| 摘要 |
PROBLEM TO BE SOLVED: To provide an illumination device that can effectively make speckle inconspicuous.SOLUTION: An optical element 50 includes hologram elements 55a, 55b for diffracting corresponding coherent light La, Lb. The coherent light La, Lb diffracted by the hologram elements 55a, 55b illuminate at least a region LZ to be illuminated. When the angles which, with respect to the traveling directions of the coherent light La, Lb incident upon the hologram elements 55a, 55b, the traveling directions of the coherent light La, Lb diffracted by the hologram elements 55a, 55b and traveling to the region LZ to be illuminated form angles defined as ψa,ψb, the maximum of absolute value of ψa is lower than the maximum of absolute value of ψb. |
