Influence of femtosecond laser pulse irradiation on the viability of cells at 1035, 517, and 345 nm

We report on the influence of femtosecond laser pulses at different wavelengths (1035, 517, and 345 nm) on chinese hamster ovary cells exposed to intense radiation. The aim of the study was to determine the mean power thresholds from which the cells were influenced by the laser radiation up to irreversible cell damage. An influence of the wavelength has been shown. The damage threshold is lower in the ultraviolet (UV) than in the infrared (IR) by a factor of 5-6. At the green wavelength the threshold value was higher due to the low absorption (i.e., a relatively high transmission). The range between the lowest power where a loss of viability could be observed (25 mu W) and the mean power for direct cell damage (45 mu W) is 20 mu W in the UV. The corresponding range in the IR is between 75 and 240 mu W and thus about 165 mu W broad: In the case of UV irradiation, the cells seem to be unaffected close to the ablation or damage threshold at low energy pulses.