Illumination and imaging subsystems for a lens inspection system

• US 5,528,357 A
• Filed: 02/13/1995
• Issued: 06/18/1996
• Est. Priority Date: 12/21/1992
• Status: Expired due to Term

• Current Assignee: Johnson & Johnson Vision Products, Inc.
• Original Assignee: Johnson & Johnson Vision Products, Inc.
• Inventors: Davis, Thomas G.
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/387,978
• Time in Patent Office: 491 Days
• Field of Search: 356/124-127, 356/237-239, 356/240, 356/430, 356/244, 356/246, 264/2.6, 250/562, 250/572, 250/223 B, 358/101, 358/106, 358/107, 382/8, 382/65, 351/211, 351/214
• US Class Current: 356/124
• CPC Class Codes: G01M 11/0214 Details of devices holding the object to be tested
• CPC Class Codes: G01M 11/0235 by measuring multiple properties of lenses, automatic lens meters
• CPC Class Codes: G01M 11/0278 Detecting defects of the object to be tested, e.g. scratches or dust investigating the presence of flaws or contamination on materials by optical means G01N21/88

Abstract

Illumination and imaging subsystems for a system for inspecting ophthalmic lenses. The subsystems include a lens holder, a light source, a pixel array and a processor. In use, the light source generates light pulses that are transmitted through the lenses in the lens holder and onto the pixel array to produce thereon light patterns representing the ophthalmic lenses. The pixel array generates signals representing the intensity of light thereon, and the processor processes those signals according to a predetermined program to generate an output signal representing a condition of the lens.

Claims

1. A lens inspection system for inspecting and detecting optical defects in ophthalmic lenses, comprising:

means for holding an ophthalmic lens which lens has a cross-sectional area;

lighting means for generating colliminated light pulses which colliminated light pulses have a cross-sectional area;

signal generating means to generate a set of signals representing the intensity of light incident thereon;

means for directing the light pulses through the lens holding means and onto said signal generating means to produce thereon a light pattern representing the ophthalmic lens held in the holding means wherein the means for directing the light pulses through the lens holding means is able to control the cross-sectional area of the light pulses such that the light pulses illuminate an area about 10% to about 15% larger than the cross-sectional area of the ophthalmic lens; and

processing means connected to the signal generating means to receive said set of signals therefrom, and to process said signals according to a predetermined program to generate an output signal representing at least one condition of the lens;

wherein the directing means includes

i) a stop axially disposed between the lens holding means and the signal generating means, and

ii) means for directing portions of the light pulses past the stop and onto the signal generating means to image thereon selected portions of the ophthalmic lens.

2. A lens inspection system according to claim 1, wherein the means for directing portions of the light pulses past the stop and onto the signal generating means includes an imaging lens disposed between the lens holding means and the stop to receive light transmitted through the ophthalmic lens, and to direct a portion of said transmitted light onto the stop and to direct another portion of said transmitted light onto the signal generating means.

3. A lens inspection system according to claim 1, wherein the means for directing portions of the light pulses past the stop and onto the signal generating means includes:

a first lens disposed on a first side of the lens holding means to direct the light pulses through the ophthalmic lens and to direct onto the stop a portion of the light directed through the ophthalmic lens; and

a second lens disposed on a second side of the lens holding means and between the stop and the signal generating means to receive and to direct onto the signal generating means another portion of the light directed through the ophthalmic lens.

4. A lens inspection system according to claim 1, wherein the means for directing portions of the light pulses past the stop and onto the signal generating means includes:

a first lens disposed between the lens holding means and the stop for receiving light transmitted through the ophthalmic lens, for directing a portion of said transmitted light onto the stop and for directing another portion of said transmitted light past the stop; and

a second lens disposed between the stop and the signal generating means for receiving said another portion of said transmitted light and directing said another portion of said transmitted light onto the signal generating means.

5. A lens inspection system according to claim 1, wherein the means for directing light pulses through the lens holding means includes:

a first mirror for receiving the light pulses from the lighting means and for directing the light pulses onto a given path through the lens holding means; and

means movably supporting the first mirror to adjust the direction at which the light pulses are directed through the lens holding means.

6. A lens inspection system according to claim 5, wherein the means for directing light pulses through the lens holding means further includes:

a second mirror for receiving the light pulses from the lighting means and for directing the light pulses onto the first mirror; and

an adjustable diaphragm located between the first and second mirrors to control the size of the cross-sectional area of the light pulses directed from the second mirror and onto the first mirror.

