Optical material, and, optical element, optical system and laminated diffractive optical element using it

摘要

An optical element of which diffraction efficiency hardly varies with wavelength is provided by using an optical material satisfying the conditions that nd>-6.667x10<-3>v<d>+1.70 and thetag,F<=-2x10<-3>vd+0.59 where nd is a refractive index at d-line, vd is an Abbe number at the d-line, and thetag,F is a second order dispersion at d-line, whereby diffraction efficiency is improved in any working visible wavelength region and more precise chromatic aberration correction is obtained.