Optical lenses have been in use since many decades. These lenses were first discovered and used by the ancient Egyptians, if sources are to be believed. Various types of glasses were used as lenses for better vision. The first corrective eye lens was discovered by the Italians in the 13th century. Later on designer tinted eye glasses came into prominence. Even today various types of lenses are used as eye glasses.
It was Ben Franklin who invented the bifocal lenses by grinding together two pairs of optical lenses. These lenses are quite expensive as it has to be cut, molded, polished and tested before it is used in eye-glasses. The green lens is another latest invention of organic lenses invented by the scientists.
Types of Lenses:
Single Vision: These types of glasses are required by people with eye problems such as nearsightedness and farsightedness. These eye conditions typically develop due to various problems with the eyeball. Single vision glasses are often worn by people with simple eye problems.
Reading Glasses: Some people have difficulties in reading and close vision. These glasses are often prescribed by optometrist to such patients.
Multifocal: Some people experience both long sightedness and short sightedness. Multifocal glasses are prescribed for such people as it provides better sight and ability to read.
Light Protection: There are special light protection glasses that offer protection from UV rays. The polarized sun glasses help to block the UV rays and reduce the glare of the sun. Transition lenses are another variety of glasses that darken when exposed to UV rays and remain clear when indoors.
The operation of a binocular begins with the human eye. Binoculars function in a unique way as human eyes itself have binocular effects which functions by combining the images produced by the binoculars to form an in-depth perception.
There are various types of binoculars available in many of the online stores at various price rates. Some of these binoculars differ in functions, features and use. The Galilean binoculars are basically telescopes which are mounted side by side. It is usually found in opera glasses. These devices can seldom achieve high magnification as it is quite simple in design and structure.
Some of the binoculars include various functional options. Independent focus is one of the additional features included in these binoculars which have controls that can be used to adjust the focus of the eyepieces independently. It is mainly found in military binoculars as it also includes anti-reflective coating.
The prism binocular is another variety of binocular which uses optical lenses. It includes greater magnification than the Galilean models of binoculars. With the use of prisms, these devices correct the vision of the image.