This fall, Shaun Koide will enter his junior year in Electrical Engineering at the California Polytechnic State University in San Luis Obispo, California.  His academic interests include digital and radio-frequency aspects of electrical engineering, and he is considering a career in RF communications.  Shaun is an active member of his college’s amateur radio club, where he participates in nationwide communications contests, volunteers in community events, and helps to conduct amateur radio licensing sessions.  He also enjoys going on adventures, hiking, photography, drawing, playing video games, keeping up with local, world, and technology-related news, and spending quality time with his family and friends.

Institution when accepted: California Polytechnic State University, San Luis Obispo

Akamai Project: AO System Deformable Mirror
Project Site: Subaru Telescope
Mentor: Stephen Colley

Project Abstract:

The 188 high-voltage signals controlling the curvature of Subaru Telescope’s adaptive optics (AO) deformable mirror must have a slew rate no greater than 100 V/ms, as specified the manufacturer.  If the slew rate of a signal is higher than the specified value, the mirror is at risk of fracturing or other damage.  To limit the slew rate, the digital signals controlling the voltage outputs of 188 DACs need to be monitored.  When needed, the data steam will be modified so there are no drastic changes over time.  The smaller steps approximate ramping signals on the analog outputs of the DACs, which allow for slower surface-shape transitions on the deformable mirror.  To do this, we have designed a digital logic system in VHDL, using Altera Quartus II software.  This logic will be programmed onto the existing FPGAs on 5 rack-mounted boards, which are already in the system.  The logic compares each of the 188 digital inputs from the real-time control computer to the previous signals sent to the DACs.  The modified digital signals create a ramp between the two points with a 100-V/ms slew rate.  Because the necessary hardware already exists, this provides a relatively simple and inexpensive safeguard for a complex and extremely expensive piece of astronomical equipment.