I would like to be able to electrically switch between horizontal and vertical light polarization. This polarization filter is supposed to be portable attachment running on a battery in front of a DSLR camera lens thus the filter should have the size of ~3x3cm minimum to cover the whole view. Light transmission through the filter should be the same in both polarization stages and as high as possible (i.e. ideally close to 50%). I would also prefer not to use any mechanical components, such as rotating the filter with a motor, to enable fast switching.
While I was looking for a solution I realized that LCD screens use two cross polarized filters and liquid crystal layer in between the filters to control what light passes through the display by twist the polarization 90 degrees. So I would basically need something like the LCD screen (without the need for controlling individual pixels) without the other polarizing layer and that's also fully transparent in both stages (twister & untwisted).
Another thing I was thinking is if I could possibly repurpose 3D shutter glasses, but not quite sure if this would work.
Best Answer
In the simplest form just use two digital cameras, one with a vertical polarizer and one with a horizontal polarizer. Use a beam splitter if you need an exact duplicate image on both cameras. Then run both video signals to the inputs of an analog switch/multiplexor (or a reversed biased diode switch*) and then digitally select the needed polarity signal as the single output.
*https://www.google.com/search?q=diode+switch+for+RF&biw=1549&bih=730&tbm=isch&tbo=u&source=univ&sa=X&ved=0CCgQsARqFQoTCN2i6YGY88gCFYNZPgodb1AEkQ