Sometimes, someone’s trash is another’s treasure. When a box of mirrors originally destined to be manufactured into Polaroid’s SX70 cameras showed up on the Exploratorium’s doorstep, Bob made
Image Mosaic
out of them. When you stand in front of the frame of mirrors, you see yourself duplicated dozens of times, but each upside-down image is slightly different because each mirror “sees” you from a slightly different position.
Most people don’t think about taking light apart and assembling it again. At
Distilled Light
, white light is broken up with special filters that reflect one color and let through all the rest. A beam of white light becomes three beams of red, green and blue light. Using the same type of filters, the three colors are reassembled into a beam of white light again. If you block one of the seperated beams, say the blue beam, you can see that white light becomes yellow without its blue component. You can also insert a colored filter into the initial white beam and see what colors are let through.
There’s really no magic at work in the
Magic Wand
. A projector produces a real image in space. Waving the wand provides a surface for the image to reflect from, so the light can get into the viewer’s eye. Persistence of vision—the eye’s capacity to retain an image for a short period of time—lets the brain see the moving reflections from the stick as one whole picture. Other images in space can be found by waving the wand closer to or farther away from the projector, but only one image is in focus
Image Relay
Four lenses are arranged along an optical bench to provide the visitor with a variety of experiments. Lighted areas at each end with the four lenses spaced two focal lengths apart provide an optical relay that transmits images at one end to the other. The use of a “field” lens can be explored in this arrangement. Each lens may be tilted out of the optical path. A lens near one end can be moved along the bench for focusing images. A screen and a flip up light source on one end which contains red, white and blue lights, enable the visitor to experiment with chromatic aberration. A screen with an annular shaped aperture allows the visitor to experiment with spherical aberration.
