| 摘要 |
A refracting pattern is applied to a light transmitting sheet of polyvinyl chloride, polystyrene or polymethylmethacrylate by first heating the sheet soft (up to 150 DEG C.) and compression moulding it in a cool mould of appropriate shape by the rapid application of pressure (up to about 4 tons per square inch). The mould may be made up of metal cubes machined on one face with circular or spiral grooves and mounted side by side to form a plate of the desired size. It is stated that the method can be applied to glass. |
