| 摘要 |
854,276. Photo-electric control systems. ZEISS STIFTUNG, C., [trading as ZEISS, C. [Firm of]]. Aug. 27, 1959 [Aug. 30, 1958 (2); Sept. 6, 1958], No. 29275/59. Class 40(3). [Also in Groups XX and XL(a)] In apparatus for boring holes in a workpiece 19 with a beam of charged particles, light from a source 34 is directed downwards on to the workpiece and the working region is viewed by the reflected light transmitted through the objective lens 28 and deflected by the mirror 30 to a micro-projection device at 27, a thermocouple or photo-electric cell in the path of the projected image switching off the beam of charged particles when the workpiece is bored through and no radiation appears.
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