Two-photon absorption an ADP and KD*P at 266.1 nm

We present absolute measurements of two-photon absorption (TPA) coefficients of ADP and KD*P at 266.1 nm. Values of
\beta = 11 \pm 3 \times 10^{-11}
cm/W for ADP and
2.7 \pm 0.7 \times 10^{-11}
cm/W for KD*P were determined. The effect of the pulse profile in space and time on the numerical value of β is discussed. The limitation which this degree of nonlinear absorption places on second harmonic conversion from 532 nm is investigated.