High-sensitivity, Single-beam N2 Measurements
We present a simple yet highly sensitive single-beam experimental technique for the determination of both the sign and magnitude of n2. The sample is moved along the z direction of a focused Gaussian beam while the repetitively pulsed laser energy is held fixed. The resultant plot of transmittance through an aperture in the far field yields a dispersion-shaped curve from which n2 is easily calculated. A transmittance change of 1% corresponds to a phase distortion of ≃ λ/250. We demonstrate this method on several materials using both CO2 and Nd:YAG laser pulses.
Sheikbahae, M.; Said, A. A.; and Vanstryland, E. W., "High-sensitivity, Single-beam N2 Measurements" (1989). Faculty Bibliography 1980s. 730.