| 摘要 |
PROBLEM TO BE SOLVED: To enhance contrast of a signal light from a diffraction grating type spatial light modulator. SOLUTION: An optical head 10 includes: a first optical system 12a, a slit member 125, and a second optical system 12b in an illumination optical system 12 for generating a linear illumination light to the diffraction grating type spatial light modulator 13. A light from a laser light source 11 is collected at a position of a slit 125a in a vertical direction by the first optical system 12a to form an intermediate image which is long in a lateral direction corresponding to an arrangement direction of light modulator elements. An unwanted light such as side lobes which appear on the both sides of the intermediate image in the vertical direction is blocked by a slit 125a, and the intermediate image is formed again by the second optical system 12b, to guide a linear illumination light having a narrow width onto the spatial light modulator 13. Thus, when flexible ribbons are sagged and first order diffracted light is emitted in a light modulator element, zeroth order light is prevented from being emitted from both end portions of ribbons, to thereby enhance contrast of the signal light. COPYRIGHT: (C)2011,JPO&INPIT |
