Plastic mirror article and method of making same

A method of forming an optical quality first surface mirror from a sheet of relatively flexible thermoplastic material comprising the steps of:

• press polishing the sheet to form an optical quality smooth surface substantially free of surface irregularities;
• depositing a reflective coating on the smooth surface;
• scoring the sheet along a straight line on its reverse surface from the smooth surface to a depth that does not penetrate the sheet, thereby leaving a thin portion having minimal extend along the plane of the smooth surface perpendicular to the straight line;
• and
• folding the sheet to bring portions of the smooth surface toward one another such that the smooth surface in the vicinity of the fold is maintained in a rigid flat condition to provide a mirrored surface of optical flatness.

A method of forming an optical quality first surface mirror from a styrene sheet comprising the steps of:

• providing a master having an optically polished surface;
• placing a first surface of the styrene sheet against the polished surface of the master;
• exerting a pressure against the styrene sheet to urge the first surface into intimate contact with the polished surface of the master;
• heating the styrene sheet to a temperature at which the styrene material exhibits flow characteristics while maintaining the pressure;
• cooling the styrene sheet to a temperature below the temperature at which the styrene exhibits flow characteristice while maintaining the pressure;
• removing the styrene sheet from the master;
• depositing a reflective coating on the first surface of the styrene sheet;
• scoring the reverse surface of the styrene sheet from the first surface along a substantially straight line to a depth that does not penetrate the sheet to the first surface to form a thin region of minimal extend parallel to the first surface, thereby defining first and second portions of the styrene sheet on either side of the scored line;
• and
• folding the styrene sheet about the scored line such that portions of the reflective coating deposited on the first and second portions of the styrene sheet are brought toward one another to maintain portions of the reflective surface proximate the fold to a high degree of flatness, thereby providing an optical quality first surface mirror.