Which of the following best describes Class 2 lasers?

• A. Low-power visible lasers; blinking normally protects eyes; hazard if stared >0.25 s
• B. High-power lasers hazardous under any viewing condition
• C. Intermediate-power lasers hazardous with collecting optics
• D. No hazard

Answer: (A)

Hazard levels for lasers depend on power and how you view them. Class 2 lasers are low-power devices that operate in the visible spectrum, so incidental viewing isn’t considered hazardous because the eye’s natural blink reflex protects you. In practice, if someone stares directly into the beam for more than about a quarter of a second, retinal damage can occur, but normal blinking usually ends exposure before that point. So the description that best fits Class 2 is a low-power visible laser with blinking reflex protecting the eye, and a hazard only if someone stares into the beam longer than about 0.25 seconds.

The other descriptions don’t fit: lasers described as hazardous under any viewing condition imply much higher power (not Class 2), those saying intermediate power with hazards when collecting optics point to higher classes, and saying there is no hazard at all ignores the real risk from direct, prolonged viewing.