| 摘要 |
PURPOSE:To enable the production of large-sized concave mirrors at a low cost, by a method wherein a concave plate is formed at a given temperature using a mold having a given surface coarseness after preheating a plate of a thermoplastic resin at a given temperature, and Al or Cr is electrodeposited thereon. CONSTITUTION:A plate of a thermoplastic resin is preheated at a temperature higher than a thermal deformation point or lower than a melting point thereof. A concave plate is formed by a direct pressure at a mold temperature of 20-40 deg.C lower than the thermal deformation point of the resin by the use of a convex upper mold, whose surface coarseness is 0.1S or less, and a concave mold having an optional surface coarseness. Al or Cr 1,000-9,000Angstrom in thickness is electrodeposited on the inside of the concave sheet to produce a concave mirror. A resin plate of 2-15mm. in thickness, such as polymethylmetaacrylate, polycarbonate, polyethylene, etc., are used for the production of the thermoplastic resin plate. From the economical viewpoint, a suitable size of the concave mirror available is 200- 500mm.phi. |
