KR101924540B1 - Alignment Method for Off-axis Reflective Optical System - Google Patents

Abstract

The present invention relates to a primary and secondary alignment system and method for non-axis reflective optical systems for achieving maximum optical performance of a non-axis reflective optical system and systematically aligning a mirror, comprising a parallel light source (interferometer light source, Distance object light source); A plane mirror aligned with an optical axis of the parallel light source; A main mirror for receiving and reflecting the parallel light source; A reference surface formed on the edge side of the main mirror and machined perpendicular to the z axis; A sub-diameter receiving the light incident from the main mirror aligned by the reference plane; And an imaging element (included in an interferometer) for imaging the interference fringe by receiving the light reflected from the sub-mirror. The main mirror of the non-axial reflecting optical system for achieving the optical performance of the non- It is possible to minimize the amount of light and minimize the distortion of the point spread function (PSF).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primary and secondary alignment system and method for a non-axis reflection optical system, and more particularly, to a primary and secondary alignment system and method for maximizing optical performance of a non-axis reflection optical system.

The overall optical performance of the reflective optical system is determined by the precision of the principal and minor diameters, and whether or not it is precisely collimated. This is common to not only the symmetric type optical system of the Cassegrain type but also the off-axis system. In the case of a symmetrical optical system, alignment of the optical axis is comparatively easy. However, in the case of the non-axis optical system, precise alignment as well as machining is very difficult and time-consuming due to an increase in alignment freedom due to the asymmetric structure. For this reason, it is generally very difficult to realize a non-axial optical system as an actual optical system.

However, unlike the symmetrical Cassegrain type optical system, the non-axial reflection optical system has no central obscuration, so that it is possible to minimize the amount of light caused by the shielding and distort the point spread function (PSF) It has many advantages. In addition, in recent years, it has become possible to extremely precisely and extremely precisely process the non-shrinking reflective optical surface, thereby improving the processing accuracy.

In general, a micrometer with a knob is provided on a stage on which optical components are to be installed in order to precisely align the non-reflecting optical system, and a micrometer such as a servo motor And a micrometer controlled by a driving unit is provided. However, in order to precisely align the position of the optical component using the conventional micrometer, a large space is required. Particularly, in the case of an infrared optical system, thermal noise may occur. Therefore, There is a problem that the cost increases and the risk increases during the operation.

To overcome this disadvantage, it is possible to design as afocal system to precisely align the stockpin and the minor diameter in the optical design stage. This is a unified strategy that takes into consideration the assembly and alignment of the optical system already in the optical design stage. Specifically, a reference surface is super-precisely processed in the optical surface machining step of the non-focus main mirror so that the non-focus system non-axial shear optical system can be precisely aligned using an interferometer, and this is used as a reference surface for alignment with the interferometer. In this way, the number of alignment degrees of freedom generated in the non-condensing optical system can be reduced, and precise and quick alignment can be achieved by compensation of the minor diameter.

Korean Patent Registration No. 10-0412174 (entitled: Reflective Reflection Optical System and Exposure Apparatus)

Therefore, an object of the present invention to solve the problems of the prior art is to maximize optical performance by precisely aligning the principal and minor diameters of the non-axis reflection optical system, thereby minimizing the light amount degradation and the distortion of the jumping function, which are advantages of the non- To provide a non-axis reflective optical system main and sub-alignment system and method.

In order to accomplish the above object, there is provided a non-axis reflective optical system main and sub-alignment system, comprising: a parallel light source that emits light traveling in a straight line and receives light reflected from the sub-mirror to form an interference fringe;

A plane mirror for receiving the parallel light source at a right angle to adjust the tilting of the parallel light source and controlling the parallel light source to reflect at a right angle;

A main mirror for receiving and reflecting the parallel light source;

A reference surface formed on the edge side of the main mirror and super-precision machined perpendicularly to the z axis; And

A sub-diameter receiving the light incident from the main mirror aligned by the reference plane;

.

The reference plane may be configured such that when the parallel light source is incident in the z-axis direction and is reflected in the z-axis direction, the main mirror is recognized as aligned.

The sub-

Aligning the optical axis of the sub-lens while compensating for the tilt, and returning to the plane-minor-main-scanning-interferometer after being reflected through the sub-mirror to reduce the interference pattern formed on the parallel light source (included in the interferometer) .

The parallel light source may be configured to image the light reflected through the sub-mirror and the main mirror, analyze the formed interference fringe by a computer, and recognize that the sub-mirror is aligned when the interference fringe is formed at the center.

