The technical definition of birefringence has to do with a material possessing a refractive index varying with the propagation direction and polarization of light. This often leads to light refracting twice before you see it.
In terms of photography, birefringence involves using a polarized filter to take a picture of clear plastic that is already under polarized light. The result is photographs that show a liquid combination of colors instead of the normal clarity of light.
Birefringence photography basically involves the use of two polarizing filters: one between the subject and the light source, to polarize the light, and a second on the lens of the camera.
The first filter should ideally be linear, but the one on the camera can either be circular or linear. Polarized light sources are easy to find, because most LCD television screens and computer monitors already feature linear polarization. If you really would rather not use a screen or don’t want those RGB pixels, just try a light table that has polarizing paper sitting on top instead. If you don’t have a polarizing lens filter, you can use a polarized sun glass instead.
Here are some tips to get the best results from birefringence photography.
Providing back-lighting to the subject gives the photo-elasticity (the liquid look to the colors) the best effect. If you use a computer screen, make sure that it is pure white. The easiest way to get this is to open Paint or Notepad, and make the program full screen. Adjust the brightness as necessary.
Then, put the polarizing filter onto the lens. Turn it around to see how the appearance of the subject changes. If your camera has the “Live View” option, this is much easier to manage. Check out the LCD screen, and when the subject looks like you want it, take your picture.
If you want a stronger effect, apply more than one plastic layer.To make a hip, retro image of a cassette tape that would make a fun 80s party image for an Evite, set the cassette against the all-white monitor screen. When the polarizing filter is on your camera, you can see the swirling bands of color on the clear surface of the cassette.
After you take the picture, you can edit the background from white to the color of your choosing. Going with black allows the bright colors of your cassette to stand out with the most contrast.
You will wow the people on your invite list with your photographic wizardry!