How is a laser defined according to DA Pam 385-63?

The correct choice describes a laser as a device that produces a narrow beam of intense light. This definition encapsulates the fundamental operation of a laser. Lasers emit light through a process called stimulated emission, resulting in coherent, monochromatic, and directional light. This intense and focused beam is what sets lasers apart from other light sources, making them useful in various applications, including military, medical, and engineering fields.

Understanding the nature of lasers is crucial in the context of range safety, particularly because they can pose hazards if used improperly in environments like shooting ranges. The other options, while they describe certain functions or applications of light, do not accurately define a laser. For example, measuring devices and signaling lights may utilize different principles and do not convey the unique characteristics that define a laser's operation. Thus, recognizing that a laser is fundamentally a device that produces a narrow beam of intense light is essential for comprehending its use and implications in safety protocols.