CORNEAL-TISSUE ABSORPTION-COEFFICIENTS FOR 193 AND 213-NM ULTRAVIOLET-RADIATION

The small-signal absorption coefficients of 193- and 213-nm nanosecond laser pulses in bovine corneal tissue have been studied. The absolute reflectance of a planar quartz-cornea interface was measured at vario us angles of incidence for low-intensity laser irradiation (i.e., puls e fluences 3 orders of magnitude below the ablation threshold). The re flectance-versus-angle data were analyzed by the use of Fresnel theory to estimate the effective complex index of refraction of the tissue. This analysis indicated corneal absorption coefficients of 39,900 +/- 9800 cm(-1) at 193 nm and 21,400 +/- 4900 cm(-1) at 213 nm.