Here is a demonstration of a mirascope:
The physics of the mirascope is fairly simple and yet the resulting 3D ghostly image seems simply magical. The mirascope consists of two parabolic mirrors facing each other in a clamshell fashion. The key to the design is that the focal point of each parabolic mirror sits at the vertex of the other, and a hole is made in the top mirror's vertex where the image is produced. To understand how reflection of light can create such an image, consider the special geometry of a parabola. A ray diagram illustrates how parallel rays of light that reflect off a parabolic curve will all meet at its focus (figure 1). This is the operating principle of satellite dishes or any parabolic reflector. It of course works in reverse: a light source located at the focus will reflect off the curve and leave the dish as parallel rays, a phenomena used by microwave communication antennas and searchlight reflectors.
|figure 1: Parallel rays reflect and converge at the focal point F |
|figure 2: Diagram included on the packaging |
of the Opti-Gone Mirage
Get one here!
The larger version (Diameter = 9 in) as seen in the above video:
From Educational Innovations: BUY NOW "Mirage" Mirascope
From Amazon: BUY NOW "Mirage" Mirascope
A smaller version (Diameter = 6 in) that works well too:
plastic frog included =)
From Educational Innovations: BUY NOW Small Mirascope
From Amazon: BUY NOW Small Mirascope