|
Optical scattering properties are important diagnostic indicators with sensitivity to sub-resolution tissue structure as well as being necessary parameters for modeling light transport. Improved understanding of scattering in tissue is essential for optimizing and interpreting image contrast, modeling optogenetics, and developing next-generation optical imaging approaches. Despite the importance of optical scattering properties, most measurement methods rely on approximations or assumptions about the shape of the angular distribution of scattered light (phase function) or lack the spatial resolution to characterize heterogeneous tissue. There is a need for a spatially resolved method to quantify the optical scattering properties including the shape of the phase function.
This work presents a lens-based spectral goniometry system and spatially resolved measurement of 4pi optical scattering phase functions. Angle-space measurement of scattering is performed by imaging the Fourier plane of a high-NA microscope objective. By combining forward and backward images and varying the illumination beam angle, the entire 4pi phase function can be acquired. This method enables several capabilities: a) Spatially resolved measurement of properties combined with stage scanning provides mapping of layered or heterogeneous tissues with <100 micron sampling. b) By inverting the angular scattering measurements, this approach allows characterization of refractive index autocorrelation. c) As a camera and lens based measurement technique that collects large solid-angles of scattering in a single image, the non-axially symmetric scattering signature of fibrous or oriented tissue can be characterized. These applications as well as instrument design and analysis methodology will be presented.
|
