D.J. Agdeppa was born in the Philippines and moved to Maui during the summer of 1998. She graduated from H.P. Baldwin High School in 2006 and later decided to enroll in UH Maui College. D.J. is majoring in Electronics and Computer Engineering Technology and plans to graduate with an associate degree in 2012.
Home Island: Maui
High School: H.P. Baldwin High School
Institute when accepted: UH Maui
Improving the Uniformity of Thin-Film Coatings for Optical Mirrors
Project Site: Univ. of Hawai’i Institute for Astronomy
Mentor: J.D. Armstrong & Jeffrey Kuhn
The Institute for Astronomy (IfA) facility on Maui houses a vacuum chamber capable of coating substrates up to a half-meter in diameter with thin films of aluminum or other substances. In thin-film deposition, the pre-coating and coating processes both contribute to obtaining a high-quality result with a uniformity of coverage similar to that of commercial-grade mirrors. However,
samples coated in the IfA vacuum chamber were observed to have a number of imperfections, including scratches, pits, and tiny pinholes. Therefore, a series of experiments were conducted in order to find the most effective techniques for preparing and coating future telescope mirror substrates. Both electron-beam (“e-beam”) and thermal evaporation methods were used to vaporize aluminum and produce thin-film coatings on a series of flat glass substrates. Microscopy was used to image both the uncoated substrates and the coated end-products in an effort to trace the source of the imperfections. Ultimately, the following factors
were found to play a part in eliminating defects in the final mirror coating: polishing the substrate, modifying the cleaning method, and implementing a “clean room” near the coating lab. A polished substrate and/or a different method for cleaning provides a smoother initial surface to be coated, while the use of a clean room near the coating lab decreases the chance that the substrate will be contaminated with particles. As long as the pre-coated surface of a substrate remains smooth and free of contaminants, the result should be a decreased number of defects.