3 - 2
No. 99MBC071A
The configuration of the system is shown in the above block diagram. 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 process-
ing 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 system block diagram described in the previous page, the laser beam passed
through the collimator lens is made parallel and, at the same time, stopped down so
that the beam diameter is minimized at the measurement position.
