| 摘要 |
In a method and apparatus for measuring the vertical position of a point relative to a reference point spaced laterally therefrom, a laser beam is directed horizontally from the reference point to impinge upon a receiver at the other point. The receiver consists of a vertical line of separate, adjacent photoelectric units each of which is narrower than the laser beam in the vertical direction. The photoelectric units are connected in parallel with an identical ohmic resistor connected between similar poles of each adjacent pair of photoelectric units forming a chain of series connected resistors. A switch and a current measuring device are connected in circuit with the photoelectric units and resistor chain so that the total current emanating from the illuminated photoelectric units, and the partial current flowing between the illuminated photoelectric elements and one end of the resistance chain, are measured alternately. The ratio of the two current measurements gives the position of the point at which the axis of the laser beam impinges upon the line of photoelectric units relative to the length of the line of units. The laser beam may be modulated, and in each photoelectric unit the laser beam received thereby may be divided with each division focused at an aperture through which it passed to a photocell, for reducing the effect of interference.
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