# US 4,391,621 A · Method of making lenses having a spherical face

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- Number: US 4,391,621 A
- Document ID: US4391621A
- Status: Granted
- Kind: A
- Application number: 06/246,551
- Filed: 1981-03-23
- Granted: 1983-07-05
- Earliest claimed: 1981-03-23
- Assignees: American Optical Corporation
- Inventors: Walter P. Siegmund
- Web page: https://patentgrep.com/patent/US4391621A

## CPC

- C03B 23/047: by drawing ({C03B23/091} , C03B37/025 takes precedence)
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

## Abstract

A lens is formed of a section of glass clad glass rod ground and polished to a spherical shape of radius of curvature equal to that desired of a face of the lens. Remaining leachable cladding glass is removed leaving the lens with finished spherically curved opposite ends and an adaptability to modification by transaxial cutting and flat face finishing for plano-convex applications.

## Claims

### Claim 1

A method of making lenses comprising the steps of:
assembling a preform of glasses including a rod of lens glass and a surrounding cladding of leachable glass, said rod being of greater diametral size than desired of said lenses;
heating and drawing the preform to such a reduced cross-sectional size as to bring said rod to the diameter desired of said lenses;
cutting said drawn preform transaxially into a number of sections of lengths approximately equally the drawn preform diameter;
grinding said sections into spherical configurations of radii of curvature equalling that desired of at least one face of each of said lenses;
removing remaining leachable glasses from said sections whereby rod glasses each having at least one spherical face comprise said lenses; and
polishing said spherical faces of said lenses at a stage of said method following said grinding step.

### Claim 2 (depends on 1)

The method of claim 1 wherein said preform further includes a tube of glass outwardly of said leachable glass for use during said step of heating and drawing, said tube glass being removed during said grinding of said sections into said spherical configurations.

### Claim 3 (depends on 2)

The method according to claim 2 wherein said preform includes an additional glass intermediately of said rod of lens glass and leachable cladding, said additional glass being absorptive to light entering same and forming a permanent component of said lenses.

### Claim 4 (depends on 1)

The method according to claim 1 wherein said lenses have oppositely disposed convex faces and are cut intermediately of said convex faces into shorter lengths.

### Claim 5 (depends on 4)

The method according to claim 4 wherein faces resulting from said transaxial cutting are polished.

### Claim 6 (depends on 1)

The method according to claim 1 wherein said step of grinding said sections to spherical configurations includes a first operation of rough abrading to approximate spherical shape and a final operation of lapping to final spherical shape.

### Claim 7 (depends on 6)

The method according to claim 6 whereby said final operation is performed in a fashion similar to that used in the finishing of ball bearings.