Illuminating device using coherent light source

摘要

A laser beam (L50) is reflected by a light beam scanning device (60), and irradiated onto a hologram recording medium (45) where an image (35) of a scatter plate is recorded as a hologram by using reference light that converges on a scanning origin (B). The light beam scanning device (60) bends the laser beam (L50) at the scanning origin (B). Scanning is effected by changing the bending mode of the laser beam so that the irradiation position of the bent laser beam (L60) on the hologram recording medium (45) changes with time. Regardless of the beam irradiation position, diffracted light (L45) from the hologram recording medium (45) reproduces the same reproduction image (35) of the scatter plate at the same position. An illumination spot with reduced speckles is formed on the surface (R) of an illuminating object (70) by the reproduction image (35) of the hologram.

主权项

1. An illumination apparatus using a coherent light source, comprising:
a coherent light source (50) that generates a coherent light beam (L50); a hologram recording medium (45, 46, 85) on which an image (35) of a scatter plate (30) is recorded; and a light beam scanning device (60, 65) that irradiates the light beam (L60, L65) onto the hologram recording medium (45, 46, 85), and scans the light beam (L60, L65) so that an irradiation position of the light beam (L60, L65) on the hologram recording medium (45, 46, 85) changes with time, wherein the image of the scatter plate (30) is recorded as a hologram on the hologram recording medium (45, 46, 85) as a form of interference fringes which reproduce the image of the scatter plate (30) when respective light beams (L61, L62) are given as illumination light advancing toward respective one points (P1, P2) within the medium along respective particular optical paths so that reproduction images (35) are identical to each other and produced at a same position, the coherent light source (50) generates a light beam (L50) with a wavelength capable of reproducing the image (35) of the scatter plate, the light beam scanning device (60, 65) scans the generated light beam (L60, L65) so that an irradiation direction of the generated light beam (L60, L65) with respect to the hologram recording medium (45, 46, 85) is along one of said particular the optical paths, and reproduction light of the image (35) of the scatter plate (30) obtained from the hologram recording medium (45, 46, 85) is used as illumination light.