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| Linear Polarizing ₯@Circular Polarizing ₯@Applications₯@Polarized 3D ₯ |
| Polarized light is light (electromagnetic waves) that vibrate only in a specific direction. Polarizing films' principal purpose is to change ordinary light, which vibrates at 360 degrees in all directions, into light that vibrates only in a particular direction. When a 1/4Ι retardation film is installed 45 degrees in the direction of the light vibrating in a specific order, the light will rotate and become circularly polarized. |
| @Linear Polarizer (Principle and Illustration) |
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| When normal light, which vibrates randomly at 360 degrees, passes through
the polarizer, the fine slit structure of the polarizer allows vertical waves to pass through and horizontal waves to be absorbed and not transmitted. Also, the vertical component of the diagonally vibrating wave is transmitted, and the horizontal part is absorbed. Therefore, the theoretical limit of the transmittance of a polarizer is less than 50%. (* Products with high transmittances, such as polarizing films for educational purposes and polarizing sunglasses for sports, also transmit some ordinary light.) |
| @Circular Polarizer (Principle and Illustration) |
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| A circular polarizing film consists of a linear polarizing film and a 1/4
(retarder) plate. When the 1/4 wave plate's slow axis is aligned at 45 to the linear polarizer's absorption axis, the result is a circular polarizer with right-hand rotation. Similarly, when the slow axis of the 1/4 wave plate is aligned at 135 (-45), it becomes a left-rotating circular polarizer. Light is blocked when the right/left circular polarizer is layered with the 1/4 wave plate side inside |
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| Unlike linear polarizing film, the circular polarizing film does not lose
its light-shielding capability even when the intersection angles of their absorption axes change. (However, it is darkest when the absorption axis of the linear polarizer is orthogonal) |
| @Applications of Polarizers (Polarizing Film) |
| PL Filter ₯@Sunglasses ₯@Light intensity adjustment ₯@LCD ₯ |
| Optical communication ₯@Polariscope (strain inspection) ₯@3D glasses ₯ |
| @✓ PL (polarizing) Filters for Cameras |
| When a polarizing filter is attached, the amount of reflected light can
be controlled according to its direction and this makes it possible to suppress reflected light when shooting near water or suppress reflections from window glass. It is also used as a color contrast filter for digital cameras, as it suppresses diffuse reflections from the air and increases the color contrast of the sky or wet leaves compared to the naked eye. (Polarizing filters for cameras use a circular polarizer to prevent interference with internal prisms) |
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| No FIlter | Polarizing filter used |
| The polarizing filter reduces the diffuse reflection of dust and water vapor in the air and can enhance color contrast, such as deepening the colors of blue sky, green, and water. |
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| Reference URL : https://hoyafilter.com/support/how_filters_work/pl/ | |
| @✓ Polarized Sport Sunglasses |
| The absorption axis of polarized sports sunglasses (for driving, fishing, skiing) is horizontal. They can be used to suppress reflection on the water's surface and enable observation of fish under the water. They can also be used to reduce reflections from puddles of water on the road after rain, or sunlight from oncoming cars, and reflections from the snow. |
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| Light reflected diagonally on the water surface becomes polarized in a
vertical oscillation. Polarized sports sunglasses, which have the absorption axis horizontal on both the left and right sides, absorb reflected light and allowing you to see underwater (natural light) without being disturbed by reflected light from the sky. |
| @✓ Light intensity adjustment |
| Two polarizers are often installed in the window of a commercial aircraft,
and the amount of incoming light can be adjusted by rotating the inner polarizing plate. |
| Reference URL : https://www.youtube.com/watch?v=2hRibmDwe1A |
| @✓ LCD |
| Polarizing filters, which allow only certain types of linearly polarized light to pass through, are attached to LCD monitors' front and back surfaces. The liquid crystal controls the optical rotation and birefringence of each pixel to display the image. |
| @✓ Enhancement of optical communications |
| Adding polarization to the light in fiber-optic communications is used
to increase the number of channels and improve reliability by removing noise. |
| @✓ Polariscope (strain inspection) |
| Polariscope is a device for visualizing the amount of internal strain in
resins and glasses. By placing a transparent object between two linear or circular polarizer and illuminating it with light from below, it is possible to see the strain as a specific color according to its intensity. There are three methods: Parallel Nichol method, in which polarizers are placed parallel to each other Cross Nichol method, in which polarizers are placed orthogonal to each other Sensitive color method, in which objects with little distortion such as glass can be observed |
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| Cross Nicols | Senstive Color |
| Reference URL : https://www.mecanusa.com/visualization/mrv330.htm |
| @✓ Polarized 3D glasses |
| The stereoscopic sensation is constructed in the brain by the parallax (misalignment) between the right eye and the left eye. Images taken by 2 cameras separated by a distance on the left/right are projected by two projectors with polarizing filters. When the images are viewed through special 3D glasses with polarizing filters, the left and right images can be perceived separately and can be viewed as 3D images. |
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| Reference URL : mecanusa.com/Polarizer-Polarizing-Film/Polarized-3D-System-Instruction.htm |
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