Method for making replica contour block masters for producing Schmidt corrector plates

Abstract

A method for making replica contour block masters for use in producing Schmidt correctors wherein a finished Schmidt corrector plate to be duplicated, which is flat on one side and figured on the other, is placed with its flat side on a flat surfaced spindle master, a thin piece of glass to constitute a replica piece is placed on the corrector plate and a vacuum drawn therebetween to conform their surfaces, the replica piece is ground and polished flat on the free surface, the corrector plate and replica piece removed from the spindle master and the replica piece placed flat side to flat surface on the spindle master in a semipermanent bond therewith and constituting together a contour block master.

We claim: 
     
       1. A method for making replica contour block masters for use in producing Schmidt correctors comprising: A. mounting a corrector plate to be duplicated, having a flat side and a contoured side, on a flat surfaced spindle master in flat side to flat surfaced contact;   B. mounting a flat surfaced piece of glass to constitute a replica piece on the corrector plate;   C. introducing a vacuum between said corrector plate and said replica piece to conform mating surfaces thereof;   D. grinding and polishing the upper free surface of said replica piece flat;   E. releasing the vacuum; and   F. removing said corrector plate and replica piece from said spindle master, the replica piece being corresponded in contour on one side to said corrector plate, and constituting a component for use as a contour block master.   
     
     
       2. A method as claimed in claim 1, wherein said replica piece is contoured on one side and flat on the other side thereof, and mounting said replica piece with the flat side thereof juxtaposed to the flat surface of said spindle master in a semi-permanent bond therewith and consituting together a finalized contour block master. 
     
     
       3. A method as claimed in claim 2, including accurately determining and marking the optical center of said corrector plate, grinding a small hole into said center and grooving said corrector plate on the contoured side thereof in a cartwheel pattern, said vacuum being introduced through said hole and thereby into said grooves to facilitate conforming mating surfaces of said corrector plate and said replica piece. 
     
     
       4. A method as claimed in claim 3, wherein the exact optical center of said corrector plate is placed over the center of rotation of said spindle master and said corrector plate and spindle master are indexed for subsequent return, after removal, to the exact same position and orientation and so that said replica piece can be mounted on said spindle master to constitute said contour block master in the same orientation. 
     
     
       5. A method as claimed in claim 4, wherein, subsequent to removal of said corrector plate and replica piece from said spindle master, said replica piece is cored in the center prior to mounting flat side to flat surface on said spindle master in the exact orientation as when said replica piece is ground and polished and said replica piece is replaced in the exact orientation as when ground on said spindle master to eliminate any irregularities present on said spindle master. 
     
     
       6. A method as claimed in claim 5, wherein, subsequent to mounting of said replica piece on said spindle master, the top contoured surface of said replica piece is grooved in a cartwheel pattern. 
     
     
       7. A method as claimed in claim 6, wherein said replica piece is in a semi-permanent bond with said spindle master and held in place by optical contact only. .Iadd. 8. In a contour block master for use in producing Schmidt correctors the combination of: A. a thick master which is flat on one side, and   B. a thin piece which is flat on one side and having its other side ground and polished to the inverse curve of the desired Schmidt corrector, said thin piece being mounted on the thick contour block master flat side to flat side in a semi-permanent bond, the combination serving the same   
     
     
        purpose as a solid contour block master. .Iaddend..Iadd. 9.  In a contour block master for use in producing Schmidt correctors the combination of claim 8, wherein said thin piece has a small hole ground into its center with shallow grooves on the curve side extending in a cartwheel pattern from said small hole. .Iaddend..Iadd. 10. The product of a replica piece by the process of claim 1. .Iaddend..Iadd. 11. The product of a two-piece contour block master by the process of claim 2. .Iaddend..Iadd. 12. The product of a two-piece contour block master by the process of claim 3. .Iaddend. .Iadd. 13. The product of a two-piece contour block master by the process of claim 4. .Iaddend..Iadd. 14. The product of a two-piece contour block master by the process of claim 5. .Iaddend..Iadd. 15. The product of a two-piece contour block master by the process of claim 6. .Iaddend..Iadd. 16. The product of a two-piece contour block master by the process of claim 7. .Iaddend. .Iadd. 17. A method for making replica contour block masters for use in producing Schmidt correctors comprising: A. mounting a corrector plate to be duplicated having a flat side and a contoured side on a vacuum device;   B. mounting a flat surface piece of glass to constitute a replica piece on the corrector plate on a contoured side thereof;   C. introducing a vacuum between said corrector plate and said replica piece to conform the mating surfaces thereof;   D. grinding and polishing the upper free surface of said replica piece flat;   E. releasing the vacuum; and   F. separating said corrector plate and replica piece, the replica piece being corresponded in contour on one side to said corrector plate, and constituting a component for use as a contour block master. .Iaddend.