Patent ID: 6081384
Filing Date: 2000-06-27
Classification: G02B

Abstract:
A color-corrected and temperature-compensated lens comprising a lens system including a lens made of anomalous dispersion glass for correcting a secondary spectrum of axial chromatic aberration and a plastic lens having a temperature-compensating characteristic for correcting defocusing upon change of said lens system with respect to temperature; whereinsaid lens satisfies the following conditional expression (3): ##EQU3## wherein .PHI..sub.i is a refracting power of each lens; h.sub.i is a height of a ray passing through each lens when each lens is substituted by a thin lens and subjected to ray tracing with respect to a center luminous flux thereof;.chi..sub.i is a coefficient determined by:.chi.=.alpha.-dn/dt.multidot.1/(n-1)where a coefficient of linear expansion of a material is .alpha., a refractive index thereof is N, and change in refractive index thereof with respect to change in temperature is dn/dt; andsuffixes p, and ed respectively refer to a plastic lens, and an anomalous dispersion lens having a level of dispersion .nu.=60 or higher and a temperature coefficient .chi.=9.0 or higher.