According to an aspect of the present invention, there is provided a main reflecting mirror and a sub-mirror aligning method including a parallel light source (interferometer light source, infinite distance object light source) for emitting a linearly traveling light, a plane mirror aligned with an optical axis of the parallel light source, A main mirror for receiving and reflecting the parallel light source, and a reference surface formed on the edge side of the main mirror and machined at a right angle to the z axis, the method comprising the steps of: Adjusting a parallel light source such that light is incident perpendicularly to the plane of the plane; Adjusting the main mirror so that the parallel light sources simultaneously return horizontally with respect to the optical axis (z axis) by the reference surface formed at the edge of the main mirror; Entering a parallel light source adjusted to be incident on the main axis in parallel with the optical axis by a plane mirror; Entering at the main diameter; And aligning the optical axes of the main and sub-lenses while compensating the tilt of the sub-lens.

 Processing the collimated light source such that the collimated light source enters the reference surface and enters the z-axis direction and is reflected in the z-axis direction prior to the step of adjusting the collimated light source.

The step of aligning the optical axis of the sub-diameter may be configured to adjust the tilting of the sub-diameter while reducing the interference fringes reflected on the sub-diameter through the planar mirror, the sub-mirror, and the main mirror.

The step of aligning the optical axis of the subpixel may be configured to analyze the interference pattern of the parallel light source in which the light reflected through the subpixel is imaged by a computer and adjust the tilting of the subpixel so that interference fringes are well formed in the center of the imaging unit have.

Therefore, the system and method for aligning main and minor diameters of the non-shrinking optical system of the present invention has the effect of minimizing the distortion of the light quantity drop and the jumping function by maximizing the optical performance by aligning the principal and minor diameters of the non- .

In addition, the system and method for primary and minor alignment of the non-axis reflective optical system of the present invention can be used to precisely, quickly, and conveniently align main and minor diameters in a non-condensing optical system, .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an alignment device using a main mirror (including reference plane), a minor diameter, a plane mirror, and an interferometer according to an embodiment of the present invention. FIG.
2 is a view of an interference fringe imaged on a collimator while tilting a sphere according to an embodiment of the present invention.
3 is a flowchart illustrating a process of aligning principal and minor diameters of a non-shrinkage reflection optical system according to an exemplary embodiment of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings showing embodiments of the present invention.

FIG. 1 is a configuration diagram showing a configuration of an alignment device using a main mirror (including a reference plane), a minor diameter, a plane mirror, and an interferometer according to an embodiment of the present invention.

Referring to FIG. 1, the non-axial reflection optical system 100 of the present invention includes a parallel light source 110, a plane mirror 120, a main mirror 130, and a sub-mirror 140. The main mirror 130 is configured to include a reference surface 132 perpendicular to the z-axis.

The parallel light source 110 is a light source that emits light traveling in parallel in a straight line. The light emitted from the parallel light source 110 can be considered as a plane wave.

The tilting of the parallel light source 110 is adjusted so as to be incident on the plane mirror 120 at a right angle.

The parallel light source 110 adjusted to be incident at right angles to the plane mirror 120 is made incident on the main mirror 130.

At this time, a reference surface 132 formed at a right angle to the z axis is formed on the edge side of the main mirror 130. At this time, the reference plane 132 is super-precisely processed (diamond processed) so that the parallel light source 110 is incident and reflected in the z-axis direction. That is, the reference plane 132 is processed perpendicular to the z-axis to adjust the tilting of the main mirror 130 to align with the optical axis. When the light emitted in parallel from the parallel light source 110 is returned in parallel by the reference surface 132 formed at the edge of the main mirror 130, it can be determined that the tilting of the main mirror 130 is properly set. That is, when returning to coincide with the z-axis, it can be determined that the tilting of the main mirror 130 is properly set.

The aligned main mirror 130 causes the parallel light incident from the plane mirror 120 to enter the sub-mirror 140 side.

The sub-lens 140 aligns the optical axis of the sub-lens while compensating for the tilt. That is, the tilting of the sub-mirror 140 is controlled while reducing interference fringes formed through the parallel light source-plane-mirror-sub-mirror-main-mirror-parallel light source. That is, when the optimized pattern is generated while looking at the interference fringe of the parallel light source 110 in which the interference fringes are formed, it is determined that the tilting of the sub-mirror 140 is controlled inevitably.

2 is a view showing an interference fringe formed on a parallel light source while tilting a sphere according to an embodiment of the present invention.

Referring to FIG. 2, there is shown an interference fringe which is incident on the sub-mirror 140, reflected by the plane mirror 120, and then imaged onto the parallel light source 110 through the sub-mirror 140 and the main mirror 130. Accordingly, the tilting of the sub-mirror 140 is adjusted to detect the optimal position and the optimal interference pattern, thereby controlling the tilting of the sub-mirror 140.

