Optics

Polarized Light Imaging

Our undergraduate students have built a polarimetric imaging device that has a multitude of applications.  It can potentially be used for the detection of skin cancer, for robot navigation, to enhance vision for underwater exploration, and to help us understand how certain animals navigate and communicate with polarized light. This device incorporates linear polarizers, quarter-wave plates, interference filters, and CCD cameras.  It measures complete Stokes vectors of a scene and can be adapted to visible, near infrared, and near ultraviolet spectra.
 

Mueller Matrix Polarimetry

A Mueller matrix represents how an optical target affects the polarization states of incident light, and a Mueller matrix polarimeter is a device that measures such a matrix. It allows us to investigate a material’s optical asymmetries in terms of the following important parameters: retardance, diattenuation, polarizance, and depolarization.  In our laboratory, students have constructed a relatively inexpensive, automated polarimeter that can be employed in experiments with applications to physics, engineering, biology, geology, and chemistry. This device comprises liquid crystal optics and other high-quality polarizing components. Students have written LabVIEW software that controls the apparatus and calculates the polarization properties of nearly any target that we place in the system. Our homemade device accompanies a more sophisticated Mueller matrix polarimeter manufactured by Axometrics, Inc. (see www.axometrics.com). With these two devices, we are well-equipped to thoroughly analyze numerous interesting samples.

The posters on the right display examples of our recent polarimetry experiments.  In addition to these physics and engineering projects, we are conducting a survey of scarab beetles that reflect circularly polarized light—a rare phenomenon in nature.  (See the poster “Optical Polarimetry of Butterflies and Beetles” for more information.)  Here are the results of our survey thus far: Circularly Polarized Scarab Beetle Database.  Does the phenomenon have a biological function?  Can the beetles or other animals see circular polarization?  Is there a correlation between circular polarization and habitat?  How about predator-prey relationships?  We don’t know the answers yet.

Dr. Adam Green's publications since the fall of 2003

(boldface indicates undergraduate student)

A. S. Green, P. R. Ohmann, N. E. Leininger, and J. A. Kavanaugh “Polarization Imaging and Insect Vision,” accepted for publication, The Physics Teacher, November 2008. (to appear in the spring of 2009)

K. J. Braun, C. R. Lytle, J. A. Kavanaugh, J. A. Thielen, and A. S. Green, “A Simple, Inexpensive Photoelastic Modulator,” accepted for publication, American Journal of Physics, August 2008. (to appear in January 2009)

P. R. Ohmann, A. S. Green, and M. E. Johnston, “Infusing Computation throughout the Undergraduate Curriculum,” Computers in Education Journal, Vol. XVIII (3), July-September 2008.
 
T. J. Gay, J. Bozek, J. E. Furst, D. Kilcoyne, G. A. Gallup, A. S. Green, A. L. D. Kilcoyne, J. Machacek, J. W. Maseberg, K. W. McLaughlin, and M. A. Rosenberry, “Angular Momentum Partitioning in the Dissociation of Diatomic Molecules,” in Ionization, Correlation, and Polarization in Atomic Collisions, edited by A. Lahmam-Bennani and B. Lohmann, American Institute of Physics 811 (1), 108 (2006).

A. S. Green, G. A. Gallup, M. A. Rosenberry, and T. J. Gay, “Spin-Exchange-Induced Circularly Polarized Molecular Fluorescence,” Physical Review Letters 92 (2004).

Grants since the fall of 2003

Title: “An Undergraduate Optics Laboratory with a Biomedical Emphasis”
Granting Agency: National Science Foundation (DUE-0509869)
Grant Amount: $123,323, including $34,740 match from UST
Award Dates: 09/01/05 – 08/31/08
Principal Investigator: Adam Green

Title: “Incorporating Computer Modeling into the Upper-Division Physics Curriculum”
Granting Agency: National Science Foundation (DUE-0311432)
Grant Amount: $122,322, including $25,500 match from UST
Award Dates: 08/15/03 – 07/31/06
Principal Investigator: Paul Ohmann
Co-Principal Investigator: Adam Green

Title: “Support of Undergraduate Research in Physics and Geology”
Granting Agency: Minnesota Space Grant Consortium
Grant Amount: $332,528, including $162,593 match from UST
Award Dates: 04/01/04 – 03/31/09
Principal Investigator: Marty Johnston
Participating Investigators: Adam Green, Tom Hickson, Jeff Jalkio, Lisa Lamb, Paul Ohmann, Marie Lopez del Puerto, Gerry Ruch, Kevin Theissen

