Fabrication of cooled faceplate segmented aperture mirrors (SAM) by electroforming

摘要

An electroforming method is described for making a cooled segmented aperture (SAM) mirror suitable for use with high energy laser irradiation. The method avoids the problems associated with discrete segment SAMs by using electroforming to fabricate a continuous faceplate having a surface shape of the desired array of segments and coolant channels just below the optical surface to provide improved performance under high energy laser irradiation. A master mirror is fabricated from discrete segments. Raised circular lands on the rear of the segments aid alignment of the segments. A negative faceplate is electroformed on the master mirror. A positive faceplate is electroformed on the negative faceplate. Cooling channels are electrical discharge machined into the back of the positive faceplate and additional material electrodeposited to close the channels. A manifold for coolant flow through the cooling channels and bosses for safety screws are attached to the back of the positive faceplate and held in place by a further electrodeposition. Large substrates are epoxy bonded to the electroformed negative and positive faceplate deposits before separation from their respective masters to prevent elastic deformation of the deposits. Separator bars are used to facilitate separation. The structure of the CSA mirror made from the method is also disclosed.