Automated lensometer

• US 5,331,394 A
• Filed: 04/10/1992
• Issued: 07/19/1994
• Est. Priority Date: 04/10/1992
• Status: Expired due to Fees

• Current Assignee: Alcon Manufacturing Limited (Alcon Incorporated)
• Original Assignee: Metaphase Corporation
• Inventors: Shalon, Tadmor, Pund, Marvin L.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US07/867,313
• Time in Patent Office: 830 Days
• Field of Search: 356/124, 356/125, 356/126, 356/127
• US Class Current: 356/124
• CPC Class Codes: G01M 11/0235 by measuring multiple properties of lenses, automatic lens meters

Abstract

An automated lensometer including a mounting device to support and center a lens to be tested along an axis. First and second arrays of light source patterns are positioned at different optical distances from the mounted lens and are projected along the axis through the lens. The images of the projected patterns are captured and stored in a camera imaging device located along the axis. A comparison of the patterns by a processor allows derivation of refractive power of the lens.

Claims

1. A lensometer for measuring refractive power parameters of an eyeglass or contact lens including spherical refractive power, cylindrical refractive power, and prism power, comprising:

means for holding the lens in a fixed position relative to an axis;

means for projecting a pattern of light sources generally along the axis through the lens from a first distance relative to the lens, and through the lens from a second distance relative to the lens;

means for capturing images of the pattern of lights projected from the first and second distances; and

means for analyzing the images and deriving the refractive parameters from a comparison of the images.

2. The lensometer of claim 1 further comprising a frame means including a base, an extension connected to the base, means for holding the lens, and a camera means.

3. The lensometer of claim 1 wherein the means for holding the lens includes releasable means for releasably holding the lens.

4. The lensometer of claim 1 wherein the means for projecting includes an array of light sources arranged in a geometric pattern.

5. The lensometer of claim 4 further comprising first and second arrays of light sources.

6. The lensometer of claim 5 wherein the projected light sources are associated with a beam splitter which projects the sources along a common axis but where the distance of travel of each array of light sources differs a known distance.

7. The lensometer of claim 1 wherein the means for capturing the images includes a camera means.

8. The lensometer of claim 7 wherein the camera means includes a lens, a telecentric aperture stop, and a CCD means.

9. The lensometer of claim 1 wherein the means for analyzing the images comprises an image processing means and a processor means.

10. The lensometer of claim 1 further comprising a support means which is translatable with respect to the means for holding.

11. The lensometer of claim 1 further comprising a marker means which is translatable with regard to the means for holding to impose a mark on the lens.

12. The lensometer of claim 1 further comprising a display means for displaying the refractive power parameters obtained by the lensometer.

13. The lensometer of claim 1 further comprising a power source to provide electrical power to the lensometer.

14. The lensometer of claim 1 further comprising a housing means to fix the means for holding the lens a known distance from the means for projecting a pattern of lights, and to align the means for projecting a pattern of lights, the means for holding lens, and the means for capturing the images generally along an axis.

15. An automated lensometer for the measurement of properties of optical lenses for glasses and contacts comprising:

a base means for positioning the lensometer means on a surface;

an upwardly extending arm means connected to the base means;

a camera means mounted to the arm means;

a projector means mounted to the arm means between the base means and the camera means;

a lens holding means associated with the arm means and located between the projector means and camera means, which are aligned along an axis;

the lens holding means releasably holding the lens along the axis;

the projector means including first and second arrays of light source means, each light source means located a fixed but different distance from a lens held in the lens holding means; and

processor means for measuring properties of the lens from differences in images from the light source means.

16. The lensometer of claim 15 wherein the base means includes a bottom side with support portions capable of placement of the base on a surface comprising a table top.

17. The lensometer of claim 15 wherein the base includes a control panel means and display means.

18. The lensometer of claim 15 wherein the arm means extends no more than approximately three feet vertically.

19. The lensometer of claim 15 wherein the arm means includes adjustment means for adjusting the relationship between the projector means, the camera means, and the base means.

20. The lensometer of claim 15 wherein the camera means includes a lens, telecentric aperture stop, and an imaging CCD means.

21. The lensometer of claim 15 wherein the projector means includes multiple light sources, pin holes, and an optic system to project multiple light sources along the axis.

22. The lensometer of claim 21 wherein the optic system includes one or more beam splitters.

23. The lensometer of claim 15 wherein the lens holding means is translatable with respect to the projector means.

24. The lensometer of claim 15 wherein the processor means includes a storage means, a discerning means for determining the center of mass of each captured light source;

a calculating means to calculate the geometric center of the captured array of light sources; and

a comparing means for comparing the arrays captured by camera means.

25. The lensometer of claim 15 wherein the processor means includes a storage means, means to determine the optical center of the lens, means to indicate the direction to move the lens to reach its optical center along the axis.

26. A method of measuring optical properties of eyeglass and contact lenses comprising:

positioning a lens along an axis;

positioning the optical center of the lens along the axis;

projecting a geometric pattern of light sources through the lens along the axle;

capturing the geometric pattern and recording the pattern;

determining the geometric center of each light source and the relationship of each geometric center to one another;

storing that information in a storage means;

projecting a second pattern of light sources through lens, but along a different and longer optical path from the first projected array of light sources;

capturing the second projected geometric pattern of light sources;

determining the geometric center of each light source and with respect to one another;

storing that information in a storage means;

comparing the stored information of both projected geometric patterns, calculating the distance between geometric centers of corresponding light spots; and

computing the optical properties of the lens from the comparison.