Head Mounted Displays (HMDs) have been utilized by the military for various applications since the 1980's. In the 1990's, this technology migrated to the consumer market. Most of these early systems suffered the major drawback that they were "look-at" versus "see through" systems, which prevented the user from seeing their environment. This reduced the utility of the devices and could potentially lead to safety issues. This presentation discusses the optical design of a novel see-through High Definition display device with a 40 degree field of view.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.