Richard L. Axelbaum, Ph.D., associate professor of mechanical engineering, demonstrates a model of his device at his synagogue, Young Israel of St. Louis. The device creates an optical illusion permitting one-way viewing through a wall separating men and women in Orthodox Jewish worship. In Orthodox Judaism, men and women are required to worship apart and are separated by a partition called a mechitza. According to Orthodox Jewish law, there are no restrictions on women looking over to the men's side. People have tried traditional see-through mirrors to solve the problem, but they found that design actually creates two other problems.
Darkness obviously hinders a worshipper's reading ability.
Axelbaum created a modification of a see-through mirror to remedy the situation. Taking the standard design of such a mirror, angling it at 45 degrees and incorporating it into an assembly that resembles horizontal window blinds, he painted the panel above the mirror black and put a wallpaper design on the panel below the mirror. On the women's side, light reflecting off the black panel and bouncing off the mirror back to a person's eyes reflects the darkness. The image is practically unnoticeable and lets women see through. However, on the men's side, the light reflects the brightly colored wallpaper and nothing else, so what the men see is a wallpaper design.