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Optical Products > International Polarizer > Vedere Tech
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Polarized Lens Market Increasing!
International Polarizer, Inc. of Marlborough (MA, USA) manufacturers polarizers for scientific, electronic and eyewear markets. The firm, founded in 1985 by leading physicists and Dr. Richard A. Phillips, who is also chairman, applies its expertise, developed in manufacturing films for scientific applications, to the manufacture of films for the eyewear market. It is the world’s largest producer of polarized plastic sheet for the eyewear OEM market. Its staff of renowned scientists continually works to develop improved processes and new uses for polarizers.
Light and Polarization
Light interacts with the eye, solid surfaces and fluids by its wave nature. The three wave properties of light are interference, diffraction and polarization. In the discovery and understanding each of these fundamental properties of nature, Europeans played the historical key role.
Robert Hooke of the Royal Society in London discovered interference. He correctly explained colored interference patterns in thin films by interference between the light reflected from the front and rear surfaces of the film.
Professor Francesco Maria Grimaldi at Jesuit College in Bologna discovered diffraction. He observed bands of light in the shadow of objects illuminated by a point source. The effect is explained by bending of light as it passes close to an obstacle, such as pinhole or knife edge.
Etienne Louis Malus, a French army engineer, discovered polarization. He was intrigued by the crystal calcite. When an object is viewed through a crystal of calcite two images are produced (double refraction). One afternoon Malus examined reflections from the windows of the Palace of Versailles through crystal of calcite. He discovered that at certain angles the crystal produced only one image, not two images.
He correctly explained this by assuming that light can have two sides (polarization) and at certain angles only light of one side is reflected (i.e. It is completely polarized). For solid materials, such as sand or glass, light reflected at an angle of 56 degrees is completely polarized. For water, light reflected at 53 degrees is completely polarized.
Light that is reflected from a horizontal surface such as water, beach, road or snow is called glare and is undesirable. The figure below illustrates how polarizes function to eliminate glare. At the polarizing angle (53 to 56 degree) glare is 100% polarized. A polarizer with its absorption axis oriented in the horizontal plane, completely absorbs the glare.
Advantages for eyewear
Only polarized lenses have the ability to selectively eliminate the undesirable glare. Other sunlenses make viewing comfortable by absorbing part of all types of incoming light. However, they reduce glare by the same amount that they reduce other incoming light. By adding dyes or absorbers to polarized lenses additional functions are produced. Adding UV absorbing dyes can eliminate 99% of the UV-A and UV-B.
Selection of colors
Standard tints are the grey or brown family with transmittance typically between 18% and 24%. Medium grey is a neutral color, which can nicely combine with any color of frame. Dark grey provides greater protection. Brown harmonized with skin tones. Enhanced performance tints can be darker, such as the Retina-Guard, a greenish grey with transmittance of 15% (G15). The Blue Glare-Guard, which is in the orange family, or Sportsman’s Yellow attenuate the blue light; this improves contrast. Special purpose polarizers absorbs only a portion of the visible light. These provide higher transmittance while selectively absorbing glare of certain wave-lengths. Two of these are the Haze Fighter and Vermilion. Both are used in sports applications. Polarizing films are available in thickness of 0.74 mm and 1.1 mm and in the form of panels and reels.
Better to make the consumer aware of the advantages of polarization, International Polarizer devised Polarscenes, salespoint-displays showing the pluspoints and practical effects of a polarising lens. These displays present situations where polarising lenses offer the greatest advantages, such as fishing, skiing, motoring, hunting, and water sports.
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