Wave optics Fresnel lens The principles Commentary

Augustin-Jean Fresnel, François Arago optics

Wave optics

• Sound waves vibrate longitudinally,
• that is, along the direction they travel.
• Thomas Young proposed
• that light waves were mainly longitudinal.
• But Augustin-Jean Fresnel
• worked with François Arago
• to establish the laws of interference
• between rays of polarized light,
• and realized, in order to explain polarization,
• that light waves were entirely transverse.

Fresnel lens

• Fresnel took the idea of making a lighter lens
• with sections separated by stepwise discontinuities
• from Georges-Louis Leclerc, Comte de Buffon,
• or Nicolas de Caritat, marquis de Condorcet.
• As commissioner of lighthouses in France
• he designed a series of different-size lenses
• and was the first to build these large-aperture
• and short-focal-length lenses for lighthouses.

The principles

• The basic principles survive
• and are reapplied
• in unanticipated
• contexts.
• Augustin-Jean Fresnel created
• an object of beauty
• for which each lens facet,
• each mount, each screw
• was made by hand to amaze
• for hundreds of years.