The key problems of optical transmission imaging of thick complex biological objects are strong diffusion (scattering)
and non-uniform intensity distribution of transmitted signal across the scanned area. These constraints essentially reduce
the spatial resolution and uniformity of the overall pattern. We report on implementation of a new approach of signal
detection scheme, which relies on synchronization of lock-in amplifier with a temporal step of laser beam discrete
scanning. This technique is favorable for preferential detection of abrupt spatial features, increase of contrast and
substantial reduction of overall non-uniformity of image brightness. On the other hand, the lock-in detection scheme,
being phase-sensitive, helps to some extent to enhance the contribution of least-deflected photons in the recorded signal
thus suppressing the diffusion component. We present the results of measurements showing efficiency of the proposed
scheme.
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