When {HEAD ~ areas} sectioned by p circumferences centered on a predetermined position are set on {TAIL ~ a beam cross section} of light input to the optical phase modulator 15, the more outside each of the areas is, the wider the radial width of the area, the amount of phase modulation is constant in each of the areas, and the amounts of phase modulation differ by π between two adjacent areas out of the areas 
When { HEAD ~ areas } sectioned by p circumferences centered on a predetermined position are set on { TAIL ~ a beam cross section } of light input to the optical phase modulator 15 , the more outside each of the areas is , the wider the radial width of the area , the amount of phase modulation is constant in each of the areas , and the amounts of phase modulation differ by π between two adjacent areas out of the areas
OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH