Which of the following best defines the Nominal Ocular Hazard Distance (NOHD)?

Nominal Ocular Hazard Distance (NOHD) refers specifically to the distance from a laser source within which a person's eye could potentially be exposed to hazardous levels of laser radiation that may cause injury. This definition is critical in understanding laser safety, as it helps determine the safe zones around laser operations. The measurement of NOHD is based on the characteristics of the laser, such as its power, wavelength, and beam divergence, and is essential for formulating safety protocols and ensuring proper protective measures are in place.

The other options do not accurately capture the critical concept of NOHD. Some discuss distances where different safety measures may be applied or assumed, but they do not align with the specific context of potential eye exposure leading to injury, which is at the heart of the definition for NOHD. Understanding this helps personnel maintain a safe working environment around laser operations.