US3889431A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making schmidt corrector lenses
Assignee: CELESTRON PACIFIC
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Filing: 1974-09-23
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Granted: 1975-06-17
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Expires: 1994-09-23
Abstract
Abstract A method and system for making Schmidt correctors wherein the surface of a master glass template is ground and polished to an accurate inverse curve of a corrector plate, a thin glass workpiece is placed under vacuum on the master glass template in intimate curve conformed glass-to-glass contact over the entire mating surfaces, the template and workpiece being conjointly rotated while grinding and polishing the exposed free surface of the workpiece to a uniform accurate flatness whereafter the vacuum is released and the workpiece is removed from the template in final form. The present method is directed to inverting the workpiece during polishing and grind, so as to overcome irregularities in the workpiece itself.
Inventors
- 👤 Thomas J Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:44
CPC Classifications
B; B24; B24B; B24B13/00; B24B13/0043
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
190 words
A method for forming a master glass template used in making Schmidt correctors, comprising: A. cutting a thin test piece of glass so as to form shallow grooves in the surface thereof in a cartwheel pattern; B. mounting said test piece upon a previously ground master glass template contour block having a bore therethrough and being mounted upon a grinding machine backing plate having a hollow spindle through which a vacuum may be drawn, such that the test piece grooves interface with said glass template block and intersect said bore; C. drawing a vacuum through said grooves and between said block and test piece, so as to deform the test piece to the curve on the contour block as previously ground, vacuum forming an intimate glass-to-glass contact between block and test piece; D. grinding the exposed surface of the test piece to a uniform accurate flatness; E. removing and testing the test piece for accuracy of the desired inverse curve of the block; F. marking excess glass on said test piece; and G. further grinding and polishing said testpiece so as to remove residual errors in the contour surface thereof.
Claim 2
Independent Claim
190 words
A method for forming a master glass template used in making Schmidt correctors, comprising: A. cutting a thin test piece of glass so as to form shallow grooves in the surface thereof in a cartwheel pattern; B. mounting said test piece upon a previously ground master glass template contour block having a bore therethrough and being mounted upon a grinding machine backing plate having a hollow spindle through which a vacuum may be drawn, such that the test piece grooves interface with said glass template block and intersect said bore; C. drawing a vacuum through said grooves and between said block and test piece, so as to deform the test piece to the curve on the contour block as previously ground, vacuum forming an intimate glass-to-glass contact between block and test piece; D. grinding the exposed surface of the test piece to a uniform accurate flatness; E. removing and testing the test piece for accuracy of the desired inverse curve of the block; F. marking excess glass on said test piece; and G. further grinding and polishing said testpiece so as to remove residual errors in the contour surface thereof.
Claim 3
Dependent Claim
44 words
A method of making Schmidt correctors as in claim 1, wherein said testpiece is removed from the master and reversed contacted with the master such that the side of the testpiece which was previously in contact with the master is around and polished flat.
Claim 4
Dependent Claim
68 words
A method of making Schmidt correctors as in claim 1, including initially grinding said testpiece upon a master contour block having a reduced figure of accuracy than that desired to achieve the final Schmidt corrector accuracy, then reverse contacting said testpiece to a master contour block having the desired accuracy of figure and grinding the top surface of the testpiece and polishing while in contact with contour block.
Claim 5
Dependent Claim
44 words
Method of making Schmidt correctors as in claim 1, including Grinding of said testpiece exposed side to a spherical surface and testing deviation from flatness, so as to shift the neutral zone of the Schmidt corrector to a smaller or larger radius as desired.
Claim 6
Dependent Claim
129 words
Method of forming Schmidt correctors as in claim 1, including F. producing a thick Schmidt corrector lense, having the same oversized diameter as the master contour block such that said corrector lense is figured flat on one side and has all of the Schmidt curve on its opposite side, G. subsequently grinding in the cartwheel pattern which is to serve as vacuum or compressed air grooves, such that the Schmidt corrector lense serves as a master contour block. H. marking deviations in the curve of the master contour block by the interference fringes between the thick Schmidt corrector lense used as a template and the contour block under preparation; and I. introducing compressed air into the cartwheel pattern, so as to remove the Schmidt corrector from the contour block.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |