The Polaroid-Land Effect

In the 1960's a friend of mine and I were interested in entering our high school science fair and he happened to also be interested in photography. He had his own darkroom and some pretty good cameras. He had read about an interesting effect where you could take two pictures in black and white of exactly the same object, one using a specific red filter and the other using a specific green filter. Both pictures would be processed into a 35 mm slide in "black and white". These two pictures would then be later projected on a screen in exactly the same location. Another method of merging these two black and white pictures that could be used was to project one on the back side of a special mirror and the other black and white picture would be projected on the front side of the mirror. The mirror had to have a degree of transmission through the mirror making it similar to a two way mirror.

When the two black and white pictures were merged they would display the merged picture in "full" color. This was reported in Edwin H. Land, "Experiments in Color Vision," Scientific American, Vol. 200, No. 5, pp. 84-99, May 1959. I believe it was in this issue that we read about a location in New Jersey or New York City where this special mirror could be purchased. I remember getting on a bus and traveling there and I remember that we definitely felt uneasy about the area of the city where we were supposed to find this small company.

I am not going to try to explain this effect, but merely relate a personal story about our curiosity and experiences in our youth with this effect. Other professionals can explain this effect far better than me. It points out how children can get excited about science.

When we finally found the correct address, it was in an upstairs location in a run down building. When we went into the office it looked a bit like a lab that you might find in an old science fiction movie, with large glass bell jars and large electronic switches around the lab. This was not like modern looking labs of today. An old man greeted us and we told him what we wanted and he quickly produced the mirror and we were on our way. We did get a little tutorial about how such mirrors were made at that time, which was the evaporation of metallic materials onto the back surface of the glass.

We were really glad to get out of the place and out of that part of town and on our way home. At home we still needed to get the filters, but these could be obtained from most photography stores and if necessary could be ordered. The mirror might not have arrived in time for us to use it for the science fair project. This was his science fair project, so I only provided general support, besides I really didn't know any photography.

He made the project and it did work, although not as well as we might have liked. We would have preferred to used two slide projectors, but the mirror was our second choice. We did not have a chance to try some different experiments, just barely getting the project accomplished. About this time a lot of experimentation was being conducted on visual affects and color. Spinning wheels with black and white designs can cause the brain to see color effects where there is no color. This has to do with the distance between the black and white designs, the movement of the designs and many characteristics in our vision and brain.

Black and white television briefly experimented with a flicker of the black and white spots to stimulate the production of color perception. Although this method also does work somewhat it could not compete with other methods being developed. For a short time it was thought that the visual pixels on color television might be oscillated to "enhance" colors, but this never became a reality either.

It would be interesting now to look back at these experiments and see if we could still learn more about vision, color, and our brain.