bifocal lens

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Nero (Nero Claudius Caesar Augustus Germanicus) (ad 50-54) the fifth Roman emperor (ad 54-68), stepson and heir of the emperor Claudius.

Did Nero Really Fiddle as Rome Burned?

Scolex (head) of the tapeworm Taenia solium. The hooks of the scolex enable the tapeworm to attach to the intestinal wall.

Uninvited Guests: The 7 Worst Parasitic Worms

Small, white rat (genus Rattus) on a glass table. (rodent, laboratory, experiment)

Cruel and Unusual Punishments: 15 Types of Torture

Bristlecone pine (Pinus Longaeva) on the slope of Mount Washington in Great Basin National Park in the Nevada desert.

How Can Some Trees Survive for Thousands of Years?

Leonardo da Vinci (1452-1519), Italian Renaissance painter from Florence. Engraving by Cosomo Colombini (d. 1812) after a Leonardo self portrait. Ca. 1500.

10 Famous Artworks by Leonardo da Vinci

King Cobra snake in Malaysia. (reptile)

9 of the World’s Deadliest Snakes

Dr. Martin Luther King Jr. addresses marchers during his "I Have a Dream" speech at the Lincoln Memorial in Washington. August 28th 1963

Was Martin Luther King, Jr., a Republican or a Democrat?

bifocal lens

optics

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use in optical systems

In optics: Nonclassical imaging systems
…nonclassical optical system is the bifocal or trifocal spectacle lens. They are made either by forming two or three separate surfaces on a single piece of glass or obtaining additional power by fusing a piece of high-index glass on to the front of the main lens and then polishing a…
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