Tomographic Mueller Polarimetric Microscope

This home-built free space setup aims at measuring the polarizance of the sample in 3D. To do so, it performs multiple Mueller polarimetric acquisition (see setup Mueller Polarimetric Microscope) at different view of the sample in a tomographic fashion, i.e. at different tilts and rotation of the sample. Due to the use of visible light, the sample need to be thin enough to be always in focus and is therefore often milled into a small cylinder shape (~200 um). To remove unwanted edge scattering and lens effect, the sample is immersed in matching index liquid. Using a gradient based iterative algorithm, one can retrieve from those measurements the 3D birefringence properties of the sample, in its full volume. See https://doi.org/10.1002/advs.202502075

Schematic of the Tomographic Mueller Polarimetric Microscopy setup.
Schematic of the Tomographic Mueller Polarimetric Microscopy setup. LP stand for Linear Polarizer, HWP for Half Wave Plate and QWP for Quarter Wave Plate. PSA and PSG are respectively Polarization State Generator and Polarization state Analyzer.
© Paul Scherrer Institute / Arthur Baroni
Close-up picture of the Tomographic Mueller Polarimetric Microscopy setup.
Close-up picture of the Tomographic Mueller Polarimetric Microscopy setup.
© Paul Scherrer Institute / Arthur Baroni
Example of results of TMPM
Reconstructed 3D optical anisotropy of trabecular bone. (A) A microscope image of the bone sample immersed in oil under a lateral illumination (10x, 0.28 NA). (B) Reconstructed tomogram of the absorption A. (C) Reconstructed index ellipsoid in each voxel of the volume by TMPM. Both the ellipsoid length and the color gradient indicate the strength of birefringence Δn, orienting its c-axis. (D and E) Other views of the reconstructed index ellipsoids, plotted as cylinders to highlight their c-axis orientation, with a length proportional to the birefringence Δn, color coded with (D) birefringence Δn and (E) c-axis angle (ϕ,ψ) where ψ is encoded on hue and ϕ in scale of the color value and saturation. Inset shows zoom-in of the same region at two different views, outlining the c-axis orientation. [https://doi.org/10.1002/advs.202502075]
© Paul Scherrer Institute / Arthur Baroni & Yang Chen

Dr. Arthur Baroni
Structure and Mechanics of Advanced Materials, Center for Photon Science
Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
Telephone: +41 56 40 44,  e-mail: arthur.baroni@psi.ch

Dr. Marianne Liebi
Structure and Mechanics of Advanced Materials, Center for Photon Science
Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
Telephone: +41 56 310 44 38, e-mail: marianne.liebi@psi.ch