WAVEFRONT ABERRATION MEASURING METHOD AND DEVICE THEREFOR

• US 20120019813A1
• Filed: 01/22/2010
• Published: 01/26/2012
• Est. Priority Date: 02/13/2009
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yoshitake, Yasuhiro, Yoshida, Minoru, Oka, Keiko
• Granted Patent: US 8,705,024 B2
• Time in Patent Office: Days
• US Class Current: 356/213
• CPC Class Codes: G01M 11/0207 Details of measuring devices
• CPC Class Codes: G01M 11/0257 by analyzing the image formed by the object to be tested

Abstract

Measurement cannot be made when trying to measure a wavefront aberration of a wide-angle lens, being wide in a field of view, comparing to a focus distance, by a Shack-Hartmann sensor, since an inclination of the wavefront exceeds an allowable value of inclination of the Shack-Hartmann sensor.

The Shack-Hartmann sensor is inclined at a position of a pupil of a lens, and is controlled so that it lies within the allowable value mentioned above. Photographing is made through step & repeat while overlapping at the same position, to compose in such a manner that overlapping spots are piled up, and thereby measuring the wavefront aberration of the lens having a large pupil diameter.

Claims

1. A wavefront aberration measuring device, comprising:

a first table means being movable on a plane surface;

a point light source forming means for forming a point light source, being mounted on said first table means;

a second table means for mounting a measuring object thereon, being able to rotate;

a Shack-Hartmann sensor for detecting a light emitting from the point light source, which is formed by said point light source forming means, and transmitting through a lens to be inspected, which is mounted on said second table means; and

a signal processing means for processing an output signal from said Shack-Hartmann sensor detecting the light, and thereby obtaining wavefront aberration of said lens to be inspected, and further comprising

an adjustment means, wherein said adjustment means adjusts an inclination and a position of said Shack-Hartmann sensor or an optical path of the light transmitting through said lens to be inspected, so that the light emitting from the point light source of said point light source forming means and transmitting through the lens to be inspected, which is mounted on said second table means, is detected by said Shack-Hartmann sensor upon a pupil surface of said lens to be inspected or a surface conjugate with said pupil surface, depending on a position of said point light source.

2. The wavefront aberration measuring device, as described in the claim 1, wherein said adjustment means comprises a gonio-stage for adjusting an inclination angle of said Shack-Hartmann sensor and a table movable within a plane surface for adjusting the position of said Shack-Hartmann sensor on the pupil surface of said lens to be inspected.

3. The wavefront aberration measuring device, as described in the claim 1, wherein said adjustment means has a rotatable mirror for adjusting the optical path of said transmitting light on the pupil surface of said lens to be inspected, so that the light emitting from said point light source and transmitting through the lens to be inspected, which is mounted on said second table means, can propagate along an optical axis of said lens to be inspected, and a relay lens for transmitting the light, the optical path of which is adjusted on by said rotatable mirror and for forming a conjugate surface with said pupil surface, and on the surface conjugate with said pupil surface, which is formed by said relay lens is disposed said Shack-Hartmann sensor.

4. A wavefront aberration measuring device, comprising:

a point light source forming means for forming a point light source;

a first table means for mounting said point light source forming means thereon and being movable within a plane surface;

a second table means for mounting thereon a lens to be inspected, as an object of measurement;

a Shack-Hartmann sensor for detecting light emitting from said point light source, which is formed by said point light source forming means, and transmitting through the lens to be inspected, which is mounted on said second table means;

a supporting means for supporting said Shack-Hartmann sensor thereon;

a signal processing means for processing an output signal from the Shack-Hartmann sensor detecting said light, and thereby obtaining a wavefront aberration of said lens to be inspected; and

a controlling means for controlling an entire, wherein

said supporting means has a gonio-stage for mounting said Shack-Hartmann sensor thereon and being able to oscillate around a 1-axis, and said controlling means drives said gonio-stage depending on a position of the point light source, which is formed by said point light source forming means, thereby controlling an inclination angle of said Shack-Hartmann sensor.

5. The wavefront aberration measuring device, as described in the claim 4, wherein said controlling means drives said first table means, thereby moving said point light source forming means within a substance surface of said lens to be inspected, and also drives said gonio-stage depending on distance between the point light source, which is formed by said point light source forming means, and an optical axis of the lens to be inspected, which is mounted on said second table means, thereby inclining said Shack-Hartmann sensor.

6. The wavefront aberration measuring device, as described in the claim 4, further comprising a third table means provided on said gonio-stage, wherein said supporting means supports said Shack-Hartmann sensor through said third table means, and said controlling means drives said gonio-stage depending on a position of the point light source, which is formed by said point light source forming means, thereby to control an inclination angle of said Shack-Hartmann sensor, and also drives said third table means, thereby to control a position of said Shack-Hartmann sensor.

7. A wavefront aberration measuring method, comprising the following steps of:

forming a point light source by condensing light emitting from a light source;

detecting the light emitting from said point light source and transmitting through a lens to be inspected by a Shack-Hartmann sensor; and

processing an output signal from the Shack-Hartmann sensor detecting said light transmitting through, thereby obtaining a wavefront aberration of said lens to be inspected, wherein

an inclination and a position of said Shack-Hartmann sensor or an optical path of the light transmitting through said lens to be inspected is adjusted, in such that the light emitting from said point light source and transmitting through said lens to be inspected can be detected by said Shack-Hartmann sensor, upon a pupil surface of said lens to be inspected or a surface conjugate with said pupil surface.

8. The wavefront aberration measuring method, as described in the claim 7, wherein such an adjustment of the position of said Shack-Hartmann sensor that the light transmitting through said lens to be inspected can be detected by said Shack-Hartmann sensor upon the pupil surface of said lens to be inspected or the surface conjugate with said pupil surface is executed, by mounting said Shack-Hartmann sensor on a gonio-stage so as to control an inclination angle of said gonio-stage, and thereby adjusting the inclination angle of said Shack-Hartmann sensor with respect to the pupil surface of said lens to be inspected.

9. The wavefront aberration measuring method, as described in the claim 7, wherein such an adjustment of the position of said Shack-Hartmann sensor that the light transmitting through said lens to be inspected can be detected by said Shack-Hartmann sensor upon the pupil surface of said lens to be inspected or the surface conjugate with said pupil surface is executed, by mounting said Shack-Hartmann sensor on a table, which is mounted on a gonio-stage and movable at least in one axis direction so as to control an inclination angle of said gonio-stage, thereby controlling a position of said gonio-stage by said table.

10. The wavefront aberration measuring method, as described in the claim 7, wherein such an adjustment of the position of said Shack-Hartmann sensor that the light transmitting through said lens to be inspected can be detected by said Shack-Hartmann sensor upon the pupil surface of said lens to be inspected or the surface conjugate with said pupil surface is executed, by adjusting the optical path of said light transmitting through with using a mirror being rotatable on the pupil surface of said lens to be inspected, in such that the light emitting from said point light source and transmitting through said lens to be inspected can propagate along an optical axis of said lens to be inspected, and forming a surface conjugate with said pupil surface for transmitting the light, said optical path of which is adjusted, through a relay lens, and thereby detecting said light transmitting by said Shack-Hartmann sensor, which is disposed on said conjugate surface formed.