Laser Physics & Safety Flashcards
7 cards from real CLT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Laser Physics & Safety flashcards as text
Which laser modality produces the shortest pulse durations, enabling high peak powers without excessive average power?
Answer: Mode-locked lasers
Mode-locked lasers generate pulses in the femtosecond to picosecond range by locking the phases of multiple longitudinal modes.
In laser safety, what does the term 'diffuse reflection' refer to?
Answer: Scattering of laser light in multiple directions from a matte surface
Diffuse reflection scatters laser energy in many directions from rough surfaces, generally reducing intensity compared to specular reflection.
Which standard governs the safe use of lasers in medical facilities in the United States?
Answer: ANSI Z136.3
ANSI Z136.3 specifically addresses safe use of lasers in health care settings, complementing the general ANSI Z136.1 standard.
A laser operates at 532 nm with 100 mW CW output and a 1 mm beam diameter. What immediate hazard classification concern applies most?
Answer: Retinal burn risk because 532 nm is focused by the eye
Green 532 nm is in the retinal hazard zone (400–1400 nm); the eye focuses it to a tiny retinal spot, greatly increasing irradiance and burn risk.
What is the purpose of an optical isolator placed at a laser output?
Answer: To prevent back-reflections from re-entering and destabilizing the laser cavity
An optical isolator uses polarization and a Faraday rotator to allow light to pass in one direction only, protecting the laser from destabilizing back-reflections.
Which factor doubles when the beam diameter is halved at constant power, directly affecting irradiance?
Answer: Irradiance increases by a factor of 4
Irradiance (W/cm²) depends on beam area, which scales with the square of diameter; halving diameter reduces area by 4, quadrupling irradiance.
Which laser transition type involves electrons returning from a metastable excited state to the ground state?
Answer: Three-level laser system
In a three-level system, the lower laser level is the ground state; population inversion requires pumping over 50% of atoms to maintain gain.