Section of 36 inch high fixed-lens (fourth order) lighthouse optic, 1890-1900.

Section of 36 inch high fixed-lens (fourth order) lighthouse optic, 1890-1900.
2 5 c m
40cm
actual image size: 32cm x 17cm

Description

Large lenses, like those used in lighthouses, can be very heavy and distort at the edges. In 1748 Georges de Buffon thought of a way to lighten them and reduce energy los. He realised that only the surface of a lens is needed to bend light, because once the light is inside the lens it travels in straight lines. The insides of the lens could be cut away, leaving rings with angled edges. Buffon's idea was modified by Augustin Fresnel (1788-1827), who fitted lenses in lighthouses.

© Science Museum / Science & Society Picture Library

buy a print

Select size
 
Select finish
 
How many prints?
 
£20.00
 

buy a framed print

buy a canvas

buy a framed canvas

image details