OPTICAL SYSTEM AND DEVICE USING DIFFRACTION OPTICAL ELEMENT

摘要

PROBLEM TO BE SOLVED: To satisfactorily correct a color aberration in a wide wavelength area and to obtain a high resolution performance within a wavelength area to be used. SOLUTION: An optical system uses a diffraction optical element 11 having diffraction efficiency which is optimized on the short-wavelengths side rather than at the central wavelength in a wavelength area used as the entire optical system. The diffraction efficiency of the diffraction optical element 11 is optimized on the short wavelength side where the degree of decrease in diffraction efficiency is high. Consequently, even in use in a wide wave-length area, image resolution performance sufficient from the short wavelength side to the long wavelength side is obtained. It is preferable that the diffraction optical element 11 satisfy a conditional expression given below: 0.15≤(λdoe-λmin)/(λmax-λmin)≤0.40...(1), whereinλdoeis the optimum wavelength of the diffraction optical element 11,λminis the shortest wavelength in the wavelength area used as the entire optical system, andλmaxis the longest wavelength in the wavelength area used as the entire optical system. COPYRIGHT: (C)2011,JPO&INPIT