51 sends the two-direction position and θ direction of the concave mirror 2 as an alignment command S to the drive circuit 58 through the output section 57.

The drive circuit 58 receives the alignment command S, determines the drive amount of the piezoelectric element 32 and each motor 28, 29, and 30, and drives the piezoelectric element 32 and the motors 28, 29, and 30. In this way, the position of the convex mirror 2 is adjusted in the Z direction and the θ direction, and the concave mirror 1 and the convex mirror 2 are aligned.

In this way, in the above embodiment, at least a part of the projection light from the optical system is shaped into a light cross-sectional shape corresponding to the alignment pattern by the branching mirror 40 and branched,
The optical cross-sectional shape of this branched light is compared with the reference pattern to determine the positional shift of the convex mirror 2 and adjust the attitude of the convex mirror 2, so the alignment between the concave mirror 1 and the convex mirror 2 is automatically performed. can be done. In this case, since pattern recognition of the alignment pattern is performed, alignment can be performed with high precision. In addition, a photodetector 45 consisting of a CCD
, it is possible to receive light in a wide range of wavelengths from the visible light region to the soft X-ray region. Moreover, since the branching mirror 40 branches a part of the projection light, an arbitrary pattern can be imaged at the image point 4 at the same time as alignment.

It should be noted that the present invention is not limited to the one embodiment described above, and may be modified without departing from the spirit thereof. For example, the fine adjustment mechanism 20 may include a fine movement mechanism in the Z direction and a mechanism for changing the direction in the θ direction, or only one of these mechanisms may be used depending on the adjustment content required for the convex mirror 2. Figure 4 is a configuration diagram of the fine adjustment mechanism in two directions.
Figure a) is a front view, and figure (b) is a side view. FIG. 5 is a block diagram of the fine movement mechanism in the θ direction, with FIG. 5(a) being a front view and FIG. 5(b) being a side view. , in these figures, the same parts as in FIG. 2 are given the same reference numerals. A support frame 60 for supporting the convex mirror 2 is provided in the fine movement mechanism in the θ direction.

Next, a case where the present invention is applied to an off-chip projection optical device will be described with reference to the configuration diagram of FIG. 6. Note that the same parts as in FIG. 10 are given the same reference numerals, and detailed explanation thereof will be omitted. In this case, as shown in FIG. 7, the branching mirror 70 has light transmission holes 72 to 75 formed along the circumferential direction of a mirror body 71, and other parts of these holes 72 to 75 are formed in a reflection mirror 76. It is something. The image signal output from the photodetector 45 is sent to an adjustment processing device having the same configuration as the adjustment processing device 50 shown in FIG. This adjustment processing device has the same alignment pattern except that it has a circular pattern.

However, alignment commands for the Z-direction position and θ-direction of the concave mirror 6 are sent to the fine adjustment mechanism 20, and the concave mirror 5 and convex mirror 6 are aligned.

Further, the present invention utilizes synchrotron radiation light (SOR) emitted from a synchrotron radiation light source 80 as shown in FIG.
81 is reflected by the reflecting mirror 82 and projected onto the projection surface 83, a part of the projection light may be split by a beam splitter mirror 84 on which an alignment pattern is formed and sent to the photodetector 45. In this case, the photodetector 4
The image signal output from 5 is sent to an adjustment processing device having the same configuration as the adjustment processing device 50 shown in FIG. It will be sent to the adjustment mechanism.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a projection optical device that can perform alignment adjustment with high precision.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining an embodiment in which a projection optical device according to the present invention is applied to a Schharzschild type projection system, in which FIG. 1 is a configuration diagram, and FIG. The figure is
FIG. 3 is a configuration diagram of the flt adjustment mechanism, FIG. 3 is a configuration diagram of the branching mirror, FIGS. 4 and 5 are diagrams showing other configurations of the fine adjustment mechanism,
6 and 7 are diagrams for explaining the case where the projection optical device according to the present invention is applied to an off-na type projection system, in which FIG. 6 is a configuration diagram and FIG. 7 is a configuration of a branching mirror. 8 is a block diagram showing the case where it is applied to the projection of synchrotron radiation light, FIG. 9 is a block diagram of a Schharzschild type projection optical device, and FIG. 10 is a block diagram of an off-chie type projection optical device. , FIG. 11 is a diagram for explaining the prior art. 1... Concave mirror 2... Convex mirror 3... Object point, 4... Image point, 0... Fine adjustment mechanism, 0... Branching point 5... Photodetector, 0... ...Adjustment processing device, 8...Drive circuit.

Claims (1)

[Claims] In a projection optical device that magnifies and images an arbitrary pattern using an optical system having a mirror, an alignment pattern is formed and at least a part of the projection light from the optical system is shaped into a light cross-sectional shape corresponding to the alignment pattern. an attitude adjustment mechanism provided on the mirror to finely adjust the attitude of the mirror; and a position adjustment mechanism for determining the positional deviation of the mirror by comparing the optical cross-sectional shape of the branched light of the light branching means with a reference pattern. 1. A projection optical device comprising: alignment adjustment means for determining the positional deviation and issuing an alignment command to the attitude adjustment mechanism according to the positional deviation.