Essay example --

A lens is an optical device that transmits or refracts light. eye nut case lenses be glass or plastic items that argon placed inner(a) eyewear frames in order to gear up the we arrs vision. More than 80 percent of all eyeglasses worn today are plastic lenses. The glass lenses were popular in the 1945 until the plastic lens was introduced in 1952. Convex and acetabular lenses are known as spherical lenses. Convex lenses were the first lenses utilize to correct vision problems. They are used to correct hyperopia (farsighted vision). These lenses are inscrut adequate to(p)er in the middle than at the edges. Concave lenses are used to correct nearsightedness. This is a condition that makes people see things that are close to them only when struggle to see things far away. Concave lenses are curved in like the inside of a spoon. Whether you have plastic or glass, concave lenses or convex lenses they are produced in much of the same way. days ago opticians relied o n separate optical jabatories to produce eyeglass lenses. thus far today optical outlets receive lens blanks (blanks received from optical laboratories) which are plastic pieces already formed to fit exactly into the front of the lens. The stages are grinding, polishing, and shaping. Materials used are plastic or glass blanks, which are thick in size to eyeglass frames, though slightly larger. Thickness may vary depending upon the prescription. Other raw materials used to make eyeglass lenses are adhesive tape, a liquid with a lead alloy base, metal, and dyes and tints. monocle lenses are designed in many shapes in order to hit the eyeglass frame. Assuming that plastic lenses are being make at an optical laboratory technicians input optical prescription for a pair of lenses i... ... may also verify optics and optical prescription in the lensometer. The manufacturing of lens has progressed over the years. The labour-intensive nature of making glasses has made it har d for U.S. companies to make high-precision lenses to compete with forms located in countries with low labor costs. However the manufacturing process has become more than automated which makes the process more capital intensive rather than labor intensive. American companies are able to compete on even ground. Now there is computer back up grinding process using the Opticam. This machine is capable of surfacing, edging, and centering in one setup, which save so much time. Whether you use the old-fashioned labor-intensive approach or use newly developed technology it is alpha to know that the manufacturing of lenses requires strict adherence to guidelines and quality control.