Imaging through scattering media with wide spectral illumination

Speckle autocorrelation based on optical memory effect is an interesting and important method to realize scattering imaging. However, the effective detection range is limited by the radiation phenomenon of the speckle field when there is a wide spectral illumination. In this paper, by utilizing the response of point spread function (PSF) to image distance (the distance between the detector plane and the scattering medium), we propose a method to improve the imaging quality under wide spectral illumination. PSF is sensitive to the image distance, as the distance between the detection plane and reference plane increases, the correlation coefficient between their PSFs will decreases. Superposing the autocorrelations of speckle patterns under different image distances can suppress the statistical noise, and thus improve the reconstruction quality. This method reduces the dependence on light source power and effective detection range, having certain prospect in seeing through natural turbid media.