Objective      To investigate the vaporization effect and the surrounding thermal coagulation effect of the radiation of picosecond pulsed Nd:YAG laser at wavelength of 1 064 nm on suckling porcine skin tissue.       Methods      A 1 064 nm pulse Nd:YAG laser with a pulse duration of 30 ps and a frequency of 10 Hz was used to radiate suckling porcine skin in vitro. The porcine skin tissues were irradiated with different pulse energies (20

40

60

80 and 100 mJ) for different time periods (2

5 and 10 s per time). So there produced 15 different lesioning points and 3 normal control points (0 mJ and 2

5 and 10 s endurance)

and every point was repeated for 3 times. After irradiation

the width and depth of the evaporated zones of the lesioning points were measured with ultra-depth field microscopy. The coronal plane sections of every lesioning point were made into tissue slices

and then stained with hematoxylin and eosin. By the means of taking photomicrographs

the widths of the coagulation necrosis zones were measured. Finally

the curve of doses and effects was drawn.       Results      The average width of the evaporated zones of the lesioning points was 1 168.85±188.57 μm (740.66～1 455.32)

while the depth was 412.16±289.84 μm (106.44～1 314.80)

and the average width of the coagulation necrosis zones was 141.10±47.68 μm (65.35～238.73 μm).       Conclusion      Picosecond pulsed Nd:YAG laser of 1 064 nm wavelength irradiates good vaporization effect on suckling porcine skin tissue

and the effect is positively correlated with the pulse energy and irradiation duration of every pulse. When the laser is evaporating target skin area

the caused thermal damage is limited in hundreds microns to the surrounding healthy tissues of the lesioning point.