Optical modulation control method, control program, control device, and laser light irradiation device

摘要

In controlling light condensing irradiation with laser light using a spatial light modulator, an incident pattern of the laser light and respective refractive indices of first and second propagation media on a propagation path are acquired, the number of light condensing points, and the light condensing position and the light condensing intensity at each light condensing point are set, an aberration condition caused by the first and second propagation media is derived, and by taking the aberration condition into account, a modulation pattern to be presented in the spatial light modulator is designed. Further, in designing the modulation pattern, a design method focusing on an effect of a phase value at one pixel is used, and in evaluating the light condensing state at the light condensing point, a propagation function that takes the aberration condition into account is employed.

主权项

1. A light modulation control method by use of a phase-modulation type spatial light modulator that inputs laser light thereto and then modulates the phase of the laser light so as to output the phase-modulated laser light and which controls light condensing irradiation onto a set light condensing point with the laser light by a modulation pattern to be presented in the spatial light modulator, the light modulation control method comprising:
an irradiation condition acquiring step of acquiring, as an irradiation condition for the laser light, an incident pattern of the laser light to the spatial light modulator, a first refractive index n1 of a first propagation medium on a propagation path of the laser light from the spatial light modulator to the light condensing point, and a second refractive index n2 of a second propagation medium located to be closer to the light condensing point side than the first propagation medium, the second refractive index being different from the first refractive index; a light condensing condition setting step of setting, as a light condensing condition for the laser light, the number st of the light condensing points for light condensing irradiation with the laser light from the spatial light modulator (st is an integer of 1 or more), and the light condensing position and the light condensing intensity of each of the st light condensing points s; an aberration condition deriving step of deriving an aberration condition that is caused by the first propagation medium and the second propagation medium, which have refractive indices different from each other, in the propagation of the laser light from the spatial light modulator to the light condensing point s; and a modulation pattern designing step of designing the modulation pattern to be presented in the spatial light modulator by taking into account the aberration condition derived in the aberration condition deriving step, wherein in the modulation pattern designing step, assuming a plurality of two-dimensionally arrayed pixels in the spatial light modulator and focusing on an effect on a light condensing state of the laser light at the light condensing point by a change in a phase value at one pixel of the modulation pattern to be presented in the plurality of pixels, the phase value is changed so that the light condensing state is brought closer to a desired state, and such phase value changing operations are performed on all pixels of the modulation pattern to thereby design the modulation pattern, and in evaluating the light condensing state at the light condensing point, a propagation function φjs′ is employed for the propagation of light from a pixel j of the modulation pattern in the spatial light modulator to the light condensing point s, the propagation function being converted from a wave propagation function φjs for free propagation through a homogeneous propagation medium by adding the aberration condition thereto.