Secchi disk imaging model and its application in performanceevaluation of underwater laser imaging systems

The performance of an active underwater laser imaging system is not only determined by the parameters of the imaging system, but also affected by the optical properties of the water. In order to evaluate the performance of the active underwater laser imaging system, the relation among the Secchi depth and the optical properties (such as absorbing coefficient, scattering coefficient, and diffuse attenuation coefficient) of the water were investigated based on the Secchi depth imaging model. Moreover, the expression for the maximum detection depth of the underwater laser imaging system as a function of the Secchi depth was deduced. Experimental results show that the relative error between the theoretical value and the measured value of the maximum detection depth of the intensified charge-coupled device(ICCD) range gated underwater laser imaging system is less than 20%. The Secchi depth imaging model is useful for performance evaluation of the underwater laser imaging systems because that it can reflect the relationship of the detection capability of the active laser imaging system and the optical properties of the water.