| 摘要 |
PROBLEM TO BE SOLVED: To change a beam profile in the vicinity of a focus position while satisfying necessary optical characteristics.SOLUTION: A light source unit 1 includes: a laser light source 11; a collimator lens 12; a phase modulation element 13 that is arranged between the laser light source and the collimator lens; and an image formation optical system 15. In the phase modulation element 13, a movement mechanism 16 is provided that moves the phase modulation element 13 along an optical axis AX direction. The movement of the phase modulation element 13 allows for a change of a beam profile of an optical image formed in the vicinity of a focal plane FS (a focus position) by the image formation optical system 15. Thus, in the vicinity of the focus position, a beam diameter, depth of focus or beam waist position can be adjusted. |
