Generation of aspheric surfaces

Claim 1

APPARATUS FOR PRODUCING ON A WORKPIECE BY MEANS OF A TOOL AN ASPHERIC SURFACE OF REVOLUTION WHICH DEVIATES FROM A BASIC SPHERICAL SURFACE BY RELATIVELY SMALL AMOUNTS AT DIFFERENT RADIAL DISTANCES FROM THE AXIS OF SYMMETRY, SAID APPARATUS COMPRISING A FIXED BASE, A WORKHOLDER FOR CARRYING THE WORKPIECE, MEANS FOR ROTATING THE WORKHOLDER ABOUT AN AXIS CONSTITUTING THE SAID AXIS OF SYMMETRY, A TOOL HOLDER FOR CARRYING THE TOOL IN OPERATIVE RELATIONSHIP TO THE WORKPIECE ON THE WORKHOLDER, A PIVOT ELEMENT MOUNTING MEANS ON THE BASE FOR LOCATING THE WORKHOLDER AND THE TOOLHOLDER RELATIVELY TO THE PIVOT ELEMENT WHEREBY THE AXIS OF SUCH PIVOT INTERSECTS THE AXIS OF ROTATION OF THE WORKHOLDER AT RIGHT ANGLES AT A POINT CONSTITUTING THE CENTER OF THE SAID BASIC SPHERICAL SURFACE, MEANS FOR APPLYING TO THE WORKHOLDER AND THE TOOLHOLDER A RELATIVE ROTATIONAL TRAVERSING MOVEMENT ABOUT THE FIXED PIVOT AXIS, AN OPTICAL CAM DEVICE CONSISTING OF A SHEET BEARING A CURVED LINE WHICH CONTRASTS IN RESPECT OF LIGHTTRANSMITTING PROPERTIES WITH THE BACKGROUND CONSTITUTED BY THE ADJACENT PORTIONS OF THE SHEET AND HAS A SHAPE DEPENDENT UPON THE DEVIATIONS OF THE DESIRED ASPHERIC SURFACE FROM THE BASIC SPHERICAL SURFACE, AN OPTICAL UNIT COOPERATING WITH THE OPTICAL CAM DEVICE, MEANS CONTROLLED IN ACCORDANCE WITH THE RELATIVE ROTATIONAL TRAVERSING MOVEMENT BETWEEN THE WORKHOLDER AND THE TOOLHOLDER FOR EFFECTING A RELATIVE TRAVERSING MOVEMENT BETWEEN THE OPTICAL CAM DEVICE AND THE OPTICAL UNIT, MEANS CONTROLLED BY THE OPTICAL UNIT FOR CAUSING RELATIVE WORKING MOVEMENTS BETWEEN THE OPTICAL UNIT AND THE OPTICAL CAM DEVICE TO TAKE PLACE TRANSVERSELY TO SUCH RELATIVE TRAVERSING MOVEMENT WHEREBY THE OPTICAL UNIT IS CAUSED ACCURATELY TO FOLLOW THE CURVED LINE OF THE OPTICAL CAM DEVICE, TRANSMISSION MEANS OPERATED IN ACCORDANCE WITH SUCH RELATIVE WORKING MOVEMENTS FOR EFFECTING A RELATIVE TRANSLATIONAL CORRECTING MOVEMENT BETWEEN THE WORKHOLDER AND THE TOOLHOLDER IN ACCORDANCE WITH THE DEVIATIONS OF THE DESIRED ASPHERIC SURFACE FROM THE BASIC SPHERICAL SURFACE, SUCH TRANSLATIONAL CORRECTING MOVEMENT BEING SUPERIMPOSED ON THE RELATIVE ROTATIONAL TRANSVERSING MOVEMENT BETWEEN THE WORKHOLDER AND THE TOOLHOLDER, AND MEANS WHEREBY SUCH SUPERIMPOSED TRANSLATIONAL CORRECTING MOVEMENT IS CAUSED TO TAKE PLACE IN A FIXED DIRECTION IN A PLANE AT RIGHT ANGLES TO THE FIXED PIVOT AXIS.