DEFORMABLE MIRROR SYSTEM, CONTROL METHOD THEREFOR, AND OPHTHALMIC APPARATUS

• US 20160089023A1
• Filed: 09/02/2015
• Published: 03/31/2016
• Est. Priority Date: 09/25/2014
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Takeno, Kohei, Ohashi, Kaishi
• Granted Patent: US 10,925,485 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 3/1015 for wavefront analysis
• CPC Class Codes: A61B 3/12 for looking at the eye fundus, e.g. ophthalmoscopes A61B3/13 takes precedence
• CPC Class Codes: A61B 3/14 Arrangements specially adapted for eye photography apparatus or arrangements for taking photographs per se G03B
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 26/0825 the reflecting element being a flexible sheet or membrane, e.g. for varying the focus flexible mirrors for cosmetic use A45D42/24

Abstract

For reducing a time utilized in an AO process, provided is a deformable mirror system, including: a deformable mirror capable of changing a shape of a reflecting surface by a deformation amount in accordance with an input signal; a light wavefront measurement apparatus configured to measure a light wavefront shape of reflected light from the deformable mirror; a conversion factor calculation apparatus configured to calculate a conversion factor used in obtaining the input signal from a variation in light wavefront shape of the reflected light with respect to a change in input signal; a shape difference calculation apparatus configured to calculate a shape difference between the light wavefront shape measured by the light wavefront measurement apparatus and a light wavefront shape calculated from the input signal; and a conversion factor update unit configured to update the conversion factor in accordance with the calculated shape difference.

Claims

1. A deformable mirror system, comprising:

a deformable mirror capable of changing a shape of a reflecting surface by a deformation amount in accordance with an input signal;

a light wavefront measurement unit configured to measure a light wavefront shape of reflected light from the deformable mirror;

a conversion factor calculation unit configured to calculate a conversion factor used in obtaining the input signal from a variation in light wavefront shape of the reflected light with respect to a change in input signal;

a shape difference calculation unit configured to calculate a shape difference between the light wavefront shape measured by the light wavefront measurement unit and a light wavefront shape based on the input signal; and

a conversion factor update unit configured to update the conversion factor in accordance with the calculated shape difference.

2. A deformable mirror system according to claim 1, wherein the conversion factor update unit is configured to update the conversion factor based on a result of a comparison between the shape difference and a threshold value.

3. A deformable mirror system according to claim 2, further comprising a threshold value changing unit configured to change the threshold value in accordance with the update of the conversion factor by the conversion factor update unit.

4. A deformable mirror system according to claim 1, wherein the conversion factor update unit is configured to update the conversion factor in a predetermined value range with respect to an operating point of the deformable mirror at which the reflected light from the deformable mirror starts to have the light wavefront shape calculated based on the input signal.

5. A deformable mirror system according to claim 1, wherein the conversion factor update unit multiplies the conversion factor by a constant.

6. A deformable mirror system according to claim 1, further comprising:

a defocus amount detection unit configured to detect a defocus amount with respect to an object to be inspected on which the reflected light is reflected; and

an image capturing permission unit configured to permit, in accordance with a result of a comparison between the detected defocus amount and a defocus reference value, an image of the object to be inspected to be captured based on the reflected light.

7. A deformable mirror system according to claim 6, further comprising:

a residual defocus amount calculation unit configured to calculate a residual defocus amount based on the detected defocus amount and the defocus amount calculated from the input signal; and

a residual defocus reference value update unit configured to compare the calculated residual defocus amount and a residual defocus reference value to update the residual defocus reference value.

8. An ophthalmic apparatus, comprising the deformable mirror system according to claim 6, wherein the object to be inspected comprises an eye, and

wherein the image comprises an image of a fundus of the eye.

9. A control method for a deformable mirror system, comprising:

changing a shape of a reflecting surface of a deformable mirror by a deformation amount in accordance with an input signal;

measuring a light wavefront shape of reflected light from the deformable mirror;

calculating a conversion factor used in obtaining the input signal from a variation in the light wavefront shape of the reflected light with respect to a change in the input signal;

calculating a shape difference between the measured light wavefront shape and a light wavefront shape calculated based on the input signal; and

updating the conversion factor in accordance with the calculated shape difference.

10. A recording medium having recorded thereon a program for causing a computer to execute each of steps of a control method for a deformable mirror system, the control method comprising:

changing a shape of a reflecting surface of a deformable mirror by a deformation amount in accordance with an input signal;

measuring a light wavefront shape of reflected light from the deformable mirror;

calculating a conversion factor used in obtaining the input signal from a variation in the light wavefront shape of the reflected light with respect to a change in the input signal;

calculating a shape difference between the measured light wavefront shape and a light wavefront shape calculated based on the input signal; and

updating the conversion factor in accordance with the calculated shape difference.