Original Article

A polarization-sensitive light field imager for multi-channel angular spectroscopy of light scattering in biological tissues

Rongwen Lu, Qiuxiang Zhang, Yanan Zhi, Xincheng Yao


Background: Angular spectroscopy of light scattering can be used for quantitative analysis of cellular and subcellular properties, and thus promises a noninvasive methodology for in vivo assessment cellular integrity to complement in vitro histological examination. Spatial information is essential for accurate identification of localized abnormalities. However, conventional angular spectroscopy systems only provide single-channel measurement, which suffers from poor spatial resolution or requires time-consuming scanning over extended area. The purpose of this study was to develop a multi-channel angular spectroscopy for light field imaging in biological tissues.
Materials and methods: A microlens array (8×8) based light field imager for 64-channel angular spectroscopy was developed. A pair of crossed polarizers was employed for polarization-sensitive recording to enable quantitative measurement at high signal specificity and sensitivity. The polarization-sensitive light field imager enables rapid measurement of multiple sampling volumes simultaneously at 18 μm spatialresolution and 3° angular-resolution. Comparative light field imaging and electrophysiological examination of freshly isolated and physiologically deteriorated lobster leg nerves have been conducted.
Results: Two-dimensional polarization-sensitive scattering patterns of the fresh nerves were highly elliptical, while they gradually lost the ellipticity and became rotationally symmetric (i.e., circular) as the nerves physiologically deteriorated due to repeated electrical stimulations. Characterized parameters, i.e., the ellipticity and the scattering intensity, rendered spatially various characteristics such as different values and deteriorating rates.
Conclusions: The polarization-sensitive light field imager is able to provide multi-channel angular spectroscopy of light scattering with both spatial and angular resolutions. The light scattering properties of nerves are highly dependent on the orientation of nerves and their physiological status. Further development of polarization-sensitive multi-channel angular spectroscopy may promise a methodology for rapid and reliable identification of localized abnormalities in biological tissues.

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