Laser spot size and beam profile studies for tissue welding applications

Nathaniel M. Fried*, Vincent C. Hung, Joseph T. Walsh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We evaluated the effect of changes in laser spot size and beam profile on the thermal denaturation zone produced during laser skin welding. Our objective was to limit heating of the tissue surface, while creating enough thermal denaturation in the deeper layers of the dermis to produce full-thickness welds. Two-cm-long, full-thickness incisions were made on the backs of guinea pigs, in vivo. India ink was used as an absorber. Continuous-wave, 1.06-μm, Nd:YAG laser radiation was scanned over the incisions, producing approximately 100 ms pulses. Cooling times of 10.0 s between scans were used. Laser spot diameters of 1, 2, 4, and 6 mm were studied, with powers of 1, 4, 16, and 36 W, respectively. The irradiance remained constant at 127 W/cm2. 1, 2, and 4 mm diameter spots produced thermal denaturation to a depth of 570±100 μm, 970±210 μm, and 1470±190 μm, respectively. The 6-mm-diameter spot produced full-thickness welds (1900 μm), but also burns due to the high incident power. Monte Carlo simulations were also conducted, varying the laser spot diameter and beam profile. The simulations verified that an increase in laser spot diameter results in an increase in the penetration depth of radiation into the tissue.

Original languageEnglish (US)
Pages (from-to)111-119
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume3590
StatePublished - Jan 1 1999

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

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