Method for re-grinding and polishing free-form surfaces, especially rotationally symmetrical aspherical optical lenses

Abstract

A method for re-grinding and polishing free-form surfaces, especially rotationally symmetrical aspherical optical lenses by tools. in which the virtual levelling of a coarsely pre-grinded lens, for example, is calculated by interferometric measurement and by calculation with a desired form; pressure, rotational speed and sojourn time of the tools are controlled by means of said virtual levelling and the surface of the lens, for example, is divided up into partial areas. The partial areas correspond to the size of the tools. A zeroized approximation is calculated for the control of the tools. Said zeroized approximation enables the interaction of the partial areas to be estimated. By taking into account the estimated interaction, a sojourn time for each tool on each partial area is calculated as a function of pressure and rotational speed of the tool for each partial area, using a linear equation system and the tools are controlled accordingly. The invention also relates to tools and tool arrangements in addition to especially precise aspherical lenses.

1 - 37 . (canceled)  
   
   
       38 . A method for grinding and polishing free-form surfaces using at least one tool, the method comprising: 
 calculating a virtual removal of a preprocessed optical surface having an initial shape sufficient to achieve a desired shape;    dividing the optical surface into a plurality of subareas;    calculating a zeroth order approximation for estimating a mutual interaction for each adjacent subarea of the plurality of subareas;    calculating a dwell time of the at least one tool for each of the plurality of subareas using a linear system of equations, the calculating taking into account the respective mutual interaction and at least one of a contact pressure, a speed of rotation, and a behavior of a polishing agent of the at least one tool; and    controlling each of the at least one tool for each subarea so as to remove material from the optical surface in accordance with the virtual removal, wherein the controlling of the tool is performed by controlling at least one of the contact pressure, the speed of rotation, the dwell time, and a movement of the at least one tool.    
   
   
       39 . The method as recited in  claim 38 , wherein the preprocessed optical surface includes a rotationally symmetric aspherical optical surface.  
   
   
       40 . The method as recited in  claim 39 , wherein the rotationally symmetric aspherical optical surface includes at least one of a lens and a mirror.  
   
   
       41 . The method as recited in  claim 38 , wherein the preprocessed optical surface is pre-grinded.  
   
   
       42 . The method as recited in  claim 38 , wherein the calculating of the virtual removal is performed using interferometrical measurement and comparison of the initial shape to the desired shape.  
   
   
       43 . The method as recited in  claim 38 , wherein a size of each of the plurality of subareas corresponds to a size of the at least one tool.  
   
   
       44 . The method as recited in  claim 38 , wherein a size of each of the plurality of subareas corresponds to double a size of the at least one tool.  
   
   
       45 . The method as recited in  claim 38 , wherein the controlling of the at least one tool is performed by varying the dwell time.  
   
   
       46 . The method as recited in  claim 38 , wherein the controlling of the at least one tool is performed by varying the speed of rotation.  
   
   
       47 . The method as recited in  claim 38 , wherein the controlling of the at least one tool is performed by varying a speed of rotation of the optical surface.  
   
   
       48 . The method as recited in  claim 38 , wherein the controlling of the at least one tool is performed by varying the contact pressure.  
   
   
       49 . The method as recited in  claim 38 , wherein the controlling of the tool is performed so as to remove only the minimally necessary material for a correction of the surface.  
   
   
       50 . The method as recited in  claim 39 , wherein the virtual removal is transferred to an one-dimensional form, and lens is rotating during the grinding and polishing.  
   
   
       51 . The method as recited in  claim 38 , wherein the controlling of the at least one tool is performed only once and a total processing time of less than about ten minutes.  
   
   
       52 . The method as recited in  claim 38 , further comprising controlling each of the at least one second tool after the controlling of each of the at least one tool, wherein each of the at least one second tool is smaller than each of the at least one tool.  
   
   
       53 . The method as recited in  claim 38 , wherein the plurality of subareas do not overlap with one another.  
   
   
       54 . The method as recited in  claim 38 , wherein the plurality of subareas overlap with one another.  
   
   
       55 . The method as recited in  claim 54 , wherein the plurality of subareas overlap substantially.  
   
   
       56 . The method as recited in  claim 38 , wherein the plurality of subareas exhibit different sizes.  
   
   
       57 . An aspherical glass lens having an accuracy better than 600 nanometers, grinded and polished within about 20 minutes according to the method recited in  claim 38 .  
   
   
       58 . An aspherical glass lens having an accuracy better than 600 nanometers and a concave surface, grinded and polished using a BestFit radius of curvature of less than 50 mm within a time of about 40 minutes according to the method recited in  claim 38 .  
   
   
       59 . A correction tool for the processing of rotationally symmetric free-form surfaces according to the method recited in  claim 38 , wherein the correction tool is rotatable and radially moveable, and wherein a ratio of the size of the tool and the diameter of free-form surface is between one eighth and one quarter.  
   
   
       60 . A tool for the processing of rotationally symmetric free-form surfaces according to the method as recited in  claim 38 , wherein the tool is rotatable and radially moveable, and wherein a size of the tool is twice as wide as the narrowest mountain of errors on the free-form surface to be removed.  
   
   
       61 . The correction tool as recited in  claim 59 , further comprising a polishing or grinding foil including a homogeneous material.  
   
   
       62 . The correction tool as recited in  claim 61 , wherein the homogeneous material is free of bubbles and indentations.  
   
   
       63 . The correction tool as recited in  claim 61 , wherein the tool includes a plurality of indentations from a working surface of the tool having steep edges with respect to the working surface, the indentations for supplying at least one of a polishing agent and a cooling agent.  
   
   
       64 . An arrangement comprising a plurality of the tools as recited in claim  19  for simultaneously processing a first surface of the free-form surface.  
   
   
       65 . The arrangement as recited in  claim 64 , wherein each of the plurality of tools is disposed perpendicularly with respect to the optical surface.  
   
   
       66 . The arrangement as recited in  claim 64 , wherein each of the plurality of tools moves on a radial line of a rotationally symmetric free-form surface.  
   
   
       67 . The arrangement as recited in  claim 64 , wherein each of the plurality of tools moves on a non-radial line of the free-form surface.  
   
   
       68 . The arrangement as recited in  claim 64 , wherein each of the plurality of tools does not move on the free-form surface.  
   
   
       69 . The arrangement as recited in  claim 64 , wherein each of the plurality of tools are arranged on the free-form surface in such a way that, in case of a rotating free-form surface, the entire free-form surface is processed.  
   
   
       70 . The arrangement as recited in  claim 64 , wherein the first surface amounts is more than five percent of the free-form surface.  
   
   
       71 . The arrangement as recited in  claim 64 , wherein the plurality of tools are controlled separately.  
   
   
       72 . The correction tool as recited in  claim 59  further comprising a movable foot at a processing side of the tool, wherein the foot orients itself such that the tool overlies the free-form surface tangentially.  
   
   
       73 . The arrangement as recited in  claim 64 , wherein the plurality of tools are available in compounds.  
   
   
       74 . The arrangement as recited in  claim 73 , wherein the compounds are rod-shaped.  
   
   
       75 . The arrangement as recited in  claim 73 , wherein the compounds are round.  
   
   
       76 . The arrangement as recited in  claim 73 , wherein the compounds are positioned across the free-form surface and moved as a single tool.  
   
   
       77 . The method as recited in  claim 38 , further comprising a subsequent polishing of the free-form surface, wherein the polishing preserves or improves an accuracy of the free-form surface.