A helium-neon laser ( = 633 nm) is built with a glass tube of inside diameter 1.0

A helium-neon laser (λ = 633 nm) is built with a glass tube of inside diameter 1.0 mm, as shown in FIGURE P33.62. One mirror is partially transmitting to allow the laser beam out. An electrical discharge in the tube causes it to glow like a neon light.From an optical perspective, the laser beam is a light wave that diffracts out through a 1.0-mm-diameter circular opening.

a. Can a laser beam be perfectly parallel, with no spreading? Why or why not?b. The angle θ₁ to the first minimum is called the divergence angle of a laser beam. What is the divergence angle of this laser beam?c. What is the diameter (in mm) of the laser beam after it travels 3.0 m?d. What is the diameter of the laser beam after it travels 1.0 km?

Transcribed Image Text:

Mirror Laser Discharge 1.0 mm beam Partial Electrodes mirror Power supply FIGURE P33.62