Nonstationary optical transfer functions of underwater imaging systems

Optical transfer functions of underwater imaging systems employing narrow pulses or sinusoidally modulated beams for image formation are studied. A modified Monte Carlo technique allowing for direct statistical modeling of these functions accounting for temporal dispersion is proposed and implemented. The optical transfer functions are calculated for various modulation frequencies of the illumination beam and for the case of pulsed illumination. The employment of high-frequency sinusoidal or pulsed modulation with consistent processing of the received signal is shown to significantly increase the contrast sensitivity of underwater imaging systems as compared with systems with stationary illumination.