Pulsed Laser Tissue Interaction

Walsh, Joseph T.; Leeuwen, Ton G. van; Jansen, E.; Motamedi, Massoud; Welch, Ashley J.

doi:10.1007/978-90-481-8831-4_15

Cited by 4 publications

(5 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The optical penetration depth

δ

, changes significantly across the wavelengths used in this work. The influence of heat conduction on energy deposition can be estimated by the thermal diffusion time

τ_{d}

. Spatially confined effects can be achieved by using laser pulse durations that are shorter than the thermal diffusion time of the heated volume .…”

Section: Methodsmentioning

confidence: 99%

“…The blow‐off model assumes that the Lambert–Beer law accurately describes the spatial distribution of absorbed laser energy and that a finite threshold radiant exposure H th is required to initiate ablation . Due to using micro‐beams with small spot sizes and the fact that the vaporization is limited to a small fraction of the irradiated target volume, the latent heat of vaporization can be neglected and the ablation threshold can be reduced to a partial vaporization model :

H_{t h} = \frac{1}{μ_{a}} ϱ true(c_{v} normalΔ T true)

where

ϱ

= 1.05 g/cm 3 is the density of skin, c v = 3.39 J/gK is the specific heat capacity of skin at T v = 373 K, and Δ T = T v − T 0 is the absolute temperature rise .…”

Section: Methodsmentioning

confidence: 99%

“…For laser ablation, the heated volume is typically a layer of the thickness of the optical penetration depth

δ

and the characteristic thermal diffusion time is given as:

τ_{d} = \frac{1}{μ_{a}^{2} κ} = \frac{δ^{2}}{κ}

where µ a denotes the absorption coefficient, and κ = 1.43 × 10 −3 cm 2 s −1 is the thermal diffusivity of water . For wavelengths with an optical penetration larger than the focused laser spot radius (about 33 μm) the following equation is used as defined by McKenzie et al and Walsh et al

τ_{d} = \frac{δ^{2}}{4 κ}

…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Assessment of skin lesions produced by focused, tunable, mid‐infrared chalcogenide laser radiation

Evers

Casper

et al. 2018

Lasers Surg Med

View full text Add to dashboard Cite

The tunable laser system provides a useful research tool to investigate specific laser parameters such as wavelength on lesion shape, ablation depth and thermal tissue damage. It also allows for customization of the characteristics of laser lesions and therefore facilitates the selection of suitable laser parameters for optimized fractional laser treatments. Lasers Surg. Med. 50:961-972, 2018.© 2018 Wiley Periodicals, Inc.

show abstract

“…The optical penetration depth

δ

, changes significantly across the wavelengths used in this work. The influence of heat conduction on energy deposition can be estimated by the thermal diffusion time

τ_{d}

. Spatially confined effects can be achieved by using laser pulse durations that are shorter than the thermal diffusion time of the heated volume .…”

Section: Methodsmentioning

confidence: 99%

H_{t h} = \frac{1}{μ_{a}} ϱ true(c_{v} normalΔ T true)

where

ϱ

= 1.05 g/cm 3 is the density of skin, c v = 3.39 J/gK is the specific heat capacity of skin at T v = 373 K, and Δ T = T v − T 0 is the absolute temperature rise .…”

Section: Methodsmentioning

confidence: 99%

“…For laser ablation, the heated volume is typically a layer of the thickness of the optical penetration depth

δ

and the characteristic thermal diffusion time is given as:

τ_{d} = \frac{1}{μ_{a}^{2} κ} = \frac{δ^{2}}{κ}

τ_{d} = \frac{δ^{2}}{4 κ}

…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Assessment of skin lesions produced by focused, tunable, mid‐infrared chalcogenide laser radiation

Evers

Casper

et al. 2018

Lasers Surg Med

View full text Add to dashboard Cite

show abstract

“…b). The increased subsurface fluence and consequently the larger tissue temperature rise upon broadening of the irradiation beam is a well‐known effect . To isolate the effect of the incidence angle, a combination of 10° incidence angle and 3 mm beam diameter was also simulated (dotted lines).…”

Section: Discussionmentioning

confidence: 99%

Temperature Depth Profiles Induced in Human Skin In Vivo Using Pulsed 975 nm Irradiation

et al. 2019

View full text Add to dashboard Cite

Background and Objectives The aim of this study was to determine the temperature depth profiles induced in human skin in vivo by using a pulsed 975 nm diode laser (with 5 ms pulse duration) and compare them with those induced by the more common 532 nm (KTP) and 1,064 nm (Nd:YAG) lasers. Quantitative assessment of the energy deposition characteristics in human skin at 975 nm should help design of safe and effective treatment protocols when using such lasers. Study Design/Materials and Methods Temperature depth profiles induced in the human skin by the three lasers were determined using pulsed photothermal radiometry (PPTR). This technique involves time‐resolved measurement of mid‐infrared emission from the irradiated test site and reconstruction of the laser‐induced temperature profiles using an earlier developed optimization algorithm. Measurements were performed on volar sides of the forearms in seven volunteers with healthy skin. At irradiation spot diameters of 3–4 mm, the radiant exposures were 0.24, 0.36, and 5.7 J/cm2 for the 975, 532, and 1,064 nm lasers, respectively. Results Upon normalization to the same radiant exposure of 1 J/cm 2, the assessed maximum temperature rise in the epidermis averaged 0.8 °C for the 975 nm laser, 7.4 °C for the 532 nm, and 0.6 °C for the 1,064 nm laser. The characteristic subsurface depth to which 50% of the absorbed laser energy was deposited was on average 0.31 mm at 975 nm irradiation, and slightly deeper at 1,064 nm, and 0.15 mm at 532 nm. The experimentally obtained relations were reproduced in a dedicated numerical simulation. Conclusions The assessed energy deposition characteristics show that the pulsed 975 nm diode laser is very suitable for controlled heating of the upper dermis as required, for example, for nonablative skin rejuvenation. The risks of nonselective overheating of the epidermis and subcutis are significantly reduced in comparison with irradiation at 532 and 1,064 nm, respectively. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

show abstract

“…Numerous laser medical procedures and other biomedical applications involve generation of bubbles in tissue, in various possible geometric configurations, e.g. bubbles near a rigid or elastic boundary or bubbles near a combined boundary, consisting of a rigid surface and an elastic membrane in close proximity (Walsh et al, 2011;Vogel and Venugopalan, 2011). Such complex boundary geometry occurs, for example, in posterior capsulotomy surgical procedure where a membrane-like elastic tissue called posterior capsule surrounds a rigid artificial intraocular lens.…”

Section: Introductionmentioning

confidence: 99%

Laser-induced bubble dynamics inside and near a gap between a rigid boundary and an elastic membrane

Horvat

Orthaber

Schille

et al. 2018

International Journal of Multiphase Flow

View full text Add to dashboard Cite

Pulsed Laser Tissue Interaction

Cited by 4 publications

References 68 publications

Assessment of skin lesions produced by focused, tunable, mid‐infrared chalcogenide laser radiation

Assessment of skin lesions produced by focused, tunable, mid‐infrared chalcogenide laser radiation

Temperature Depth Profiles Induced in Human Skin In Vivo Using Pulsed 975 nm Irradiation

Laser-induced bubble dynamics inside and near a gap between a rigid boundary and an elastic membrane

Contact Info

Product

Resources

About