The Chinese magic mirror is an ancient art that can be traced back to the Chinese Han dynasty (206 BC – 24 AD). The mirrors were made out of solid bronze. The front is a shiny polished surface and could be used as a mirror, while the back has a design cast in the bronze. When bright sunlight or other bright light reflects onto the mirror, the mirror seems to become transparent. If that light is reflected from the mirror towards a wall, the pattern on the back of the mirror is then projected onto the wall. Michael Berry has written a paper describing the optics and giving some photos.