Sharpness enhancement of transmission imaging of structural objects in thick scattering media

Abstract

One of the main problems in optical transmission imaging of various structures, particularly biological ones, which are located in a relatively homogeneous matrix, is strong scattering, due to which the image becomes blurred already at submillimeter thicknesses. We report the results of experimental studies on enhancement of image quality by implementing a lensless double-diaphragm collimating system in a point-by-point imaging configuration that allows the predominant detection of ballistic light. In our study, we used a planar absorbing model object and a 20 mm-thick stack of polytetrafluoroethylene (PTFE) plates forming a bulk scattering matrix. By placing the model object at different positions in the stack, we analyzed the image blur depending on the depth of the structure to be visualized. It is demonstrated that for the case of the wide detection angle, the best image quality is attained when the model object is located close to the light beam incidence plane, and worsens sharply as it moves deeper in the matrix. The collimating assembly has been shown to significantly improve and equalize the image resolution across the depth, with some blurring in the mid-way thickness area.

Speaker

Aram PAPOYAN
Institute for Physical Research
Armenia

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