| 摘要 |
A method of forming a light weight, closed-back mirror. The mirror is formed as a monolithic construction by the use of chemical vapour deposition techniques. A first deposition forms sheets of the material, which are machined to the proper size to form reinforcing ribs (42). A sacrificial mandrel (44) is formed with grooves (58) to receive the ribs in their assembled positions honeycomb. The upper surface of the mandrel is in proximity to the rear edges (36) of the ribs to form a substantially continuous surface. The mandrel and ribs are then subjected to a chemical vapour deposition process which forms a first coating upon the outer face of the mandrel, forming a back plate (20) and side wall (38). The mandrel is then turned over, and the base is removed by machining to expose the front edges (34) of the ribs. This process leaves islands (60) of mandrel material between the ribs to form a substantially continuous surface (62). The mandrel and ribs are then subjected to a chemical vapour deposition process. This forms a second coating upon the lower surface of the mandrel, used as the mirror face. To reduce weight, holes are drilled through the back plate, and the remaining, encapsulated, mandrel material is removed by oxidation. <IMAGE> <IMAGE> |
