Can fluorescence and SHG data be enriched by Müller matrix signature

Description

The most recent advances in optical microscopy are mainly focused towards superresolution, using fluorescence stochastic/targeted read-out methods [1]. Since the demand is growing for imaging thick biological specimens as cell aggregates (i.e., tumor spheroids), tissues/organs (i.e. ligaments, meniscus) and small organisms (i.e. zebrafish), scattering represents a key aspect in image analysis and reconstruction [2]. Additional information, if exploited correctly, improves the accuracy of any measurements giving rise, in the specific case of optical microscopy, to an increase in the bandwidth and hence resolution of the system [3]. So far, polarization properties of the incoming/outcoming light have been shown to be able to provide further information about the sample [4, 5]. Here the attention is given to the possibility of utilizing a Mueller matrix analysis of the signal in order to extract information about optically active biological structures in the sample, with particular interest in chiral objects [6-8]. Since Mueller matrix analysis is generally used to study polarization properties in angular scattering, an ongoing question is: can fluorescence and SHG data be enriched by Mueller matrix signature, too? As the possibility was demonstrated of obtaining ultrastructural information about chromatin-DNA organization using circular intensity differential light scattering [9], the Mueller matrix integrated approach could allow progress towards label free imaging. A possible Mueller matrix polarimetry integrated architecture will be outlined, based on photoelastic modulation (vs. Pockels cell) as a polarization generator along the excitation pathway [9-13]. A classical electrodynamics model will be reported about circular intensity differential scattering of chromatin-DNA in a label-free perspective [14]. In addition, some preliminary raw data arising from SHG measurements will be discussed.

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