Claims
- 1. An interferometer for providing data regarding the contour of aspheric surfaces; the interferometer comprising:
- a first off-axis parabolic reflective surface having a focal point;
- a source of light positioned at said focal point of said first parabolic reflective surface;
- a second off-axis parabolic reflective surface positioned for receiving collimated light from said first parabolic reflective, for directing said light onto one of said aspheric surfaces and for receiving light reflected from said one of said aspheric surfaces and directing said reflected light toward said first parabolic reflective surface;
- a beamsplitter positioned between said first and second parabolic reflective surfaces for re-directing a selected portion of light traveling therebetween in a direction substantially perpendicular thereto;
- a plano reference mirror positioned in spaced-apart relation to said beamsplitter along said perpendicular direction for reflecting said re-directed portion of light as a reference through said beamsplitter along said perpendicular direction;
- a third off-axis parabolic reflective surface positioned in spaced-apart relation to said beamsplitter along said perpendicular direction and opposite of said mirror for receiving said mirror-reflected light from said beamsplitter;
- said beamsplitter also redirecting said light reflected from said aspheric surface onto said third parabolic reflective surface for producing an interference fringe pattern representing the differences between said aspheric surface and a spherical reference surface.
- 2. The interferometer defined in claim 1 further comprising a detector; said detector being positioned relative to said third parabolic reflective surface for directing said interferometer fringe pattern onto said detector.
- 3. The interferometer defined in claim 1 further comprising a beamsplitter compensator plate positioned between said beamsplitter and said second parabolic reflective surface for equalizing beamsplitter-induced differences in path characteristics between said mirror-reflected light and said aspheric surface-reflect light.
- 4. The interferometer recited in claim 1 wherein the F-numbers of said second and third parabolic reflective surfaces are equal.
- 5. The interferometer recited in claim 1 wherein the F-numbers of said first, second and third parabolic reflective surfaces are each in the range of 0.6 to 20.0.
- 6. The interferometer recited in claim 1 wherein said source of light comprises at least one laser.
- 7. The interferometer recited in claim 1 wherein said source of light is a plurality of coaxial light beams, each such light beam being generated by a laser.
- 8. The interferometer recited in claim 1 wherein each of said light beams has a wavelength that is different from the other of said light beams.
- 9. The interferometer recited in claim 1 wherein said aspheric surface is a human cornea.
- 10. An interferometer of the type employing interference patterns between test and reference wavefronts for mapping the contour of a human cornea; said interferometer comprising:
- a light source generating light simultaneously having two discrete wavelengths;
- optical train means for receiving said light and preserving, without any substantial error, the optical path difference between said test and reference wavefronts at both of said wavelengths; and
- means for detecting the difference in interference patterns generated at each of said wavelengths;
- said optical train means having a pair of off-axis parabolic reflecting surfaces having equal F-numbers.
ORIGIN OF INVENTION
The invention described herein was made in the performance of work under NASA contract No. NAS-7-918, and is subject to the provisions of Public Law 96-517 (35 USC 202) in which the Contractor has elected to retain title.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4810093 |
Doyle |
Mar 1989 |
|
4832489 |
Wyant et al. |
May 1989 |
|