| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an optical scanner retaining high light-use efficiency and suppressing fluctuation in the light use efficiency in a main scanning direction. <P>SOLUTION: A light source unit is configured to emit a luminous flux of longitudinal polarization light and a luminous flux of transverse polarization light, and the two luminous fluxes are polarized by a polygon mirror and then separated by a luminous flux separating element. A beam separation surface of the luminous flux separation element is a dielectric multilayer film, satisfies the following relation: Tp<SB POS="POST">0</SB>+Rs<SB POS="POST">0</SB>)/2<(Tp<SB POS="POST">1</SB>+Rs<SB POS="POST">1</SB>)/2 and is designed such that (Tp+Rs)/2 monotonically increases as an incident angleθincreases. In this case, both of a transmittance of the longitudinal polarization light and a reflectivity of the transverse polarization light in the beam separation surface are defined as 0.89 (=89%) or more and are substantially uniformized irrelevant to the incident angleθ. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
