| 摘要 |
PROBLEM TO BE SOLVED: To provide an achromatic lens system or the like which is light in weight and is easily manufactured and whose spherical aberrations are corrected satisfactorily, simultaneously with chromatic aberrations. SOLUTION: The achromatic lens system has: a resin doublet which is constituted by cementing a resin lens L11, having positive refractive power and a resin lens L12 having negative refractive power, and has positive refractive power as a whole; and a contact multilayer type diffraction optical device L11E. The diffraction optical device L11E is arranged on the image side of the cemented resin lens, and is constituted by cementing two diffraction device elements DE11 and DE12 composed of different optical material, and its cemented surface is a diffraction optical surface Gf, where a diffraction grating groove is formed. COPYRIGHT: (C)2008,JPO&INPIT
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