Consider a TEM00 laser (λ = 632.8 nm) with a maximum output power of 2.7 kW andinitial beam diameter of 1 cm. The full angle of divergence is measured and found tobe 8.16x10-5 rad. The laser is used to process gold at a normal angle of incidence. Thedistance from the source to the workpiece along the optical axis is 1 m. Answer thefollowing:a) The laser has a 2 m long resonant cavity. What is the longitudinal modenumber closest to the operating wavelength? Assume a refractive indexfor the cavity of 1.b) What is the peak intensity incident on the surface?c) What is the penetration depth of the beam?d) What is the coefficient of reflection for processing of gold at an incidentangle of 45o?e) As part of a risk assessment, you have been tasked with determining thenominal ocular hazard distance for the laser. Assume an MPE of 25.46W/m2.

Consider a TEM00 laser (λ = 632.8 nm) with a maximum output power of 2.7 kW and
initial beam diameter of 1 cm. The full angle of divergence is measured and found to
be 8.16x10-5 rad. The laser is used to process gold at a normal angle of incidence. The
distance from the source to the workpiece along the optical axis is 1 m. Answer the
following:
a) The laser has a 2 m long resonant cavity. What is the longitudinal mode
number closest to the operating wavelength? Assume a refractive index
for the cavity of 1.
b) What is the peak intensity incident on the surface?
c) What is the penetration depth of the beam?
d) What is the coefficient of reflection for processing of gold at an incident
angle of 45o?
e) As part of a risk assessment, you have been tasked with determining the
nominal ocular hazard distance for the laser. Assume an MPE of 25.46
W/m2.