ABOUT THIS CHAPTER

Chapter 11 described major uses of low-power lasers, loosely defined as those that do not change objects not intended to be lightsensitive. This chapter covers major applications of high-power lasers, which cause significant changes to the materials they illuminate. The applications practical today include cutting, welding, drilling, and marking in industry, some specialized tasks in the manufacture of electronic components, and a variety of medical treatments. Several other applications for high-power lasers remain in various stages of development, including causing and controlling chemical reactions, laser weapons, and thermonuclear fusion.

12.1 HIGH- VERSUS LOW-POWER LASER APPLICATIONS

The line between high- and low-power laser applications is based on how the laser beam affects materials. If a laser cuts or welds a material, it clearly is making a major change, whether the material is sheet metal in a factory or living tissue during surgery. Marking serial numbers or product codes on equipment is not quite as clear, but is considered materials-working if the laser beam etches away surface material to mark the object.

On the other hand, it is reasonable to consider laser applications low-power if they change properties of light-sensitive materials, such as laser printing and optical data storage. Part of our rationale is that ordinary light can make similar changes, like the exposure of photographic film. Part is that some of these applications are closely related to other low-power applications; for example, optical data storage by writing on disks is one of a family of optical disk applications that logically belong together. A final element of the rationale is the need to make some separation lest these two chapters merge into a single monstrous and unmanageable whole.