| 摘要 |
PURPOSE:To reduce the influence of the cutting of a scanning surface upon the shape of a spot scanning on a screen and to reduce a subscanning-direction irregularity due to the distortion of the spot shape by controlling light other than the light of 0th order of an optical scanner. CONSTITUTION:A laser beam 2 from a laser light source 1 is compressed by a beam compressor 3 to a proper beam diameter, its intensity is A/O-modulated 4, and the projection diameter is varied by a beam expander 5 to the image formation size of a recording film 11. This light beam is made incident on a polygon mirror 9 through a reflecting mirror 6 and a cylindrical lens 7. A beam B from this rotating mirror 9 is made incident on an Ftheta lens 10 to scan the film 11 on a rotary drum 12. A half-mirror M1 is arranged between this lens 7 and mirror 9 and a half-mirror M2 is arranged on the optical path of the beam B from the mirror 9. Then a light beam size control means 5 prevents light which is incident on and diffracted by the lens 10 according to the pitch of the mirror 9 except the light of 0th order from being mixed. |
