| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element, optical device, lighting device, image display device, and exposure device which reduce spatial coherence or speckles. SOLUTION: A 1st reflecting surface 5 has reflecting surfaces 5a disposed in parallel to one another at constant intervals (d) while slanting at about 45 deg. to the optical axis of incident coherent light and a 2nd reflecting surface 7 has reflecting surface 7a disposed in parallel to one another at constant intervals (d) while slanting at about 45 deg. to the optical axis of reflected light on the 1st reflecting surface 5; and the incident coherent light is reflected by the 1st reflecting surface 5 and 2nd reflecting surface 7 to generate luminous flux consisting of areas having constant optical path differences in order and branch light is emitted from the 2nd reflecting surface 7. |
