In some types of optical spectroscopy, such as photoluminescence and Raman spectroscopy, a laser beam exits from a pupil and is focused on a sample to stimulate electromagnetic radiation from the sample. The focusing lens usually has an antireflective coating preventing any light loss. Assume a 100-mW laser is located 4.80 m from the lens, which has a focal length of 7.00 cm.
(a) How far from the lens should the sample be located so that an image of the laser exit pupil is formed on the surface of the sample?
(b) If the diameter of the laser exit pupil is 5.00 mm, what is the diameter of the light spot on the sample?
(c) What is the light intensity at the spot?