We have developed and analyzed a heated laminar airflow device which introduces easily varied aberrations into optical beam trains. The aberrator produced nearly sinusoidal optical path differences of modulation depth 0 to 2λ (peak to valley) at a 355-nm wavelength and a spatial frequency of ~2 cycles/cm. The phase modulation was measured via lateral shearing interferometry and agreed with a sinusoidal near field phase model to ~10%. The far field intensity profile was in qualitative agreement with the theory of focused sinusoidal phase gratings.
L. P. Schelonka, K. R. Calahan, and C. M. Clayton, "Variable phase grating optical aberrator," Appl. Opt. 27, 3161-3165 (1988)