A 0.75-mW laser emits a narrow beam of light that enters the eye, as shown in FIGURE 25-41.
In Figure 25-41

(a) How much energy is absorbed by the eye in 0.2 s?
(b) The eye focuses this beam to a tiny spot on the retina, perhaps 5.0 mm in diameter. What is the average intensity of light (in W/cm2) at this spot?
(c) Damage to the retina can occur if the average intensity of light exceeds 1.0 × 10-2 W/cm2.
By what factor has the intensity of this laser beam exceeded the safe value?

Transcribed Image Text:

d = 5.0 µm