| 摘要 |
<p>1,239,777. Removing metal by fusion. NATIONAL RESEARCH DEVELOPMENT CORP. 1 Oct., 1969 [3 Oct., 1968], No. 46938/68. Heading B3V. [Also in Division H1] A workpiece 19 is shaped by projecting a constant intensity portion of a laser beam through the transparent parts of a mask 17 so that an image is formed on the workpiece 19 of at least part of the mask 17. The laser beam 11 from a ruby laser 10 is diverged by passing it through longitudinally movable concave lenses 13, 14 and passed through a filter 15 to attenuate the beam. After passing through a lens 18, the beam is passed through the mask 17 to cause numerals to be projected via a lens 21 on to the workpiece 19 comprising a metal film, e.g. Al, Ag, Ti on a substrate. The film is evaporated at areas of the image corresponding to transparent areas of the mask 17. Material may alternatively be deposited on the workpiece 19 by placing a gelatine film with an emulsion or coating of the material to be deposited in contact with the workpiece 19. The apparatus is provided with a viewing and alignment microscope 24, television viewer 25, a beam splitter 22 which is used with an autocollimator 23 or gas laser for checking coincidence and indexing means 31, 32 for the mask 17 and workpiece 19 so that different profiles can be machined on different parts of the workpiece. The laser 10 is operated in the burst mode wherein each pulse envelope has a rise time of 150-500 microseconds controlled by a capacitor C n and inductor L n forming part of a delay line connected to a D.C. source 48 and a flash tube 47 for pumping the laser 10. Each pulse has a duration of 1-8 milliseconds controlled by the total capacitance and inductance of the delay line. The energy of the burst is 0À1-10 joules.</p> |
