A laser cavity has a flat mirror and a spherical mirror with radius of curvature of 40 cm. the mirrors are separated by 20 cm. the flat mirror is partially transparent, while the spherical mirror is perfectly reflecting. an output of 2 mW at a wavelength of 0.543 um (micrometer, green) is emitted by the laser.
a) Demonstrate that the cavity is stable.
b) what is the half angle of the beam divergence (in radians)?
c) an opaque screen with a circular hole of radius a is placed at a distance of 40 cm from the flat mirror. A total power of 1 mW passes through the hole. Calculate the radius of “a” of the hole. Assume that the center of the hole coincides perfectly with the optical beam axis.