Method for adjusting compensating optical system and compensating optical system
A positional deviation between a phase distribution in a wavefront sensor and a compensation phase pattern in a wavefront modulator is corrected in a short time and with high accuracy by a method including a first step of causing the wavefront modulator to display a singularity generation pattern, a second step of measuring in the sensor an adjustment wavefront shape when an optical image modulated by the singularity generation pattern enters the wavefront sensor, a third step of detecting a position of a singularity in the adjustment wavefront shape from a measurement result in the sensor, and a fourth step of adjusting a positional deviation between a wavefront shape measured in the wavefront sensor and a compensation pattern displayed on the wavefront modulator based on a positional deviation of the position of the singularity.
1. A method for adjusting an adaptive optics system which includes a wavefront modulator receiving an optical image from a light source or an observation object, and a wavefront sensor receiving an optical image from the wavefront modulator to measure a wavefront shape of the optical image, and compensates for a wavefront distortion by controlling a pattern to be displayed on the wavefront modulator based on the wavefront shape measured by the wavefront sensor, comprising:
a first step of causing the wavefront modulator to display a singularity generation pattern which is a pattern including a singularity at a predetermined position;
a second step of measuring in the wavefront sensor an adjustment wavefront shape which is a wavefront shape when an optical image modulated by the singularity generation pattern enters the wavefront sensor;
a third step of detecting a position of the singularity in the adjustment wavefront shape from a measurement result in the wavefront sensor; and
a fourth step of adjusting a positional deviation between a wavefront shape measured in the wavefront sensor and a compensation pattern displayed on the wavefront modulator based on a positional deviation of the position of the singularity detected in the third step with respect to the predetermined position.
2. The method for adjusting an adaptive optics system according to claim 1 , wherein, in the third step, in the adjustment wavefront shape, a closed-path integration value of a phase gradient is calculated for each of the unit regions composing the wavefront sensor, and a position of the unit region where the closed-path integration value peaks (hereinafter, referred to as a peak position) is determined to detect the position of the singularity assuming that the singularity is included in the unit region of the peak position.
3. The method for adjusting an adaptive optics system according to claim 2 , wherein the position of the singularity within the unit region of the peak position is calculated based on the closed-path integration values of the unit regions located around the peak position.
4. The method for adjusting an adaptive optics system according to claim 1 , wherein the wavefront sensor is a Shack-Hartmann type wavefront sensor.
5. The method for adjusting an adaptive optics system according to claim 1 , wherein the singularity generation pattern has a spiral wavefront shape.
6. An adaptive optics system comprising:
a wavefront modulator receiving an optical image from a light source or an observation object;
a wavefront sensor receiving an optical image from the wavefront modulator to measure a wavefront shape of the optical image; and
a control section compensating for a wavefront distortion by controlling a pattern to be displayed on the wavefront modulator based on the wavefront shape measured by the wavefront sensor, wherein
the control section includes:
a singularity generation pattern preparing section causing the wavefront modulator to
display a singularity generation pattern which is a pattern including a singularity at a predetermined position; and
a singularity detecting section detecting a position of the singularity in an adjustment wavefront shape which is a wavefront shape when an optical image modulated by the singularity generation pattern enters the wavefront sensor, based on a measurement result in the wavefront sensor, and
the control section adjusts a positional deviation between a wavefront shape measured in the wavefront sensor and a compensation pattern displayed on the wavefront modulator based on a positional deviation of the position of the singularity detected by the singularity detecting section with respect to the predetermined position.
7. The adaptive optics system according to claim 6 , wherein the singularity detecting section, in the adjustment wavefront shape, calculates a closed-path integration value of a phase gradient for each of the unit regions composing the wavefront sensor, and determines a position of the unit region where the closed-path integration value peaks (hereinafter, referred to as a peak position) to detect the position of the singularity assuming that the singularity is included in the unit region of the peak position.
8. The adaptive optics system according to claim 7 , wherein the singularity detecting section calculates the position of the singularity within the unit region of the peak position based on the closed-path integration values of the unit regions located around the peak position.
9. The adaptive optics system according to claim 6 , wherein the wavefront sensor is a Shack-Hartmann type wavefront sensor.
10. The adaptive optics system according to claim 6 , wherein the singularity generation pattern has a spiral wavefront shape.