| 摘要 |
PURPOSE:To maintain a physical size interval between a semiconductor laser and a collimating lens in a constant state by surrounding a supporting member by a heat insulating member, also holding the supporting member at a fixed temperature, and cutting off thermally an opening of an optical path by a 1/2 wavelength plate having a heat insulating property, when holding the supporting member by the heat insulating member. CONSTITUTION:A spacer 10 is surrounded by the first heat insulating member 19 and the second heat insulating member 20 of a cylindrical shape, and also a flange 12 is surrounded by the second flange 21 consisting of a heat insulating member such as a synthetic resin, etc. On this second flange 21, an opening is formed in order to secure an optical path of a laser light, and in order to cut off thermally this opening, a 1/2 wavelength plate 22 is utilized. In case when a holo-scanner is used as a scanning means, this 1/2 wavelength plate 22 has a function for rotating a plane of polarization of a laser light by 90 deg. to match a lattice direction of a hologram in order to raise a diffraction efficiency by the hologram. Also, the spacer 10, the flange 12, a semiconductor laser LD, etc. which become an object of a temperature control are surrounded by the heat insulating member, and are scarcely influenced by a temperature variation from the outside, the burden of a Pertier effect element 15 is reduced, and the fixed temperature holding function is raised. |
