| 摘要 |
PROBLEM TO BE SOLVED: To display a stable low pass effect and to obtain a satisfactory picture at the time of using the optical low pass filter(LPE) for an optical instrument by regulating the ratio of wave front aberrations on a prescribed position in a diameter direction generated in a passing luminous flux and a ratio of variation amts. of wave front aberrations. SOLUTION: A wave front aberration W (ρ,ϕ)=Wr(ρ)×Wt(ϕ) is generated on the wave front of a luminous flux passing through the LPF in terms of the cylindrical coordinate system (ρ,ϕ) with its origin set up at the center of the incident luminous flux, withρandϕrepresenting coordinated in the vadial and rotational directions. Here, Wr(ρ) is a function expressing the wave front aberration in the radial direction and Wt(ϕ) is the function expressing the wave front aderration in the rotational direction. Theρis the radius of the effective part of the filter and is is assumed to be by 0<=ρ<=1, andϕis given by 0<=ϕ<=2π. The optical LPF is set up so that the ratio of wave front aberrations Wr(ρ) on prescribed positions satisfies the conditions of Wr(0.3)/Wr(0.6)>0 and Wr(0.6)/Wr(0.9)>0.
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