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P H O T O G R A P H Y C O N T E S T Sponsored by A.J. Hirsch |
David Nolan
Honorable Mention
2005 OAPT 4U Photo Contest
Analyzing Stress Patterns in a Lucite Model
When the tape dispenser is placed between a polarizing filter and an analyzing filter, the stress patterns in the Lucite become visible. When photoelastic materials, such as Lucite, are placed under stress it causes the molecules in the material to align which in turn causes it to on double refractive properties. The plane of the polarized light will be rotated when reflected off of the tape dispenser. The varying areas of stress mean that the amount of refraction in the tape dispenser varies. As the refraction changes, the speed of propagation also changes, which means that light reaching the analyzing filter will be polarized in different planes forming a pattern which highlights the areas of stress. As the analyzing filter is rotated, it polarizes the light differently resulting in a change of pattern/color in the model.