Optical beam generating device

Abstract

The light beam generatoris provided with a laser light source, an optical phase modulation elementand others. The optical phase modulation elementreceives coherent light output from the laser light sourceand passed through a beam splitterto modulate a phase of the light depending on a position on the beam cross section of the light, and outputs the light after the phase modulation to the beam splitter. A polar coordinate system (r, θ) in which a predetermined position is given as an origin is set on the beam cross section of the light input in the optical phase modulation element, and when (p+1) domains divided by p (number of pieces) circumferences in which the predetermined position is given as a center are set, of these (p+1) domains, a phase modulation amount φ at each position inside an even numbered domain counted from the inside is expressed by a formula of 'φ=qθ', and a phase modulation amount φ at each position inside an odd numbered domain counted from the inside is expressed by a formula of 'φ=qθ+π'.