a) Selection of laser (spectral characteristics and power). 
b) Laser optics. 
c) Scanning (mechanical and non-mechanical) mechanisms. 
d) Film selection (image quality and laser response coupling). 
e) Precision film transport and handling. 
f) Laser beam modulation. 
$e) Reliability. 
h) Operational and environmental considerations. 
This is a simple block diagram of a laser scanner and recorder. 
The elements shown in dotted form are used only during recording. So for 
scanning, the laser beam passes through the laser optics (which consists 
of a beam expander, to expand the collimated bundle to a diameter which will 
flood the objective lens, and the objective lens, which focuses the beam 
to a diffraction limited spot at the film plane) and is reflected off the 
mirrored surface of the spinner to the film plane. The light energy transmitted 
through the film is collected by an optical system and measured by a photo- 
multiplier tube. The output signal produced by the PMT as the spinner rotates 
at high speed is a time-varying measure of the density of the film. As the 
spinner rotates the film is advanced so that adjacent scan lines are contiguous. 
Precision control of both the spinner rotation and the film drive is required 
so that subsequent recording of the output signal for re-creation of the 
image is possible with precise geometrical fidelity. For recording, the 
film is replaced with sensitized film and the input video signal is used 
to modulate the intensity of the laser beam as it is scanned over the film. 
CBS Laboratories has designed a number of scanner and recorder 
systems utilizing this principle over the last several years. These have