Fabrication of free-form lens with computer-controlled optical surfacing

摘要

Though Optical lens with free-form lens(FFL) can be significantly used in optocal rectification, it is very difficult to manufacture it. Computer-controlled optical surfacing technology is used to fabricate it efficiently. In the stage of figuring FFL, the component is fixed with vacuum flat sucking disk, then ground by the progressive mode while the abrasion wheel is trimmed on-line. A lapping and polishing tool that conforms to the shape of FFL is used to finish the optical mirror. Because FFL has no any constraints, general interferogram technique can not be applied to its measurement and the accuracy of three-coordinate measuring machine is too low. So a high-precision after forming is under tens of micron. Then the error correction technology is employed to improve surface precision. Getting input controlled variables from error dot matrix involves deconvolution. Least-square filtration is used to solve deconvolution and wavelet analysis is used to filter fringe and tip. Then the surface after error correction is measured again. So a closed loop is formed. The accuracy of optical mirror in our experiment is under 4 mu m while Ra is under 5nm.