| 摘要 |
1,261,924. Measuring alignment photoelectrically. PHILIPS ELECTRONIC and ASSOCIATED INDUSTRIES Ltd. Feb. 27, 1969 [March 2, 1968], No. 10549/69. Heading G1A. The misalignment between the direction of movement of an object relative to a direction defined by a collimated beam of radiation is measured by rotating a plane parallel transparent block in the path of the beam and detecting the intensity variations of the beam, the detector or a member in the light path being attached to the object. In the arrangement of Fig. 1, the block 7 is mounted with its rotation axis just outside the boundary of the beam 2 from a laser 1. When the detector 2 attached to the object under investigation (a slide 4) is on the axis of the beam, its output, as the block is rotated, gives a symmetrical waveform of intensity against angle of rotation of the block, Fig. 2a (not shown), which can be displayed as an oscilloscope. If the axis of movement of the slide 4 (and thus the detector) moves off the beam e. g. such that its axis 6 is angularly displaced relative to beam 2, the detector output is asymmetrical, the amount of asymmetry being representative of the displacement. In other embodiments, the detector is fixed, the object under investigation having mounted thereon a rectroreflector and lens (13, 12). In one, this reflects the beam back via a plane mirror (14) to the detector, Fig. 3 (not shown) and in the other back via a half-silvered mirror (18) in the beam from the laser. |