That is, the parallel light source 110 serves as a light source, but is a region where light reflected through the sub-mirror 140 is imaged. The parallel light source 110 is contained within the interferometer and can be perceived by a computer to be at a point where the interference fringe is minimized at the center of the sphere.

FIG. 3 is a flowchart illustrating a process of aligning principal and minor diameters of a non-shrinkage reflective optical system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the reference plane 132 is processed perpendicular to the z-axis on the edge side of the main mirror 130, as described above in step S202. The reference plane 132 is super-precisely processed perpendicular to the z-axis to adjust the tilting of the main mirror 130 to match. When the parallel light source is incident and reflected in the z-axis direction, it can be seen that the main mirror 130 is aligned. On the other hand, the step of machining the reference surface 132 is prior to the aligning step.

In step S204, the parallel light source 110 is adjusted so that the light emitted from the parallel light source 110 is incident perpendicularly to the plane mirror 120.

In step S206, the parallel light source 110, which is adjusted to be incident at a right angle by the plane mirror 120, is incident on the main mirror 130.

The tilting of the main mirror 130 is adjusted so that the light emitted in parallel from the parallel light source 110 is horizontally returned to the z axis by the reference surface 132 formed at the edge of the main mirror 130 in step S208. At this time, when the reference plane 132 is incident perpendicularly to the z-axis, it can be determined that the tilting of the main mirror 130 is appropriately set.

In step S210, the main mirror 130 causes the parallel light incident from the parallel light source 110 to enter the sub-mirror 140.

In step S212, the sub-lens 140 aligns the optical axes of the main and sub-lenses while compensating for the tilt. That is, the tilting of the sub-mirror 140 is controlled while reducing the interference fringe formed on the parallel light source 110 through the planar mirror 120, the minor lens 140, and the main mirror 130. That is, when the optimized pattern is generated while looking at the interference fringe of the parallel light source 110 in which the interference fringes are formed, it is determined that the tilting of the sub-mirror 140 is controlled inevitably.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. will be. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

110: interferometer (balanced light source, imaging unit) 120:
130: main mirror 132: reference plane
140:

Claims (8)

A parallel light source that emits light traveling in a straight line and receives light reflected from a sub-mirror to form an interference fringe;
A plane mirror for receiving the parallel light source at a right angle to adjust the tilting of the parallel light source and controlling the parallel light source to reflect at a right angle;
A main mirror for receiving and reflecting the parallel light source;
A reference surface formed on the edge side of the main mirror and super-precision machined perpendicularly to the z axis; And
A sub-diameter receiving the light incident from the main mirror aligned by the reference plane;
/ RTI >
Wherein the reference plane is recognized as the main mirror is aligned when the parallel light source is incident and is incident in the z-axis direction and is reflected in the z-axis direction. delete The method according to claim 1,
Wherein the optical system is configured to align the optical axis of the sub-scan while compensating for the tilt, and to adjust the tilting of the sub-scan while reducing interference fringes reflected through the sub-scan and imaged on the parallel light source. The apparatus according to claim 1, wherein the parallel light source forms an image of the light reflected through the sub-mirror and the main mirror, analyzes the formed interference fringe by a computer, and when the interference fringe is formed at the center, The primary and minor alignment systems. A parallel light source that emits light traveling in a straight line, a plane mirror that receives the parallel light source at a right angle to adjust the tilting of the parallel light source and controls the parallel light source to reflect at a right angle, And a reference surface machined at right angles to the z-axis, which is formed on the outer edge side of the main mirror,
Processing the collimated light source such that the collimated light is incident on the reference surface and incident in a z-axis direction and reflected in a z-axis direction so that the main mirror is aligned;
Adjusting a parallel light source to cause the light emitted from the parallel light source to be incident perpendicularly to a plane mirror;
Entering the parallel light source adjusted to be incident at a right angle by the plane mirror into the main mirror;
Adjusting the main mirror so that light emitted from the parallel light source is returned horizontally with respect to the z axis by the reference surface formed at the edge of the main mirror;
The principal plane of the parallel light entering from the parallel light source into the sub-mirror; And
And aligning the optical axis of the main mirror with the optical axis of the submirror while compensating the tilt of the submirror. delete 6. The method of claim 5, wherein aligning the optical axis of the sub-
Aligning the optical axis of the sub-lens while compensating for tilt, and adjusting the tilting of the sub-mirror while reducing interference fringes reflected through the sub-mirror to form an image on the parallel light source. 6. The method of claim 5, wherein aligning the optical axis of the sub-
A computer analyzes the interference pattern of the parallel light source in which light reflected through the sub-image is formed, and adjusts the tilting of the sub-mirror so that the interference fringe is well formed at the center of the image forming portion.

Images