7. A lens inspection system according to claim 5, wherein the means for directing light pulses through the lens holding means further includes means movably supporting the lighting means to adjust the direction at which the light pulses are transmitted from the lighting means.

8. A lens inspection system according to claim 5, wherein:

the means for directing light pulses through the lens holding means includes a housing;

the lighting means and the first mirror are disposed in the housing;

the housing includes

i) a surface forming an opening located directly below the lens holding means, and

ii) a window disposed in said opening;

the first mirror directs the light pulses through the window and through the lens holding means; and

the housing further includes a seal extending around the window and said housing surface to inhibit fluids

from the lens holding means from entering the housing through the interface between the window and said housing surface.

9. A lens inspection system according to claim 1, wherein:

the signal generating means includes a housing and an array of pixels disposed in the housing; and

the means for directing light pulses through the lens holding means directs the light pulses through the lens holding means and into said housing, and includes

i) a first lens to focus said light pulses on a given plane in said housing, and

ii) a stop mounted in the housing on said given plane to block the light pulses focused thereon from the array of pixels.

10. A lens inspection system according to claim 9, wherein:

the first lens focuses a first portion of said light pulses onto said stop, and said stop blocks said first portion of said light pulses from the array of pixels;

the first lens directs a second portion of said light pulses past said stop and onto a second lens which images the second portion of said light onto the array of pixels; and

the set of signals generated by the signal generating means represent the intensity of the second portion of the light pulses incident on the pixel array.

11. A lens inspection system according to claim 9, wherein the first lens has front and back focal planes and a focal length, and wherein:

said given plane is located approximately at the back focal plane of the first lens;

the ophthalmic lens is disposed at approximately the front focal plane of the first lens; and

the second lens is separated from the first lens by approximately the focal length of the first lens.

12. A lens inspection system according to claim 1 wherein the at least one condition of the lens is a condition selected from the group consisting of an edge defect, an interior defect and decentration.

13. A lens inspection system for inspecting and detecting optical defects in ophthalmic lenses, comprising:

means for holding an ophthalmic lens having a preset diameter;

lighting means for generating colliminated light pulses;

signal generating means to generate a set of signals representing the intensity of light incident thereon;

means for directing the light pulses through the lens holding means through the lens holding means along a given path and onto said signal generating means to produce thereon a light pattern representing the ophthalmic lens held in the holding means comprising an adjustable diaphragm located on said given path to control the size of the cross-sectional area of the light pulses wherein the diaphragm limits the cross-sectional area of the light pulses so that the light pulses illuminate a circular area about 10% to 15% larger than said preset diameter, and including

i) a mirror for receiving the light pulses from the lighting means and for directing the light pulses onto a given path through the lens holding means,

ii) a stop axially disposed between the lens holding means and the signal generating means, and

iii) means for directing portions of the light pulses past the stop and onto the signal generating means to image thereon selected portions of the ophthalmic lens; and

processing means connected to the signal generating means to receive said set of signals therefrom, and to process said signals according to a predetermined program to generate an output signal representing at least one condition of the lens.

14. A lens inspection system according to claim 13, wherein:

the signal generating means includes a housing and an array of pixels; and

the means for directing portions of the light pulses past the stop and onto the signal generating means includes

i) a first lens disposed between the lens holding means and the stop for receiving light transmitted through the ophthalmic lens, for directing a portion of said transmitted light onto the stop and for directing another portion of said transmitted light past the stop, and

ii) a second lens disposed between the stop and the pixel array for receiving said another portion of said transmitted light and directing said another portion of said transmitted light onto the pixel array.

15. A lens inspection system according to claim 14, wherein the second lens has front and back focal planes and a focal length, and wherein:

the pixel array is located approximately at the back focal plane of the second lens;

the ophthalmic lens is disposed at approximately the front focal plane of the second lens; and

the first lens is separated from the second lens by approximately the focal length of the second lens.

16. A lens inspection system according to claim 13, wherein:

the signal generating means includes a housing and an array of pixels disposed in the housing; and

the means for directing portions of the light pulses past the stop and onto the signal generating means includes

i) a first lens disposed on a first side of the lens holding means to direct the light pulses through the ophthalmic lens and to direct onto the stop a portion of the light directed through the ophthalmic lens, and

ii) a second lens disposed on a second side of the lens holding means and between the stop and the pixel array to receive and to direct onto the pixel array another portion of the light directed through the ophthalmic lens.