The University of St. Thomas

Optics

Optics

Most of our research involves optical polarization. Polarization describes the vector nature of light—the direction in which a light wave vibrates. It adds a tremendous amount of information about light-matter interactions that is not provided by the more common measurements of wavelength and intensity. Most light is at least partially polarized, and this polarization usually changes when light undergoes scattering, reflection, or transmission. Polarimeters are used to quantify these changes, and they are the primary instruments used in our research.

Our undergraduate students use polarized light in applications that are relevant to fundamental physics, biology, medicine, chemistry, geology, environmental sensing, and engineering. Some of our recent projects include

•      polarimetric and spectral analysis of butterfly wings and
       scarab beetle exocuticles

•      angular momentum transfer in optical tweezers using
       circularly polarized light

•      astronomical and environmental Stokes vector imaging

•      polarimetry of turbid and chiral media

•      image enhancement of simulated skin lesions with polarized
       light

•      studies of optical depolarization

•      Mueller matrix characterization of commonly used optical
       elements

•      construction of simple, inexpensive versions of optical
       instruments to make them more accessible to small physics
       departments (e.g., photoelastic modulators, Stokes and
       Mueller-matrix polarimeters)

More information about a few of these projects can be found in the student-made posters on the right side of this page.

At the core of our research are several professional-quality polarimeters and other optical instruments, many of which are highlighted in the pages of this pdf:

We gratefully acknowledge the National Science Foundation, the 3M Company, the Imation Corporation, Axometrics, Inc., and the University of St. Thomas for funding, equipment donations, and/or generous educational discounts in purchasing.

Student Posters and Videos
Video: 6-micron Sphere Trapped & Dragged by Optical Tweezers


Video: Micron-sized Calcite Crystal Spinning in Circularly Polarized Optical Tweezers


Optical Trapping and Manipulation of Micron-sized Particles and Bacteria


Survey of Circularly Polarized Beetles


Optical
Polarimetry
of Butterflies
and Beetles


A Hydrocolloid-
based Photoelastic Modulator

Stock Sheets of Polycarbonate as Inexpensive Low-order Optical Wave Plates

Biological
Applications of Spectral Polarization-
Difference Imaging

Polarimetric Characterirzation of Materials