Laser Physics & Safety Principles 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 Principles flashcards as text
Selective photothermolysis requires that the pulse duration be:
Answer: Equal to or shorter than the thermal relaxation time of the target chromophore
For selective photothermolysis, the pulse must confine heat to the target before it diffuses to surrounding tissue, requiring pulse duration ≤ thermal relaxation time.
Which primary chromophore in skin has strong absorption peaks around 532 nm (green light)?
Answer: Oxyhemoglobin
Oxyhemoglobin has strong absorption peaks at approximately 418 nm, 542 nm, and 577 nm, making 532 nm lasers highly effective for vascular lesion treatment.
In laser-tissue interaction, 'absorption' refers to:
Answer: The conversion of laser photon energy into heat or photochemical reactions within tissue
Absorption occurs when tissue molecules take up photon energy and convert it to heat or initiate photochemical reactions, producing the desired therapeutic effect.
Water is the dominant chromophore for laser wavelengths in which range?
Answer: 2,000–3,000 nm (mid-infrared)
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.
Which tissue effect is most associated with ultra-short (nanosecond to picosecond) pulses at high peak power?
Answer: Photoacoustic/photomechanical effect
Ultra-short pulses create rapid thermoelastic expansion generating mechanical shockwaves, the mechanism underlying Q-switched laser tattoo removal.
Melanin's absorption spectrum across wavelengths is best described as:
Answer: Broad absorption from UV through visible (~250–1100 nm) with decreasing absorption at longer wavelengths
Melanin has broad, gradually decreasing absorption from UV through the near-infrared (~1100 nm), which is why multiple laser wavelengths can target pigmented lesions.
The depth of laser penetration in tissue is primarily determined by:
Answer: Wavelength and the tissue's absorption and scattering coefficients
Tissue penetration depth is governed by wavelength-dependent absorption and scattering coefficients, not by power level alone.