US3769762A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for controlled lapping of optical surfaces to correct deviations from desired contours
Assignee: ALTAIR SCIENT Inc
•
Filing: 1972-03-07
•
Granted: 1973-11-06
•
Expires: 1992-03-07
Abstract
Abstract Apparatus for scanning an aspheric optical surface in a spiral pattern and lapping with short strokes is provided by rotating a table supporting the workpiece at a controlled rate, radially moving an arm carriage, and cyclically driving the arm on the carriage with a crank to produce short lapping strokes along the spiral scanning path. A program prepared from contour deviation plots along several diameters of the workpiece (made by knifeedge measurement techniques) control the rate of rotation of the workpiece inversely proportional to deviations from the desired surface contour. After repeated use of one program has reduced deviations by at least half, measurements are again made and a new program is prepared. Each iteration of a given program is run at a rate which assures completion of the entire program in an interval of time during which the rate of material removal will not vary by more than 10 percent.
Inventors
- 👤 M Mayo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:29
CPC Classifications
B; B24; B24B; B24B13/00; B24B13/06
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
221 words
A method of polishing the optical surface of a workpiece to conform to a desired contour within specified tolerances using apparatus for removing material at successive points over the entire optical surface of said workpiece in response to a predetermined and programmed pattern comprising the steps of establishing a time interval during which the rate of material removal from said optical surface does not vary more than a small percentage for current lapping conditions, measuRing the deviation of each point of said optical surface from said desired contour, preparing a program for said apparatus to complete one cycle of material removal over all points of said optical surface within a period equal to said interval such that, for each point on said optical surface, the material removed is proportional to said measured deviation from said desired contour, removing material from the entire surface of said workpiece during one cycle of material removal over all points according to said program, repeating said one cycle of material removal over all points according to said program until a significant and measurable amount of material is removed from all points of said optical surface, but only a fraction of said deviation has been corrected, and repeating the entire process until all points of said optical surface conform to said desired contour within said specified tolerance.
Claim 2
Independent Claim
221 words
A method of polishing the optical surface of a workpiece to conform to a desired contour within specified tolerances using apparatus for removing material at successive points over the entire optical surface of said workpiece in response to a predetermined and programmed pattern comprising the steps of establishing a time interval during which the rate of material removal from said optical surface does not vary more than a small percentage for current lapping conditions, measuRing the deviation of each point of said optical surface from said desired contour, preparing a program for said apparatus to complete one cycle of material removal over all points of said optical surface within a period equal to said interval such that, for each point on said optical surface, the material removed is proportional to said measured deviation from said desired contour, removing material from the entire surface of said workpiece during one cycle of material removal over all points according to said program, repeating said one cycle of material removal over all points according to said program until a significant and measurable amount of material is removed from all points of said optical surface, but only a fraction of said deviation has been corrected, and repeating the entire process until all points of said optical surface conform to said desired contour within said specified tolerance.
Claim 3
Independent Claim
201 words
A method of polishing an optical surface to a desired contour within specified tolerances using apparatus for lapping said surface with a pad using small strokes while scanning all of said surface in a predetermined pattern comprising the steps of establishing a time interval during which the rate of material removal by said lapping strokes can be expected to remain constant within a small percentage for current operating conditions, measuring the deviation of said surface from said desired contour, preparing a program to control lapping of the entire optical surface in one cycle and in a period of time equal to or less than said time interval such that for each point the total time during which said pad is in contact is proportional to said deviation from said contour, lapping said surface under control of said program while scanning all of said surface in one cycle, repeating the step of lapping said surface under control of said program in one scanning cycle until a significant and measurable amount of material is removed from all points of said optical surface, and repeating the entire process until all points of said optical surface conform to said desired contour within said specified tolerance.
Claim 4
Independent Claim
201 words
A method of polishing an optical surface to a desired contour within specified tolerances using apparatus for lapping said surface with a pad using small strokes while scanning all of said surface in a predetermined pattern comprising the steps of establishing a time interval during which the rate of material removal by said lapping strokes can be expected to remain constant within a small percentage for current operating conditions, measuring the deviation of said surface from said desired contour, preparing a program to control lapping of the entire optical surface in one cycle and in a period of time equal to or less than said time interval such that for each point the total time during which said pad is in contact is proportional to said deviation from said contour, lapping said surface under control of said program while scanning all of said surface in one cycle, repeating the step of lapping said surface under control of said program in one scanning cycle until a significant and measurable amount of material is removed from all points of said optical surface, and repeating the entire process until all points of said optical surface conform to said desired contour within said specified tolerance.
Claim 5
Dependent Claim
60 words
A method as defined in claim 2 wherein said program is prepared to cover said optical surface along a predetermined scanning pattern at a controlled rate with small lapping strokes at a substantially constant pressure superimposed on the scanning pattern at a controlled rate, and to vary a selected one of said controlled rates as a function of said deviation.
Claim 6
Dependent Claim
18 words
A method as defined in claim 3 wherein the rate varied is the rate of said scanning pattern.
References Cited (Backward Citations)
US1089456A
Cited
US1973527A
Cited
US2310925A
Cited
US2319922A
Cited
US3156073A
Cited
US3427751A
Cited
US3564776A
Cited
US3670460A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |