|
In large-scale high-power laser devices, the mid-spatial-frequency(MSF) error of the transmitted wavefront of the large-aperture spherical lens has a direct impact on the energy scattering of the high power laser. This paper proposes a technology about correction of MSF error of large-aperture spherical lens based on computer numerical control polishing. A smooth polishing theoretical model is established for spherical lens and the removal function morphology is optimized. To make a better MSF error convergence, the rigid conformed tool is designed and assembled. The polishing tool and the main axle are connected by a high-precision universal joint, so that the polishing pad can be flexibly attached to the surface of the workpiece when the tool is running. This makes it able to polish the square spherical workpiece with large curvature radius by the processing method of planar workpiece. In the earlier stage, two kinds of path are applied to converge the low- frequency error by crossing each other. Then the random path is applied for MSF error convergence. By the experimental varification of Four fused silica spherical lens with aperture of 440 mm × 440 mm, the RMS value of the PSD1 frequency band of the lens’ transmitted wavefront error is finally converg-ence to 2.2 nm through once MSF error correction.
|
