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May, 2002 EEEL Expands UV Optical Material Characterization Facility to Include Laser Damage |
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EEEL's Optoelectronics Division has completed a series of measurements to determine the damage threshold and lifetime of optical materials under intense ultraviolet radiation (UV) produced by excimer lasers. Using a capability developed by EEEL scientist Richard Jones and Holger Laabs, a guest researcher, the integrated energy density (or dose) necessary to cause catastrophic damage of selected UV materials was determined using a beam profile technique similar to that described in ISO 11254-2. These studies, part of an on-going program to develop a primary standard for 157 nm excimer laser power and energy measurements, represent the first quantitative damage studies of UV optical materials for use with excimer lasers. Long-term exposure studies were carried out in cooperation with MIT Lincoln Laboratory to simulate typical calorimeter operating conditions. The damage measurements were performed using a beamsplitter-based calibration system in which a spatially uniform beam from an ArF excimer laser is generated using a special beam homogenizer. The beam profiles were recorded and characterized to determine the integrated dose at the sample plane. Measurement traceability for these measurements stems from an electrically calibrated, primary standard calorimeter developed by EEEL scientists Chris Cromer and Marla Dowell. Contact:
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