| 摘要 |
1305777 Photographic processes GENERAL ELECTRIC CO 5 May 1970 [5 May 1969] 21660/70 Heading G2C [Also in Division B6] A method of forming an imaged transparency comprises subjecting a sheet of polycarbonate resin to a homogeneous bombardment of charged nuclear particles to form damage tracks 14, selectively exposing a portion of the bombarded sheet (e.g. using metallic shield 22) to ultraviolet radiation 20 in an oxygen containing gas for a period required to alter the solubility of the damage tracks in the exposed area, etching the sheet to at least partially dissolve the tracks in the exposed area, annealing the sheet to obliterate the remaining damage tracks and further etching the sheet to enlarge the previously etched apertures. The resulting sheet may be employed as a transparency in a conventional projection system wherein an image of the shield 22 is transmitted to a projection screen. |
