PHASE MODULATION METHOD AND PHASE MODULATING DEVICE

摘要

A phase distribution is calculated such that modulated light has a predetermined intensity distribution on a target plane and displayed on a phase modulation plane, readout light enters the phase modulation plane so as to generate the modulated light. When calculating the phase distribution, a region on the phase modulation plane is divided into N regions A1 . . . AN, with sizes set such that integration values of an intensity distribution in the regions are equal to each other. Further, a region on the target plane is divided into N regions B1 . . . BN, with sizes set such that integration values of an intensity distribution in the regions are equal to each other. The phase distribution is calculated by obtaining an optical path length from the region An to the region Bn, and determining the phase of the region An based on the optical path length.

主权项

1. A phase modulation method for modulating readout light, of which an intensity distribution in an arbitrary section including an optical axis is axially symmetric with respect to the optical axis, in phase in each of the plurality of regions to generate modulated light, using a spatial light modulator comprising a phase modulation plane including a plurality of two-dimensionally arrayed regions, comprising:
a phase distribution calculation step of calculating a phase distribution to be displayed on the phase modulation plane such that the modulated light has a predetermined intensity distribution on a target plane separated by a predetermined optical distance from the phase modulation plane; and a modulated light generation step of displaying the phase distribution on the phase modulation plane, and causing the readout light to enter the phase modulation plane so as to generate the modulated light, wherein the phase distribution calculation step comprises: a step of dividing a region on the phase modulation plane which the readout light enters into N (N is an integer of 2 or more) concentric regions A1 . . . AN centered on an optical axis of the readout light and setting sizes of the regions A1 . . . AN such that integration values of an intensity distribution in the regions A1 . . . AN in a section including the optical axis of the readout light are equal to each other, and dividing a region on the target plane into N concentric regions B1 . . . BN centered on an optical axis of the modulated light and setting sizes of the regions B1 . . . BN such that integration values of an intensity distribution in the regions B1 . . . BN in a section including the optical axis of the modulated light are equal to each other; and a step of calculating the phase distribution by obtaining an optical path length Ln from the region An to the region Bn (n is each integer from 1 to N), and determining a phase of the region An based on the optical path length Ln.