Open lattice mirror structure and method of manufacturing same

Abstract

An open lattice mirror structure with an optical face sheet, a supporting isogrid framework supporting the optical face sheet, an isogrid back plane, and a truss core interconnecting the supporting isogrid framework and the isogrid back plane for transferring shear loads evenly between the face sheet and the isogrid back plane. Also disclosed are methods of making such a structure and a method of polishing the optical face sheet to prevent quilting.

What is claimed is:  
     
         1 . An open lattice mirror structure comprising: 
 an optical face sheet;    a supporting isogrid framework supporting the optical face sheet;    an isogrid back plane; and    a truss core interconnecting the supporting isogrid framework and the isogrid back plane for transferring shear loads evenly between the face sheet and the isogrid back plane.    
     
     
         2 . The open lattice mirror structure of  claim 1  in which the supporting isogrid framework, the isogrid back plane, and the truss core are formed from composite members.  
     
     
         3 . The open lattice mirror structure of  claim 2  in which the composite members include lengthy fibers.  
     
     
         4 . The open lattice mirror structure of  claim 3  in which the fibers are made carbon.  
     
     
         5 . The open lattice mirror structure of  claim 3  in which said fibers are arranged in bundles in a resin matrix.  
     
     
         6 . The open lattice mirror structure of  claim 5  in which said fibers are arranged in an array to produce flat members.  
     
     
         7 . The open lattice mirror structure of  claim 3  in which said fibers are disposed in layers consolidated together.  
     
     
         8 . The open lattice mirror structure of  claim 1  in which said core includes members extending at an angle from the back plane to the supporting framework.  
     
     
         9 . The open lattice mirror structure of  claim 1  in which said core includes members extending perpendicularly between the back plane and the supporting framework.  
     
     
         10 . The open lattice mirror structure of  claim 1  in which the supporting isogrid framework includes six sides and spaced members extending between the sides intersecting to form isosceles triangles.  
     
     
         11 . The open lattice mirror structure of  claim 1  in which the isogrid back plane includes six sides and spaced members extending between the sides intersecting to form isosceles triangles.  
     
     
         12 . The open lattice mirror structure of  claim 1  in which the optical face sheet forms a convex, concave, or planar mirror.  
     
     
         13 . A method of making a mirror structure, the method comprising: 
 assembling a supporting isogrid framework;    assembling an isogrid back plane;    interconnecting the supporting isogrid framework with the isogrid back plane by a truss core; and    disposing an optical surface on the supporting isogrid framework.    
     
     
         14 . The method of  claim 13  in which the supporting isogrid framework, the isogrid back plane, and the truss core are formed from composite members.  
     
     
         15 . The method of  claim 14  in which the composite members are made of lengthy fibers in a resin matrix.  
     
     
         16 . The method of  claim 14  in which the fibers are made of carbon.  
     
     
         17 . The method of  claim 11  in which the fibers are bundled.  
     
     
         18 . The method of  claim 13  in which interconnecting includes disposing members at an angle between the back plane and the supporting framework.  
     
     
         19 . The method of  claim 13  in which interconnecting includes disposing members perpendicularly between the back plane and the supporting framework.  
     
     
         20 . The method of  claim 13  in which the supporting isogrid framework includes six sides and spaced members extending between the sides intersecting to form isosceles triangles.  
     
     
         21 . The method of  claim 13  in which the isogrid back plane includes six sides and spaced members extending between the sides intersecting to form isosceles triangles.  
     
     
         22 . The method of  claim 13  in which the optical face sheet forms a convex, concave, or planar mirror.  
     
     
         23 . The method of  claim 13  further including polishing the optical surface.  
     
     
         24 . The method of  claim 23  in which polishing includes filling the truss core with a removable substance, grinding the optical surface, and removing the removable substance.  
     
     
         25 . The method of  claim 24  in which the removable substance includes particles.  
     
     
         26 . The method of  claim 25  in which the particles are selected from glass, fused silica, sand, and granite material.  
     
     
         27 . The method of  claim 26  in which the particles are mixed with a binder material.  
     
     
         28 . The method of  claim 27  in which the binder material is selected from waxes, gypsum, epoxies, and adhesives.  
     
     
         29 . The method of  claim 24  in which the optical surface is turned upside down, the removable substance is poured into the truss core through the isogrid back plane, and cured.  
     
     
         30 . The method of  claim 24  in which the removable substance is removed by a technique selected from melting, dissolving, degaussing, and vibration techniques.  
     
     
         31 . The method of  claim 30  further including the step of fiquring the optical surface after the substance is removed.  
     
     
         32 . A method of polishing an optical surface supported by a back structure, the method comprising: 
 filling the back structure with a removable substance;    grinding the optical surface; and    removing the removable substance.    
     
     
         33 . The method of  claim 32  in which the back structure has an open lattice configuration.  
     
     
         34 . The method of  claim 32  in which the removable substance includes particles.  
     
     
         35 . The method of  claim 34  in which the particles are selected from glass, fused silica, sand, and granite material.  
     
     
         36 . The method of  claim 34  in which the particles are mixed with a binder material.  
     
     
         37 . The method of  claim 36  in which the binder material is selected from waxes, gypsum, epoxies, and adhesives.  
     
     
         38 . The method of  claim 32  in which the optical surface is turned upside down, the substance is poured into the back structure, and cured.  
     
     
         39 . The method of  claim 32  in which the removable substance is removed by a technique selected from melting, dissolving, degaussing, and vibration techniques.  
     
     
         40 . The method of  claim 32  further including the step of fiquring the optical surface after the substance is removed.  
     
     
         41 . An open lattice optical back structure comprising: 
 an optical face sheet;    a back plane; and    a truss core between the back plane and the optical face sheet for transferring shear loads to the back plane.    
     
     
         42 . The back structure of  claim 41  further including a supporting isogrid structure between the optical face sheet and the truss core.  
     
     
         43 . The back structure of  claim 41  in which the back plane is an isogrid structure.  
     
     
         44 . An open lattice optical back structure comprising: 
 a supporting isogrid framework supporting an optical face sheet;    a back plane; and    a core interconnecting the supporting isogrid framework and the back plane for transferring shear loads to the isogrid back plane.    
     
     
         45 . The back structure of  claim 44  in which the core is a truss structure.  
     
     
         46 . The back structure of  claim 44  in which the back plane is an isogrid structure.  
     
     
         47 . An open lattice optical back structure comprising: 
 an optical face sheet;    an isogrid back plane; and    a core between the optical face sheet and the isogrid back plane for transferring shear loads to the isogrid back plane.    
     
     
         48 . The back structure of  claim 47  further including an isogrid framework supporting structure between the core and the optical face sheet.  
     
     
         49 . The back structure of  claim 47  in which the core is a truss core.  
     
     
         50 . An open lattice optical back structure comprising: 
 a supporting isogrid framework which supports an optical face sheet;    an isogrid back plane; and    a core interconnecting the supporting isogrid framework and the isogrid back plane for transferring shear loads to the isogrid back plane.    
     
     
         51 . The back structure of  claim 50  in which the core is a truss core structure.