| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an apparatus of a simple constitution for continuously measuring the conjugate position of a face inclination correction type light scanning optical system using a polygon mirror. SOLUTION: While moving a triangular slit 21, which has an opening width continuously changing in a sub scanning direction along main scanning directions each at locations in front and in the back of a surface assumed as a surface to be scanned separated by a prescribed distance H, in the main scanning directions at a relatively slow speed in comparison with the moving speed of a scanning light beam B2, optical quantity passing through the triangular slit 21 is photoelectrically converted to generate pulse signals. Pulse width variation width dataδt1 andδt2 at each oration of the polygon mirror 4 is acquired from the pulse signals according to the position in the main scanning directions of the triangular slit 21. On the basis of the relation between the pulse width variation width dataδt1 andδt2 and S=H×(δt1-δt2)/(δt1+δt2), the position S of a conjugate point of the light scanning optical system 10 to the surface to be scanned on the main scanning directions is continuously determined in the measuring method and the apparatus. COPYRIGHT: (C)2006,JPO&NCIPI
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