Current developments in fold mirrors
ABSTRACT Fold mirrors are used routinely in simulation displays for reducing system footprints and overcoming projector orientation limits.  Aluminized polyethylene terephthalate polyester film mirrors, commonly called Mylar mirrors, have been the industry standard and worked well for decades.  However, as projectors have evolved from relatively low brightness, low resolution CRT projectors to high brightness, high resolution, single exit pupil fixed matrix projectors, artifacts in Mylar film mirrors are becoming more evident.  Commercially available first-surface glass fold mirrors can correct some of these image artifacts, but have their own limitations, including unique image issues such as flow lines which may require additional manufacturing efforts (grinding and polishing) to remove.  Choosing the right type of fold mirror for a simulator display requires evaluating customer specifications including flatness, surface quality, reflectivity, hardness and coating adhesion, as well as the ability to clean the mirror surface with minimal if any damage.  System considerations include image quality, mirror size, weight, safety issues, service life, and maintainability.  This paper will address these matters and provide guidance for selecting the appropriate fold mirror technology for a given set of requirements.

VITA Justin Knaplund is the Chief Engineer at FlightSafety International Displays in Austin, TX. Mr. Knaplund graduated from the U.S. Air Force Academy with a BS in Astronautical Engineering, served eight years in the US Air Force as a Pilot and Instructor Pilot in the F-4E Phantom before separating to pursue a Master’s of Science in Aerospace Engineering from the University of Texas in Austin. After a period of employment with the Advanced Programs Office at the NASA Johnson Space Center in Houston, he was hired by Glass Mountain Optics and became the Director of Engineering, responsible for developing the designs for their WAC windows, cross-cockpit collimated Mylar and glass mirror displays, and their direct view (WASP) systems. Glass Mountain was acquired by FlightSafety International in 2009, and Mr. Knaplund was promoted from Director of Engineering to Chief Engineer in 2012.