The penetration of laser light has been measured in normal human aorta and in calcified atherosclerotic lesions. The optical attenuation has been measured at 488, 514.5 and 633 run. Typical values for the penetration depth at 488 and 514.5 nm are in the range 0.3 - 0.4 mm. The corresponding values for 633 nm are three times larger i.e. in the range 0.7 - 1.1 mm.
The fluorescence spectra excited at one of the lines from an argon ion laser have been examined. The measurements emphasize evaluation of the integrated fluorescence spectrum. The highest intensities are found in atherosclerotic lesions and in the elastic fibres of the tunica media. These values are typically three times larger than the fluorescent intensity from the intima and about one order of magnitude larger than the corresponding values from the adipose tissue surrounding the vessel.