| 摘要 |
PURPOSE: To provide a phase lattice minimized in zero-order diffraction efficiency to natural radiant light beam and a high reliable optical encoder using the phase lattice. CONSTITUTION: The phase lattice has a depth higher than depth (d') calculated by an equation,|n-n0|×(p-d'/e)/p×d'=(λ/2)×(1+2m) (where, m=0,±1,±2,...), using wave length (λ) of light, pitch length (p) of the phase lattice, refractive index (n) of a base material of the phase lattice, refractive index (n0 ) of a medium around the phase lattice and shape ratio (e) of the depth of the phase lattice to the width of an inclined part of the recessed part.
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