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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:37 am
Between the 11th and 13th century "reading stones" were invented. These were primitive plano-convex lenses initially made by cutting a glass sphere in half.
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:37 am
The medieval (11th or 12th century) rock cystal Visby lenses may or may not have been intended for use as burning glasses
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:37 am
Spectacles were invented as an improvement of the "reading stones" of the high medieval period in Northern Italy in the second half of the 13th century.
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:37 am
This was the start of the optical industry of grinding and polishing lenses for spectacles, first in Venice and Florence in the late 13th century, and later in the spectacle-making centres in both the Netherlands and Germany.
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:37 am
Spectacle makers created improved types of lenses for the correction of vision based more on empirical knowledge gained from observing the effects of the lenses (probably without the knowledge of the rudimentary optical theory of the day).
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:38 am
The practical development and experimentation with lenses led to the invention of the compound optical microscope around 1595, and the refracting telescope in 1608, both of which appeared in the spectacle-making centres in the Netherlands
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:38 am
With the invention of the telescope and microscope there was a great deal of experimentation with lens shapes in the 17th and early 18th centuries by those trying to correct chromatic errors seen in lenses.
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:38 am
Opticians tried to construct lenses of varying forms of curvature, wrongly assuming errors arose from defects in the spherical figure of their surfaces.
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:39 am
Optical theory on refraction and experimentation was showing no single-element lens could bring all colours to a focus.
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Aditya992000
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 10:39 am
This led to the invention of the compound achromatic lens by Chester Moore Hall in England in 1733, an invention also claimed by fellow Englishman John Dollond in a 1758 patent.
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meenu007
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

on Wed Jan 16, 2019 11:40 am
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What is Optical Lens ? - Page 3 Empty Re: What is Optical Lens ?

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