Positioning device

Abstract

Abstract PURPOSE: To enable distance measurement with high accuracy of a quarter wavelength by projecting a laser beam on an object to be measured and subjecting the interference fringes of reflected light to an arithmetic processing. CONSTITUTION: The laser beam outputted from an oscillator 1 is focused by an objective lens 5 and projects the reference plane of an electrode 6 for electric discharge machining. The reflected light thereof is detected by a photodetecting element 13 and after the output thereof is amplified 14, the output is compared with a preset reference value in a comparator 16, the differential signal of which is applied to a motor driving circuit 11 and, therefore, the lens 5 moves to the position where the focus O aligns to the reference plane of the electrode 6, then the lens stops moving. The lens 5 moves to the point where the focus aligns to the reference plane of a work 7 when the electrode 6 is raised and the work is irradiated. On the other hand, the laser beam is split by a half mirror 3. The split beam is reflected by a reflecting cube 12 fixed to the lens 5 via a rectangular reflecting mirror 22 and interferes with the fixed wave from a reflecting film 24. The interference fringes generated during the movement of the lens 5 are, therefore, detected and are subjected to waveform forming and counting, by which the distance between the electrode 6 and the work 7 is computed. COPYRIGHT: (C)1989,JPO&Japio

Inventors

• 👤 Kiyoshi Inoue

Bibliographic Details