TRANSFER-FUNCTION OF SPATIAL-FREQUENCIES IN PARAMETRIC IMAGE AMPLIFICATION - EXPERIMENTAL-ANALYSIS AND APPLICATION TO PICOSECOND SPATIAL-FILTERING

We recently performed the parametric amplification of a monochromatic near-infrared image, in a KTP crystal with a resolution of 60 X 80 poi nts and a gain of 15 dB. In this paper, we directly measure the transf er function of spatial frequencies by recording the image Fourier plan e. This analysis confirms the link between the phase-matching conditio ns and the resolution. Moreover, parametric amplification can act eith er as a low pass filter or as a band-pass filter, depending of the ori entation of the crystal. Consequently, basic image processing operatio n can be performed.