Title: “Reflective Polarizing Structures of Papilio Butterflies”
Granting Agency: Bush Foundation Program at the University of St. Thomas (Young Scholars Grant)
Grant Amount: $4000 for student researcher and $500 for faculty supervisor
Award Dates: Summer 2007
Student Investigator: James Kavanaugh (he wrote the application)
Faculty Supervisor: Adam Green

Title: “Continuing to Enhance a Research Community in the UST Physics
Department”
Granting Agency: Bush Foundation Program at the University of St. Thomas
Grant Amount: $964
Award Dates: Summer 2005
Principal Investigator: Adam Green

Title: “Enhancing the Research Community in Physics at UST”
Granting Agency: Bush Foundation Program at the University of St. Thomas
Grant Amount: $870
Award Dates: Summer 2004
Principal Investigator: Adam Green

Presentations since the fall of 2003

B. Kirkwood and A. S. Green, “Innovative Practices in the Life Sciences Major,” as workshop co-leaders, 2008 NSF-CCLI Principal Investigators Conference, Washington, D.C. (August 2008).

A. S. Green, “An Undergraduate Optics Laboratory with a Biomedical Emphasis,” NSF-CCLI Principal Investigators Conference, Washington, D.C. (August 2008).

J. A. Kavanaugh and A. S. Green, “Stock Sheets of Polycarbonate as Inexpensive Low-order Optical Wave Plates,” Meeting of the American Physical Society, St. Louis, MO (April 2008)

K. J. Braun, C. R. Lytle, J. A. Kavanaugh, J. A. Thielen, A. S. Green, and M. E. Johnston, “A Hydrocolloid-based Photoelastic Modulator,” Meeting of the American Physical Society, St. Louis, MO (April 2008).

J. A. Thielen, J. A. Kavanaugh, K. J. Braun, and A.S. Green, “Polarimetric Characterization of Materials,” 3M Company Technical Poster Session, St. Paul, MN (August 2007).

P. R. Ohmann, M. E. Johnston, and A. S. Green, “Blending Internal and External Research Experiences for Undergraduates,” American Association of Physics Teachers Summer Meeting, Greensboro, NC (July 2007).

A. C. Urness and A. S. Green, “Polarized Light Imaging through Turbid Media,” American Association for the Advancement of Science, San Francisco, CA (February 2007).

P. R. Ohmann and A. S. Green, “Computational Modeling in the Upper-Division Physics Curriculum,” American Association of Physics Teachers Summer Meeting, Syracuse, NY (July 2006).

M. E. Johnston and A. S. Green, “Introducing Students to LabVIEW Without Tying up the Semester,” American Association of Physics Teachers Summer Meeting, Syracuse, NY (July 2006).

A. S. Green, P. R. Ohmann, A. C. Urness, M. J. Andreason, S. J. Reckinger, M. J. Behrns, and B. V. Petschel, “Biomedical and Biometric Imaging with Polarized Light,” American Association of Physics Teachers Summer Meeting, Syracuse, NY (July 2006).

P. R. Ohmann, A. S. Green,  M. J. Behrns, L. C. Edge, C. A. Micek, and A. C. Urness, “Incorporating Computer Modeling into the Upper-Division Physics Curriculum,” American Association of Physics Teachers Summer Meeting, Salt Lake City, Utah (August 2005).

T. J. Gay, J. Bozek, J. E. Furst, D. Kilcoyne, G. A. Gallup, A. S. Green, A. L. D. Kilcoyne, J. Machacek, J. W. Maseberg, K. W. McLaughlin, and M. A. Rosenberry, “Angular Momentum Partitioning in the Dissociation of Diatomic Molecules,” XXIV International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2005), Rosario, Argentina (July 2005)

A. S. Green, “Is Nature Ambidextrous? (The Physical Origin of Biological Homochirality)," Hamline University (November 2004).

P. R. Ohmann, M. J. Johnston, and A. S. Green, “A New Model: Collaborative Research at the University of St. Thomas Physics Department,” Council for Undergraduate Research Summer Conference, LaCrosse, WI (June 2004).

T. J. Gay, A. S. Green, G. A. Gallup, and M. A. Rosenberry, “Spin-Exchange-Induced Circularly-Polarized Molecular Fluorescence,” Division of Atomic, Molecular, and Optical Physics Meeting of the American Physical Society, Tuscon, AZ (May 2004).

J. Zohner, A. S. Green, and T. J. Gay, “The Reduction of Instrumental Helicity-Dependent Intensity Asymmetries in an Optical Train,” Division of Atomic, Molecular, and Optical Physics Meeting of the American Physical Society, Tuscon, AZ (May 2004).

A. S. Green, “Probing Nature’s Handedness with Polarized Photons and Electrons,” Minnesota Chapter of the Optical Society of America, University of Minnesota (March 2004).