Ricoh FT6645 Manual page 67

OPTICS
3.10 UNEVEN LIGHT INTENSITY CORRECTION
[D]
original
Shading plate
The entire exposure lamp surface is frosted to ensure even exposure.
To compensate for reduced light at the edge of the lens, a shading plate is
placed in front of the lens. The shading plate is fixed to the lens unit.
The shading plate compensates the light intensity when the lens horizontal
position is shifted ([A] to [C]).
Also three shading mylars [D] intercept any diffused reflected light from
outside the light path.
[D]
[A] [B] [C]
[A] [B]
2-42
[D]
exposure
intensity
[C]
23 April 1993
illumination
distribution