Night-vision glasses work by capturing tiny amounts of light, some of it from the infrared portion of the light spectrum, and amplifying it in order to create an image that is more easily observed. Some systems may also utilize thermal imaging technology, either alone or in concert with light amplification.Continue Reading
Night vision devices capture a minute quantities of visible light through a special component known as an image intensifier tube. This tube utilizes both a conventional lens and a photocathode to convert photons into electrons which are then amplified through the use of a microchannel plate. The amplified electrons that exit the image intensifier tube strike a plate that has been coated with phosphors in order to create a visual image. This image is then viewed through an ocular lens which provides additional magnification and focus.
Thermal imaging devices make use of a lens which collects light from within the infrared spectrum. Once this light has been focused, it is scanned by a phased array of infrared-detector elements. These elements are able to create a detailed pattern based called a thermogram which is then translated into electrical signals. A signal processing unit is then used to create an observable image that is based on the information contained within the thermogram.Learn more about Glasses & Contacts
According to manufacturers such as Trayner, pinhole glasses can permanently improve eyesight and relieve eyestrain, fatigues and headaches. However, the College of Optometrists warns that such claims are unsubstantiated and are best viewed with caution.Full Answer >
Bifocal glasses work by correcting both near- and far-sightedness in an eye using two different sections of the lens, each having its own point of focus. For most bifocals, the nearsightedness is corrected in the top portion of the lens, while the farsightedness is corrected in a smaller portion of the lens toward the bottom, where one generally looks while reading. A double segment bifocal lens has a near or reading portion on the top and bottom of the lens.Full Answer >
Bifocal contact lenses work similarly to bifocal eyeglasses, providing two different prescriptions in a single lens for close and distant vision clarity. Some bifocal contacts split the lens into two zones, while others have near and far prescriptions arranged in rings and rely on the brain to process visual focus.Full Answer >
To fixed scratched glasses, clean them with water and dish soap, and remove a scratched lens coating with sunscreen. For deeper scratches, buff out the scratches with a paste of baking soda and water or a nonabrasive toothpaste. Use a four-way nail buffer to remove scratches on a frame.Full Answer >