System and method for radius of curvature modification of optical plates and lenses by irradiation with optical energy
The present disclosure relates to an apparatus for modifying a curvature of a thin plate optic using controlled heat and densification of portions of the optic. In one embodiment the system has a support structure for supporting the optic about a perimeter thereof, a laser configured to generate a beam having a predetermined energy, and the beam being directed at one surface of the optic. The beam heats and densifies portions of the optic to create a force on the optic. The force induces a stress produces a controlled deformation of the optic. The controlled deformation at least one of modifies a curvature of, or corrects a defect in, the optic.
1 . An apparatus for modifying a curvature of a circularly shaped, flat plate having a flat surface, comprising:
an electronic controller;
a memory accessible by the electronic controller;
a laser configured to communicate with the electronic controller and to generate a beam having a predetermined energy and a beam annular radius r 0 ;
a software module for storing at least one of: an algorithm for beam control or power control over the laser;
an acousto-optic modulator for controlling an amount of beam diffraction imposed on the beam prior to passing the beam to the flat plate, wherein the flat plate has a radius r,
a support structure for supporting the flat plate only about a plurality of spaced apart peripheral edges thereof to enable deformation of the flat plate along an axis normal to the flat surface of the flat plate;
the beam from the laser being directed at the flat surface of the flat plate;
the beam being controlled by the electronic controller to create a force distribution created by the beam, which creates a line load being applied to the flat plate, in addition to a width of the force distribution, a poisson's ratio of material making up the flat plate, a radius r of the flat plate, a thickness of the flat plate, and a beam annular radius r 0 , and the beam further being controlled by the electronic controller in accordance with a selected one of the algorithm for beam control or by the power control over the laser; and
the beam being controlled by the controller to trace a select path on the one surface of the flat plate, to heat and densify portions of the flat plate to create a force on the flat plate, the force acting in the axis normal to the flat plate causing a stress which induces a controlled degree of deformation of the flat plate at an axial center of the plate and along the axis normal to the plate, to modify a curvature of the plate in a manner to produce a continuous, uniform spherical curvature over a full area of the flat plate, and the deformation being maximized at an axial center of the flat plate and controlled by the predetermined energy of the beam at select locations on the flat plate.
2 . The apparatus of claim 1 , further comprising a beam steering system configured to move the beam in a desired path to trace at least one line segment on the one surface of the flat plate.
3 . The apparatus of claim 2 , wherein the at least one line segment comprises a non-straight path, and the line load created comprises a line force.
4 . The apparatus of claim 2 , wherein the desired path comprises a circular path, and the line load created comprises a line force.
5 . The apparatus of claim 2 , wherein the desired path comprises a complete circular path, and the line load created comprises a line force.
6 . The apparatus of claim 2 , wherein the at least one line segment comprises a plurality of non-straight line segments.
7 . The apparatus of claim 2 , wherein the beam steering system comprises a galvanometer.
8 . The apparatus of claim 7 , further comprising:
a pickoff mirror configured to receive an image of the flat plate after the beam has passed back through the galvanometer, and to route the image to an imaging subsystem; and
an imaging system having a charge coupled display (CCD) for receiving a visible portion of the beam returned back from the galvanometer.
9 . The apparatus of claim 1 , wherein the laser comprises a CO 2 laser.
10 . The apparatus of claim 1 , further comprising a beam dump for receiving a portion of the beam from the acousto-optic modulator.
11 . The apparatus of claim 1 , further comprising:
a wedged optic responsive to the beam for passing only a predetermined portion of the beam generated by the laser;
a pickoff power meter configured to receive the passed predetermined portion of the beam from the wedged optic, the passed predetermined portion of the beam being used by the pickoff power meter for measuring a power of the beam; and
the electronic controller in communication with the pickoff power meter for assisting in controlling a power level of the beam.
12 . The apparatus of claim 1 , wherein the support structure includes a heated chamber.