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Graduate Student Seminar - 09/28/2012

"One Million Micromirrors to Characterize Photocathode Electron Emission"

by Blake Riddick

Friday, September 28, 2012 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility

Advisor:  Professor Patrick O'Shea

A key figure of merit for a photocathode is its quantum efficiency (QE) of converting incident photons into emitted electrons. Measured QE is an average over the total illuminated area. Locally varying contaminants, lattice defect density, and crystal face cause nonuniform current density. QE maps revealing this variation have previously been measured using cumbersome raster-scanning techniques. Here, we present a simple, high-resolution QE mapping technique using a digital micromirror device (DMD). The DMD is a commerical television and projector component and is thus mass-produced and relatively inexpensive. It consists of a megapixel array of mirrors, each 14 microns wide which can be individually rotated to one or two stable positions. A DMD used as a spatial mask, in conjunction with simple mirrors and lenses, allows selective illumination of a photocathode and permits fast, high-resolution in situ QE mapping.

For additional information about the IREAP Graduate Student Seminars, contact David Meichle.

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