Effects on soft tissue produced by a visible violet diode laser

A violet laser with an oscillating wavelength of 405 ran has recently been developed in industry. Laser irradiation at this wavelength penetrates tissue less aggressively than Nd:YAG and diode laser irradiation at wavelengths of 810 nm, and more aggressively than irradiation by carbon dioxide laser. Further, protein is reported to absorb this 405 nm wavelength at high rates. This study was conducted to evaluate the effect of the violet laser on soft tissue in vitro. A prototype violet diode laser produced by Sumitomo Electric Industries was used. This laser irradiates with a continuous wave at a wavelength of 405 run. Soft tissue samples were irradiated by the device at output powers in a range from 850 mW to 2400 mW as the irradiated samples were conveyed at a scanning speed of I mm/sec. The beam diameter was about 270 mu m. The irradiated samples were observed by a stereoscopic microscope, fixed with a 10% neutral formalin aqueous solution, and histologically examined. Irradiation by the device vaporized a U-shaped section of tissue to a depth of about 350 to 900 pm. A denatured layer measuring 300 to 450 mu m in width was observed under the carbonization layer. The depth of vaporization increased in proportion to the power. These results indicate that a violet laser has good potential to become an effective laser for the cutting and coagulation of soft tissue.