Which laser class has an output power of less than 5 mW?

The correct choice is associated with Class 2a lasers, which are defined as having an output power of 1 mW to 5 mW. These lasers are typically considered low risk for eye injury under normal circumstances because the human blink reflex provides some protection from exposure. Class 2a lasers are not typically hazardous unless a person stares directly into the beam for an extended period; therefore, they are often found in consumer products and applications that are generally safe for the public.

In contrast, Class 3a lasers have an output power between 5 mW and 500 mW, which can present a greater risk of eye injury if directly viewed. Class 3b lasers range from 500 mW to 5 W and can be hazardous with direct exposure, while Class 4 lasers exceed 5 W and can cause severe injury not only to eyes but also to skin and can even create fire hazards. Understanding the classification system for lasers helps in assessing their safety and potential risks in different environments.