Light source device for scanning-exposure and method and apparatus for scanning-exposure

摘要

A blue laser light source is a semiconductor laser having a sapphire substrate that is transparent to a wavelength of a blue laser beam emitted from an active layer. A condenser lens converges the blue laser beam at a focal point where a modulator is placed. A slit plate limits the light flux on the exit side of the condenser lens. A slit of the slit plate is located at a depth position (Z) on an optical axis of the condenser lens, and the depth position satisfies the following conditions: Z>=Z 0 (Z 0<0 ) and Pp(Z 0 )=P 1, wherein Z is assumed to have a positive value on a forward side of the blue laser beam from the focal point, Pp(Z) is a value obtained by dividing a width of the blue laser beam in the parallel direction to the active surface at the depth position Z by a width of the extraneous light in the parallel direction at said depth position, and P 1 is a convergent value of Pp(Z) at the infinity (Z->∞).