CLT Laser Physics & Safety Principles 3

Question 1

Selective photothermolysis requires that the pulse duration be:

Accepted Answer

Equal to or shorter than the thermal relaxation time of the target chromophore

Answer

For selective photothermolysis, the pulse must confine heat to the target before it diffuses to surrounding tissue, requiring pulse duration ≤ thermal relaxation time.

Question 2

Which primary chromophore in skin has strong absorption peaks around 532 nm (green light)?

Accepted Answer

Oxyhemoglobin

Answer

Oxyhemoglobin has strong absorption peaks at approximately 418 nm, 542 nm, and 577 nm, making 532 nm lasers highly effective for vascular lesion treatment.

Question 3

In laser-tissue interaction, 'absorption' refers to:

Accepted Answer

The conversion of laser photon energy into heat or photochemical reactions within tissue

Answer

Absorption occurs when tissue molecules take up photon energy and convert it to heat or initiate photochemical reactions, producing the desired therapeutic effect.

Question 4

Water is the dominant chromophore for laser wavelengths in which range?

Accepted Answer

2,000–3,000 nm (mid-infrared)

Answer

Water has very high absorption coefficients in the mid-infrared range, with peaks near 2,940 nm (Er:YAG) and 10,600 nm (CO2), driving tissue ablation.

Question 5

Which tissue effect is most associated with ultra-short (nanosecond to picosecond) pulses at high peak power?

Accepted Answer

Photoacoustic/photomechanical effect

Answer

Ultra-short pulses create rapid thermoelastic expansion generating mechanical shockwaves, the mechanism underlying Q-switched laser tattoo removal.

(CLT) Certified Laser Therapist Practice Test

(CLT) Certified Laser Therapist Practice Test

CLT Laser Physics & Safety Principles 3