| 摘要 |
PROBLEM TO BE SOLVED: To resolve the problem that the optical capacity is degraded by a minute transmission wave surface phase difference of an ND filter. SOLUTION: In a light quantity controller provided with an ND filter P1 for attenuating the quantity of light passing through an opening formed by sectors S11 and S12, the ND filter P1 is so set that the phase difference of light having a prescribed wavelengthλ, which passes through areas different in transmittance (an area wherein only N11 exists and an area wherein both N11 and N12 exist, in the optical path), may be within the range of ä1±(1/5)}λor ä2±(1/5)}λ. COPYRIGHT: (C)2003,JPO
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