Penetration of laser light at 808 and 980 nm in bovine tissue samples.

OBJECTIVE The purpose of this study was to compare the penetration of 808 and 980 nm laser light through bovine tissue samples 18-95 mm thick. BACKGROUND DATA Low-level laser therapy (LLLT) is frequently used to treat musculoskeletal pathologies. Some of the therapeutic targets are several centimeters deep. METHODS Laser light at 808 and 980 nm (1 W/cm(2)) was projected through bovine tissue samples ranging in thickness from 18 to 95 mm. Power density measurements were taken for each wavelength at the various depths. RESULTS For 808 nm, 1 mW/cm(2) was achieved at 3.4 cm, but for 980 nm, 1 mW/cm(2) was achieved at only 2.2 cm depth of tissue. CONCLUSIONS It was determined that 808 nm of light penetrates as much as 54% deeper than 980 nm light in bovine tissue.