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History of eyeglasses essay
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A lens is an optical device that transmits or refracts light. Eyeglass lenses are glass or plastic items that are placed inside eyewear frames in order to correct the wearer’s 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 concave lenses are known as spherical lenses. Convex lenses were the first lenses used to correct vision problems. They are used to correct hyperopia (farsighted vision). These lenses are thicker 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 but struggle to see things far away. Concave lenses are curved inward 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. Years ago opticians relied on separate optical laboratories to produce eyeglass lenses. However 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. Eyeglass lenses are designed in many shapes in order to match the eyeglass frame.
Assuming that plastic lenses are being made at an optical laboratory technician’s input optical prescription for a pair of lenses i...
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... may also verify optics and optical prescription in the lensometer.
The manufacturing of lens has progressed over the years. The labor-intensive nature of making glasses has made it hard 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 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 assisted 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 important to know that the manufacturing of lenses requires strict adherence to guidelines and quality control.
Lens Crafters is an international eye care, eyewear, and sunglass organization. Their mission statement sums it up “We love your eye.” The overall goal is to provide better sight & eye care for everyone. The company started in 1983. It currently has stores domestically and internationally. The company has 90 stores and was founded by E. Dean Butler. LensCrafter has independent Optometrist in their store; the operation strategy that will stabilize and overall support their vision that will lead to increase profits within their business.
1.4 – State why and when health and safety control equipment, identified by the principles of protection, should be used relating to types, purpose and limitations of each type, the work situation, occupational use and the general work environment, in relation to: • Collective protective measures • Personal protective equipment (PPE) • Respiratory protective equipment (RPE) • Local exhaust ventilation (LEV) PPE Whilst working on site we wear PPE to eliminate the chances of injury. We wear protective eye glasses as we are using tiles, when cutting and nipping them sharp bits of tile can come off and there’s a chance it could damage your eyes, in this case the glasses will prevent this happening.
The fictional novel Lord of the Flies by William Golding is one of the first popular endurance novels of it’s time. The Lord of the Flies takes place during World War 2 and during this time, children were being brought out of war zones via plane. A group of boys were being evacuated from their homes to escape the war, when their plane crashed on a remote island, the only survivors a group of young boys. The island that they landed on would become the center for their savageous “game”, until they get rescued at the end of the novel. Once arriving on the island, Ralph, the book’s hero, is voted leader by the boys and he sets out to create a functioning and reasonable civilization amongst the boys. Conflict is present right away when Jack, the
example the effect the war had on Carlo is evident on page 40 when he
Warby parker design, manufacture glasses themselves and provide trendy, higher quality prescription eyewear directly to customers at a much lower price. They believe that customers should be feeling happy with their good-looking and pay less. Warby Parker goal is:
In addition, astigmatism requires a person to wear prescription eyeglasses and/or contact lenses. Astigmatism arises when the curvature of the eye is irregular. The eye is normally shaped like a soccer ball or basketball. With astigmatism, it takes on a more oval shape and resembles a football. Due to the irregular curvature, the eye processes light differently and leads to blurred vision.
(Beam "What Are Bifocals?"). With these two-line bifocals one can look through the upper half to see far away and the lower half to see closer things. Many historians question who invented the bifocals although, due to letters written by Benjamin Franklin to his friend George Whatley, it is a known fact that Franklin was indeed the true inventor of the bifocals (The Electric Franklin "Benjamin Franklin's Inventions"). They are generally used by people over forty years old (Heating "Bifocals and Trifocals for Vision Over 40"). Single vision glasses and bifocals are very different types of glasses because they only help people with nearsightedness.
The crystalline lens is a fibrous, jelly-like material that serves to fine tune the vision process by adjusting its shape and therefore the focal length of the system.
The principle behind the refractive telescopes is the use of two glass lenses (objective lens and eyepiece lens) to gather and bend parallel light rays in a certain way so that the image fits the size of the eye's pupil. Light rays is gather through the opening of the telescope called the aperture and passes through the objective lens and refracts onto a single point called the focal point. From there the light rays continue the same direction until it hits the eyepiece lens which also refract the light back into parallel rays. During the process, the image that enters our eyes is actually reverse of the original image and magnified because the size in which we preceive the image.
There is evidence of glass making from as early as 4000 BC. Back then it was mostly used for the coating of stone beads. It was 1500 BC when the first hollow glass container was made. It was made by covering a sand core with a layer of molten glass. It was during the First Century BC that glass blowing became more common. At this time glass was high coloured due to the impurities of the raw materials that were used to make it. The first recorded colourless glass was made in First Century AD. The Romans were one of the most skilled in glass making and held most of the secrets. It wasn’t until the Roman Empire began to fall that the secrets began to leak out into Europe and the Middle East. At this time the greatest reputation for technical skill and artistic ability was held by the Venetians. A far amount of Venetian craftsmen left Italy to set up their own glassworks.
“A dispensing optician’s role entails, advising on, fits, supplying, and recommending the most appropriate spectacles after taking into account a patient’s visual, lifestyle and vocational needs”. (https://www.optical.org/en/Education/Careers/Pre-registration_home.cfm)
Observation – Magnifying glasses are normally made of convex lenses. A convex lens is thin on the outer edges and are thicker in the center. They bend light inwards towards a focal point. They can be used to make objects appear larger than they actually are. This is accomplished by placing the lens close to the object or item. In this way, the light rays are bent towards the center of the lens creating a focal point. When the bent rays hit the retina, it will make the object appear larger than it actually is. The distance the lens are from the surface of the item or object affects the size of the focal point. The focal point of the lens are also determined by the curvature of the lens too. Many people have used a magnifying glass and sunlight
The refracting telescope is one of many different types of telescope. Refracting telescopes work by refracting the light through an initial convex lens, (known as the objective lens), then through another convex lens (known as the eyepiece lens). These two lenses focus the light into the eyepiece so we can see the image clearly.
The achromatic lens that first appeared in a 1733 telescope made by Chester Moore Hall, John Hadley's production of larger paraboloidal mirrors in 1721, the process of silvering glass mirrors introduced by Léon Foucault in 1857, and the adoption of long lasting aluminized coatings on reflector mirrors in 1932 evolved the telescopes to higher levels of performance and accuracy.
...he cornea is deformed so that its surface is oval instead of spherical. Light rays are distorted at the entrance of the eye. This produces a blurred image and is known as astigmatism. To correct it, glasses are given a nonspherical or cylindrical curvature. Cross-eyes and walleyes are produced when both eyes do not work together because of weakness of the eye muscles.