| 摘要 |
PURPOSE:To avoid damaging a hologram which is obtd. when two wave surfaces are interfered by prescribed laser light and to facilitate production by providing said hologram on the outside peripheral surface of a transparent rotary member embedded with an opaque member serving as a revolving shaft in the central part. CONSTITUTION:A photosensitive agent, such as silver salt, is coated on the outside peripheral surface of a transparent rotary member 11 having a transparent circular truncated cone shape. A hologram 14 is formed thereon by making a plane wave 12 and spherical wave 13 of laser light incident thereto and interfering the two wave surfaces. An opaque metallic member 15 is embedded in the central part of said member and a revolving shaft 16 is attached thereto. When the member 11 is rotated and the spherical wave of laser light is irradiated from a laser light source 18 to the hologram 14, the plane wave 19 which is the other wave formed by the hologram is emitted. If the laser light emitted in such a way is projected, via an ftheta lens 20, to a screen 21, the beam light projected thereon is corrected and the spot image of the reduced beam diameter is projected thereon. |
