Advanced Laser Image Recorder

Abstract
A laser image recorder is described, which is unique because of its advanced design and the state-of-the-art components employed to achieve high performance and versatility. The critical components are the pyramidal mirror scanner and the beam focusing lens. The scanner has a six-facet, beryllium mirror accurate to 0.33 sec of arc and rotating at 0–50,000 rpm on air bearings. A rapid change in speed is an important feature of this scanner. The focusing lens is diffraction limited with a flat field of 54°, allowing a 90% duty cycle and the use of photographic film transported by a cylindrical drum. The lens converts the constant angular velocity of the reflected beam to a constant scanning velocity of the focused spot with a linearity of 0.05%. Maximum number of picture elements per line is 36,800 over a format of 228.6 mm.