Patent ID: 7729226
Filing Date: 2010-06-01
Classification: G11B

Abstract:
1. A wavefront aberration compensation element comprising: a wavelength selection phase plate having a plurality of phase steps of various widths and various thicknesses at various areas; a liquid crystal layer for obtaining a prescribed wavefront aberration; and a pair of first and second electrode layers having the liquid crystal layer disposed therebetween, wherein either one of the wavelength selection phase plate and the pair of first and second electrode layers having the liquid crystal layer disposed therebetween is stacked on the other, wherein a phase step of a single area of the wavelength selection phase plate satisfies a relation of “nd=mλ1” with respect to a light beam of a predetermined wavelength, wherein “d” represents the phase step of a single area of the wavelength selection phase place, “λ1” represents the light beam of a predetermined wavelength, “n” represents a refractive index and “m” represents a given integral number, wherein the liquid crystal layer comprises a plurality of liquid crystal cells arranged in correspondence with the widths of the plurality of phase steps in the wavelength selection phase plate such that a width of each of the plurality of liquid crystal cells is substantially the same as the width of the corresponding one of the plurality of phase steps in the wavelength selection phase plate, and wherein the liquid crystal layer provides a wavefront aberration in an opposite direction with respect to a residual aberration generated by a light transmittal through the wavelength selection phase plate.