The new correcting method of beam scanning distortion using the parabolic mirror is described.
On the screen, the scanning beam varies in scanning speed and beam diameter with deflection angle. Usually, F·θ lenses have been used to correct scanning speed and beam diameter distortion. In modulated beam scanning, scanning distortion can be corrected by modulating frequency control.
The simpler and more efficient correcting method of this distortion is achieved by the parabolic mirror. Good result was obtained when the distance from the scanner to the parabolic mirror was 0.665
f (
f is the focal length of the parabolic mirror) and the screen was set on the focal plane. In this case, the distortion of beam deflected from 0 to ±41 degrees was ±0.01%, and the beam diameter was diffraction limited one.
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