An optical element of which diffraction efficiency hardly varies with wavelength is provided by using an optical material satisfying the conditions that nd-6.66710-3d+1.70 and g,F-210-3d+0.59 where nd is a refractive index at d-line, d is an Abbe number at the d-line, and g,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.

 
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