The strength in Pepper's ghost illusions is that through careful graphics, projection optics, lighting and props they are able to provide good monocular depth cues --and because you are looking through the half-silvered
mirror to the virtual image beyond, the viewer cannot get close to the projected image.
Most people don't have access to the half-silvered
mirrors TV Studios employ.
It was derived from an instrument invented in 1731 that used two mirrors to project the image of stars, the sun or the moon onto a half-silvered
mirror through which the navigator could see the horizon.
The best bed was embroidered and 'half-silvered
' and at the time, valued at pounds 5.6s.8d.
"Within the visor are placed half-silvered
optical surfaces, one in front of each eye.
The Maryland experiment and one of the Garching experiments involve Mach-Zehnder interferometers, devices that take an incoming light pulse from a laser, split it in two with a half-silvered
mirror, send the two halves over different paths and recombine them.