| 摘要 |
<p>In a refraction lens having an aspheric shape formed thereon and having a positive power, a diffraction grating is formed on at least one of the faces of the refraction lens. In order to reduce the curvature of field and the chromatic aberration in a well-balanced manner, the zonal pitch of the diffraction grating is constituted so as to satisfy the following conditional expression. [ eq . 19 ] 0.21 m 2 v d λ f h max <Λmin < 0.30 m 2 v d λ f h max ( 1 ) Herein,Λmin is a minimum zonal pitch 12; m is an order of diffraction;νd is an Abbe number of the lens substrate material with respect to the d-line;λis a wavelength; f is an effective focal length; and hmax is an effective radius 13 of the face on which the diffraction grating is formed.</p> |
