| 摘要 |
PROBLEM TO BE SOLVED: To provide an image exposure device in which stray light emitted from a light source which emits much stray light is suppressed. SOLUTION: The numerical aperture number of a focusing optical system (collimator lens) 72 is so decided that the ratio R satisfies the relation 2.0≥R≥0.58, where the ratio R is defined by R=(sin<SP>-1</SP>NA)×2/θand R stands for the ratio of the total angleϕof the diversion angle of light of a laser light source (GaN based semiconductor laser) 211B at half-value intensity and the total angle 2θof the divergent angle of the light which defines the numerical aperture number NA of the focusing optical system (collimator lens) 72. COPYRIGHT: (C)2003,JPO
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