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No. 99MBC032A
The configuration of the system is shown in the block diagram described in the previous
page. A laser beam emitted from the laser oscillator is directed at the polygon mirror which
rotates at high speed and is synchronized by clock pulses. The laser beam that is reflected by
the polygon mirror is then collimated by the collimator lens towards the workpiece. As the
polygon mirror rotates, this horizontal beam scans the workpiece and the beam not obstructed
by the workpiece will reach the photoelectric element through the condenser lens and induce
an output voltage in the photoelectric element. The output voltage will change according to
the duration over which the laser beam is obstructed. Counting pulses generated during that
period are used to determine the dimension of the obstructed portion. This data is sent to the
CPU for processing and the dimensions are displayed digitally.
Consequently, either the dimensions of the workpiece (shadowed areas) or workpiece
clearances (highlighted areas) can be determined by specifying the segments to be measured.
TIP In the above system block diagram, the laser beam passed through the collimator
lens is made parallel and, at the same time, stopped down so that the beam diam-
eter is minimized at the measurement position.
