What are low-power visible lasers, that are considered not strong enough to damage a person's eyes because a person will normally blink and look away, however may not be safe for a person who deliberately stares into the laser beam for longer than 0.25 second?

• A. Class 1
• B. Class 2M
• C. Class 2
• D. Class 3R

Answer: (C)

Class 2 lasers are low-power visible lasers with output up to about 1 milliwatt. They’re considered safe for normal viewing because the eye’s natural blink reflex typically protects you within about a quarter of a second. If you blink or look away quickly, the beam doesn’t have time to injure the retina. But if someone deliberately stares into the beam for longer than roughly 0.25 seconds, enough energy can reach the eye to cause damage. That combination of a short blink-protected exposure time and visible light power is why this option fits the description.

The other classifications don’t match as well: Class 1 is safe under all conditions, so it doesn’t rely on a blink to protect you. Class 2M is similar but includes restrictions when using magnifying optics, which isn’t part of the scenario. Class 3R involves higher power and can pose a hazard even with brief exposures, so it doesn’t fit the idea of a beam safe due to blinking.