Form error of optical surface repaired by wet-etch figuring

A wet-etch figuring method is presented to repair the form error of optical surface to avoid the subsurface damage and surface pollution caused by traditional polishing technology. The Marangoni effect is used to control the dwell time and dwell area of chemical solvent, and the optical surface is repaired by program control of a digital system. The surface roughness of the optical surface before and after processing is measured by a profilometer. Experimental results show that the form error of the optical surface can be decrease from 1.22λ(λ = 632 nm) to 0.66λ by the method in many wet-etch and a little wipe off surface figuring, but the optic surface roughness is invariable in test. The results also indicate that the method can improve the laser threshold of optical element.