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Posted by on Jun 26, 2016 in Tell Me Why |

How Old Is the Lens and What Is the Practical Use of It?

How Old Is the Lens and What Is the Practical Use of It?

The oldest known lens was found in the ruins of ancient Nineveh, and was made of polished rock crystal, 4 centimeters in diameter. Around the year 1752, eye glass designer James Ayscough introduced his spectacles with double-hinged side pieces. The lenses were made of tinted glass as well as clear.

Ayscough felt that white glass created an offensive glaring light that was bad to the eyes. He advised the use of green and blue glasses. Ayscough glasses were the first sunglass like eyeglasses, but they were not made to shield the eyes from the sun, they corrected for vision related problems.

Edwin H. Land invented a cellophane-like polarizing filter (patented in 1929), the first modern filters to polarize light. Polarizing celluloid became the critical element in polarizing sunglass lenses: it is a process that reduces light. The first practical use of glass lens was not in a microscope or a telescope, but in eye glasses!

Although Grosseteste and Bacon began the basic research on eye glasses, no one knows the name of the man who made the first working pair of spectacles. Lenses came into widespread use in Europe with the invention of spectacles, probably in Italy in the 1280s. This was the start of the optical industry of grinding and polishing lenses for spectacles, first in Venice and Florence in the thirteenth century, and later in the spectacle-making centres in both the Netherlands and Germany.

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). 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.

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 trying to correct chromatic errors seen in lenses. Opticians tried to construct lenses of varying forms of curvature, wrongly assuming errors arose from defects in the spherical figure of their surfaces.

Optical theory on refraction and experimentation was showing no single-element lens could bring all colors to a focus. 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.

Content for this question contributed by Jason Brown, resident of Los Gatos, Santa Clara County, California, USA