This is the first of a series of planned articles on laser scanning technology. The format is novel - configured to provide a convenient source of authoritative technical material. Each article is arranged to fit into a standard 8.5" x 11" notebook page, adapted for 3-hole binding. The reader can, in this way, assemble a cohesive set of reference documents which merit archival access.

Introduction

Laser scanning is now almost synonymous with the general field of optical scanning. It has earned this prominence over 27 years of development and disciplined application to the spatial control of optical radiation. Some of its distinguishing features are:

1. Since the typical laser provides good monochromaticity and high coherence, it is often assumed, for first analysis and synthesis, as allowing diffraction-limited performance. Practical derating is applied, as in any well-designed system.

2. The laser beam is scanned in a pattern-either to convey its energy over a photosensitive medium to impart a physical change (e.g., recording, marking, engraving), or to allow detection of its retroreflection or scatter for conversion to an electrical signal (e.g., flying-spot scanning).

3. The dominant application of actively scanned laser beams is for information handling at the input and output; reading and writing; scanning (digitizing), printing, and information display. The typical scanned laser is of relatively low power, and provides a continuous wave (cw) beam which may be intensity-modulated with a temporal stream of information.

Much of the technology which derives from active laser scanning applies to passive optical scanning, in which ambient illumination scattered from a distant target is conveyed through similar scanning optics to a detector for sensing remote patterned radiation. Thus, laser scanning technology provides much of the discipline for passive optical scanning as well. Table 1 expresses some of the diverse applications of laser scanning technology and demonstrates its breadth and continuing growth in our expanding information age.