US 5,841,590 A · Aberration controllable optical system

Abstract

An aberration-controllable optical system has a large angle of view and is capable of continuously varying spherical aberrations from negative values to positive values, including a point at which a sharp image can be produced. A master lens group includes a first sub lens group having a positive refractive power, a second sub lens group having a negative refractive power, and a third sub lens group having a positive refractive power in this order from the object side of the system. The converter lens group includes a positive lens element and a negative lens element in this order from the object side. The on-axis distance of the air gap which is formed between the positive lens element and the negative lens element can be controlled to mainly change the spherical aberrations in this system. When f.sub.m is a master lens group focal length and f.sub.C is a converter lens group focal length, the aberration-controllable optical system satisfies a condition: -1<f.sub.M /f.sub.C <0. The master lens group can include a front group and a rear group. Focusing at a short distance may be conducted by moving the front lens group and the rear group independently of each other.

Claims25

Dependent claims

An aberration-controllable optical system comprising:

a master lens G.sub.M group having a positive refractive power, and
a converter lens G.sub.C group having a negative refractive power, said master lens group and said converter lens group arranged in order from an object side of the system,
the master lens group including a first sub lens group L1 with a positive refractive power, a second sub lens group L2 with a negative refractive power, and a third sub lens group L3 with a positive refractive power in order from the object side of the system,
the converter lens group including a positive lens element L.sub.P with a positive refractive power and a negative lens element LN with a negative refractive power in order from the object side, the positive lens element L.sub.P and the negative lens element L.sub.N forming an air gap therebetween that has a concave surface facing an aperture stop,
an on-axis air gap distance between the positive lens element and the negative lens element being varied to change mainly spherical aberrations,
the aberration-controllable optical system satisfying a condition:
-1<f.sub.M /f.sub.C <0
when f.sub.M is a focal length of the master lens group during focusing an infinity object and f.sub.C is a focal length of the converter lens group during focusing an infinity object and at a lens position with minimum spherical aberrations.

5 more elements

A variable aberration optical system comprising:

a master lens group G.sub.M having positive refractive power and
a converter lens group G.sub.C having negative refractive power, the master lens group and the converter lens group being arranged in order from an object,
wherein the master lens group G.sub.M includes a first portion lens group L.sub.1 having positive refractive power, a second portion lens group L.sub.2 having negative refractive power and a third portion lens group L.sub.3 having positive refractive power and arranged in order from the object,
wherein the converter lens group includes a positive lens element L.sub.P having positive refractive power and a negative lens element L.sub.N having negative refractive power, a space formed between the positive lens element L.sub.P and the negative lens element L.sub.N is arranged so that a concave surface of the space faces an aperture stop, and an axial distance of the space between the positive lens element L.sub.P and the negative lens element L.sub.N is variable so as to vary mainly spherical aberration, and
wherein the master lens group includes a front group G.sub.A and a rear group G.sub.B arranged in order from the object, and the front group G.sub.A and the rear group G.sub.B are moved independently of each other so that focusing on the object located at a short distance is conducted.

2 more elements

Dependencies are inferred from the claim text.

Aberration controllable optical system

Life of this patent

Aberration controllable optical system

Life of this patent

Abstract

Claims25