Dynamic Diffraction Analysis

Pages written by Michael Lueckheide ’13

Dynamic Diffraction Analysis

The dynamic diffraction analysis began as a project to determine whether a three-dimensional technique using laser light to study biological systems could be an inexpensive and accurate alternative to microscopy.  The diffraction patterns created by a laser beam traveling through an optical cuvette of C. elegans can be used to study the movement and position of the worms as the pass through the beam of light.

Initial Diffraction Data Collection Set-Up

Initially video data of the diffraction patterns of the worms was taken.  Matlab was used to model the possible orientations of the worms and the fast Fourier Transform of the model worms resulted in a modeled diffraction pattern that could be compared to the raw video data.

Matlab Modeled Worm Orientation and Resulting Diffraction Image
Actual Image of a Diffraction Pattern taken from the Video Data

Next  more control was exerted over how much space the worms had to move by using 1mm, 2mm, and 5mm cuvettes.  The density of worms in the cuvettes was also controlled and more video data was taken.  This video data was analyzed using logger pro and the average thrashing frequency and standard deviation was determined for each cuvette.

Example of a Logger Pro graph of angular frequency vs. time

The logger pro method was fairly time intensive, so an automated technique using a oscilloscope connected the the computer was developed to allow for a faster analysis and determination of thrashing frequency.  The automated technique also appears to reveal information about the worm shape as it is moving through the laser beam.

Diffraction Pattern Waveform taken from the Oscilloscope Data

Based on initial frequency values it would appear the thrashing frequency of C. elegans is affected by how constrained their motion is, meaning whether they are crawling, slipping/sliding, or actually swimming.

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