Which statement describes Class 3R lasers?

Which statement describes Class 3R lasers?

• A. They are always hazardous under all viewing
• B. They are not hazardous
• C. They may be hazardous under direct and specular reflection viewing
• D. They are only hazardous if reflected diffusely

Answer: (C)

Class 3R lasers carry enough power to be dangerous to the eye if someone looks directly into the beam or into a mirror-like (specular) reflection. The retina can focus the light, concentrating it enough to cause damage even though the beam power is lower than higher-class lasers. However, light that reflects diffusely off rough surfaces is spread over many directions and typically has much lower irradiance, which is usually not hazardous. So the key idea is that direct viewing and specular reflections can pose a hazard, while diffuse reflections generally do not, making the statement that these lasers may be hazardous under direct and specular viewing the best description.

Class 3R lasers carry enough power to be dangerous to the eye if someone looks directly into the beam or into a mirror-like (specular) reflection. The retina can focus the light, concentrating it enough to cause damage even though the beam power is lower than higher-class lasers. However, light that reflects diffusely off rough surfaces is spread over many directions and typically has much lower irradiance, which is usually not hazardous. So the key idea is that direct viewing and specular reflections can pose a hazard, while diffuse reflections generally do not, making the statement that these lasers may be hazardous under direct and specular viewing the best description.