Examine the Rainbow Peephole in the middle of the cardboard disc. If you look very closely, you can see that there are tiny “scratches.” Light is actually made of colors, and these scratched lenses work in a way that refracts (bends) and separates these colors. The lenses are made out of a material called diffraction grating – a special material that bends and separates light into the colors of the spectrum.
These Rainbow Peepholes work in much the same fashion as a bunch of raindrops falling from the sky. As the raindrops fall, they refract the light from the sun into the beautiful rainbow phenomenon we see at the end of a rainstorm. You might ask why objects that don’t give off light have rainbows around them. That is because objects reflect light, which gives them color. You probably noticed that there was a pattern to the colors of the rainbow you observed while looking at the glasses – red, orange, yellow, green, blue, indigo and violet (this is called ROY G BIV order). The diffraction grating material breaks up the light and we observe them in ROY G BIV order.