Lens system having diffracting surface and refracting surface and optical apparatus using the lens system

摘要

In a lens system having one or a plurality of diffracting surfaces and one or a plurality of refracting surfaces, a power of each surface and a distance between the surfaces are set such that an optical characteristic of the lens system, such as a focal length (focal point) and/or a spherical aberration, remains substantially unvarying relative to temperature variations within a predetermined range and that an achromatic effect is substantially attained for the focal length (focal point) and/or the spherical aberration within a predetermined region of wavelength. <IMAGE>