Ultra-violet light generation at 205 nm by two frequency doubling steps of a cw titanium-sapphire laser

We have built a source at 205 nm from a CW titanium-sapphire laser at 820 nm. Two successive frequency doubling steps are made in LBO and BBO crystals. The difficulties encountered with the BBO crystal account for the low output power. In a quasi-continuous regime we obtain 1 mW (peak power) at 205 nm for a fundamental power at 820 nm of 2.2 W. In these conditions, the life time of a point of the BBO crystal is several hours.