2018 BFY III Abstract Detail Page
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||A Senior Level Lab Demonstrating the Utility of AFM
||An experiment for our senior level laboratory course was developed to elucidate the utility of AFM in measuring the 3rd dimension. Using a laser, students measure the interference pattern of a diffraction grating to determine the groove spacing in the normal way. They then use an AFM to image the grooves directly to verify this spacing, but also to reveal a second property of the grating, the blaze angle, an important grating feature, used to shift the center of the diffraction envelope to a first-order interference maximum. In the second part of the experiment, a laser is again used to produce a diffraction pattern, but this time from reflections off a compact disc (CD). The origin of this pattern is ascertained when students use the AFM to reveal rows of bumps on the CD surface. The AFM also measures the bump height, exposing the mechanism of CD operation, the destructive interference of light. For both the diffraction grating and CD experiments, student results yield calculated parameters (e. g. indexes of refraction) that are typically within 10% of stated values from the manufacturer. Funding was provided by the National Science Foundation Nanotechnology Undergraduate Education program, award # 0406533.
California State Polytechnic University
Pomona, CA 91768
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