Mirage

In OPTI-GONE Int.'s contraption Mirage, two concave mirrors are placed one on top of the other, with a small opening at the top of one. This contraption forms a floating image inside this opening using the mirrored surfaces inside. After much consideration and learning about concave mirrors, the answer to why this works seems to lie in the focal legnth of the mirrors. When light enters the opening, it hits the object on the bottom, reflecting off the object and radiating out into the mirror region. In the cases of light rays like the ones diagramed, they will bouce a few times, hitting a mirror and refracting at the same angle of incidence, continuing until it either happens to exit the region, perhaps without even touching the object, or hitting the bottom mirror parallel to the principle axis. When it does, the light will then refract to the focal point, which for these mirrors is placed either inside the opening for the bottom mirror or at the center of the bottom mirror for the top mirror. This results in the fact that nearly all light will eventually converge on the focal point at the opening, creating an image to the human eye that should originate in what is actually thin air. The fact that the object sits on a mirror also results in an image of the image of the object on the bottom mirror appearing at the opening as well. Pretty cool!