This is one of those "just in time" articles, luckily with a good beer and a fine piece of belgian soft cheese. Kanpai!
Above: my pond, without a polarization filter. Below: the same pond with a polarization filter
Two polarized Colors models with a Geometric model in the middle.
Another application of polarizing filters in in the 3D glasses in the cinema. The 3D movie is projected with two opposite directions orientated polarized light. Now the glasses have a 90º rotated orientation, so you only can see one projection per eye, and each eye sees another projection.
Also the LCD of a digital watch uses a polarization filter. Liquid crystal is a special substance, often cholesterol derivates, which has both crystal as liquid properties. By applying an electric current on a liquid crystal, the crystal will form a line pattern in molecular scale. It will only allow to pass light in one polarized direction. If the current is applied under 90º, it will block all light in the same polarized direction. Microscopic fine electrodes are connected to an LCD screen, turning on and off the digits.
Polarization filters are also often used in photography. It helps reducing annoying reflections, but also brings more contrasts in clouds. It also can give a nice color to the blue sky. When you use a polarize filter to take photo’s of a digital watch, like most G-Shocks, it’s possible to completely black out a digital display. Luckily for people wearing sunglasses with polarized lenses, the orientation of an LCD display seems also vertical. This means you can always check your watch with your glasses on.
Let’s take a closer look to this nice yellow Polarized Colors version. The color used for the resin on this watch is not the regular “Positive Yellow”, but a lighter color, that is shifted also a little more to green. I guess this color is close to lemon yellow. It has a high glossy finish. On the inside of the strap you can see the base color. It is almost signal yellow. While the face plate is polarized blue. This is achieved by etching a vertical line grating. It acts like diffraction grating used on monochromators (in photo spectrometry). A similar effect is achieved by looking at the information side of a CD from a low angle. Sometimes it looks dark blue, almost black, sometimes it looks bright metallic blue. The main display is grass green. The background reflector seems dark green, which sometimes looks like a mirror. The eyes however are orange. The EL backlight of the main display looks quite nice in bright green. The eyes lit up a kind of amber.