ype is the Cyberscope available from Simsalabim. Head Mounted Display (HMD)One hardware device closely associated with VR is the Head Mounted Device (HMD). These use some sort of helmet or goggles to place small video displays in front of each eye, with special optics to focus and stretch the perceived field of view. Most HMDs use two displays and can provide stereoscopic imaging. Others use a single larger display to provide higher resolution, but without the stereoscopic vision. Most lower cost HMDs ($3000-10,000 range) use LCD displays, while others use small CRTs, such as those found in camcorders. The more expensive HMDs use special CRTs mounted along side the head or optical fibers to pipe the images from non-head mounted displays, ($60,000 and up). A HMD requires a position tracker in addition to the helmet. Alternatively, the display can be mounted on an armature for support and tracking (a Boom display). Health Hazards from Stereoscopic DisplaysThere was an article supplement with CyberEdge Journal issue #17 entitled "What's Wrong with your Head Mounted Display". It is a summary report on the findings of a study done by the Edinburgh Virtual Environment Lab, Dept. of Psychology, Univ. of Edinburgh on the eye strain effects of stereoscopic Head Mounted Displays. There have been a number of anecdotal reports of stress with HMDs and other stereoscopic displays, but few, if any, good clinical studies. This study was done very carefully and the results are a cause for some concern. The basic test was to put 20 young adults on a stationary bicycle and let them cycle around a virtual rural road setting using a HMD (VPL LX EyePhone and a second HMD LEEP optic equipped system). After 10 minutes of light exercise, the subjects were tested... "The results were alarming: measures of distance vision, binocular fusion and convergence displayed clear signs of binocular stress in a significant number of the subjects. Over half the subjects als...
