Application and Effect of Polarizers in the Field of Photography in China and Germany
Polarizing mirror effect
1. Add a polarizing mirror in front of the camera lens to eliminate reflections.
When shooting objects with smooth surfaces, such as glassware, water surfaces, display cabinets, painted surfaces, plastic surfaces, etc., flares or reflections often occur due to the polarization of light. Adding a polarizing mirror and appropriately rotating the polarizing mirror surface during shooting can block these polarized lights, thereby eliminating or reducing the reflection or bright spots on the surface of these smooth objects. To observe the effect of eliminating polarized light, rotate the mirror while observing through the viewfinder. When the reflection of the subject disappears, the mirror can be stopped from rotating.
2. Control the brightness of the sky during photography to make the blue sky darker.
Due to the presence of a large amount of polarized light in the blue sky, using a polarizer can adjust the brightness of the sky. After adding a polarizer, the blue sky becomes very dark, highlighting the white clouds in the blue sky. Polarizers are gray, so they can be used in both black and white and color photography.
3. Using a polarizing mirror to watch stereoscopic movies
When watching a stereoscopic movie, the audience needs to wear a special pair of glasses, which are a pair of polarizing plates with perpendicular vibration directions. Stereoscopic movies are films made by simultaneously capturing images of a scene from two different directions using two lenses, similar to the human eye. During the screening, two sets of films captured by two cameras are simultaneously projected through two projectors, so that these slightly different images overlap on the screen. At this point, if viewed directly with the eyes, the image is blurry. To see a stereoscopic movie, a polarizer needs to be installed in front of each projector, which acts as a polarizer. The light emitted from two projectors becomes polarized light after passing through a polarizer The polarization directions of the polarizing plates in front of the two projectors on the left and right are perpendicular to each other, so the polarization directions of the two polarized light beams produced are also perpendicular to each other. These two polarized light beams are projected onto the screen and reflected back to the audience without changing their direction When the audience uses the polarizing glasses mentioned above to watch, each eye only sees the corresponding polarized light image, that is, the left eye can only see the image reflected by the left camera, and the right eye can only see the image reflected by the right camera. This will create a three-dimensional feeling like watching directly. This is the principle of stereoscopic movies. Of course, the actual projection of a stereoscopic film involves using a single lens and alternately printing two sets of images on the same film, requiring a complex set of equipment. The propagation of light in crystals is closely related to polarization phenomena. Polarization phenomena can be used to understand the optical properties of crystals, manufacture optical devices for measurement, and provide technical means such as rock and mineral identification, optical elasticity, and laser modulation.
4. Physiological functions of organisms and polarized light
The human eye cannot distinguish the polarization state of light, but the eyes of some insects are very sensitive to polarization. For example, bees have five eyes, three monocular eyes, and two compound eyes, each containing 6300 small eyes. These small eyes can determine the direction of the sun based on its polarization, and then use the sun as a directional marker to determine the direction. Therefore, bees can accurately guide their peers to the flowers they find. For example, in the desert, people can get lost without a compass, but there is a type of ant that can use the polarized ultraviolet light in the sky to navigate, so it will not get lost.
5. Use polarizing film in cars to prevent glare from oncoming lights at night
High beam headlights are very annoying, but using the polarization of light can solve this problem. We can design the car lampshade to be angled at 45 degrees; The polarizing lens emits light in a regular oblique direction. The car driver wears a pair of night glasses with the same polarization direction as the lampshade. In this way, the driver can only see the light emitted by their own car, and the vibration direction of the light emitted by the opposite car is exactly 90 degrees from the direction of the car; Angle, so that the light from the opposite headlight won't shake the driver's eyes anymore. Of course, realizing this idea still requires a long road. Firstly, the world must establish a unified standard to determine the polarization direction of lampshades and glasses; Secondly, polarized glasses will inevitably lose some light, which will affect the driver's field of view; Moreover, the power of car headlights is very high, and half of their energy is absorbed by polarizing lenses, which will definitely generate a large amount of heat. This is also a great test for the workmanship of car lampshades.