ULTRA-WIDE VISUAL FIELD ACHROMATIC OBJECTIVE LENS

摘要

PURPOSE: To provide an achromatic objective lens whose magnification is about 10 and acting distance is ≥10mm, and having a comparatively large numerical aperture and excellent aberration even in the case of a ultra-wide visual field. ;CONSTITUTION: This lens is provided with a first lens group G₁, including at least one positive lens and having positive refractive power as a whole, a second lens group G₂ obtained by sticking the positive lens whose convex surface is made to face the object side and a negative lens whose concave surface is made to face the image side, a third lens group G₃ obtained by sticking the negative lens whose concave surface is made to face the object side and the positive lens whose convex surface is made to face the image side and a fourth lens group G₄ having the positive refractive power in turn from the object side. Then, the proper refractive power of the first lens group G₁ and the refractive index and the dispersion of the respective lenses are regulated.;COPYRIGHT: (C)1995,JPO