This paper evaluates the effect of laser spot diameter and beam profile on the shape of the thermal denaturation zone produced during laser tissue welding. 2-cm-long full-thickness incisions were made on the epilated backs of guinea pigs in vivo. India ink was used as an absorber and clamps were used to appose the incision edges. Welding was performed using continuous-wave 1.06-μm, Nd:YAG laser radiation scanned over the incisions to produce approx. 100-ms pulses. 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/cm 2. Monte Carlo simulations were also conducted to examine the effect of laser spot size and beam profile on the distribution of photons absorbed in the tissue. The laser spot diameter was varied from 1 to 6 mm. Gaussian, flat-top, dual Gaussian, and dual flat-top beam profiles were studied. The experimental results showed that 1-, 2-, 4-, and 6-mm-diameter spots produced thermal denaturation to an average depth of 570, 970, 1470, and 1900 μm, respectively. Monte Carlo simulations demonstrated that the most uniform distribution of photon absorption is achieved using large diameter dual flat-top beams.
|Original language||English (US)|
|Number of pages||9|
|Journal||IEEE Journal on Selected Topics in Quantum Electronics|
|State||Published - Jul 1999|
ASJC Scopus subject areas
- Electrical and Electronic Engineering
- Atomic and Molecular Physics, and Optics