Patent ID: 8553733

Claim:
A light source device comprising: a light source for outputting coherent light; and an optical phase modulator for inputting the light output from the light source, phase-modulating the light according to a position on a beam cross section of the light, and outputting the phase-modulated light, wherein when (p+1) areas sectioned by p circumferences centered on a predetermined position are set on a beam cross section of the light input to the optical phase modulator, p being a natural number and being greater than or equal to 2, the more outside each of the (p+1) areas is, the wider the radial width of the area, an amount of phase modulation is constant in each of the (p+1) areas, and the amounts of phase modulation differ by t between two adjacent areas out of the (p+1) areas, and wherein the radial width is defined as a difference between radii of an exterior border and an interior border of a respective area.