Fresnel lens

The simpler dioptric (purely refractive) form of the lens was first proposed by Georges-Louis Leclerc, Comte de Buffon[2], and independently reinvented by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses.

[3][4] The catadioptric (combining refraction and reflection) form of the lens, entirely invented by Fresnel, has outer prismatic elements that use total internal reflection as well as refraction to capture more oblique light from the light source and add it to the beam, making it visible at greater distances.

[5] The first person to focus a lighthouse beam using a lens was apparently the London glass-cutter Thomas Rogers, who proposed the idea to Trinity House in 1788.

[6][7] In 1748, Georges-Louis Leclerc, Comte de Buffon was the first to replace a convex lens with a series of concentric annular prisms, ground as steps in a single piece of glass,[2]to reduce weight and absorption.

In 1790[8] (although secondary sources give the date as 1773[9]: 609  or 1788[10]), the Marquis de Condorcet suggested that it would be easier to make the annular sections separately and assemble them on a frame; but even that was impractical at the time.

[15] However, on 21 June 1819—three months after winning the physics Grand Prix of the Academy of Sciences for his celebrated memoir on diffraction—Fresnel was "temporarily" seconded to the commission on the recommendation of François Arago (a member since 1813), to review possible improvements in lighthouse illumination.

[11][16] By the end of August 1819, unaware of the Buffon-Condorcet-Brewster proposal,[11][13] Fresnel made his first presentation to the commission,[17] recommending what he called lentilles à échelons ('lenses by steps') to replace the reflectors then in use, which reflected only about half of the incident light.

The prototype, finished in March 1820, had a square lens panel 55 cm on a side, containing 97 polygonal (not annular) prisms—and so impressed the Commission that Fresnel was asked for a full eight-panel version.

[27] This refracted the light to a sloping plane mirror, which then reflected it horizontally, 7 degrees ahead of the main beam, increasing the duration of the flash.

The official test, conducted on the unfinished Arc de Triomphe on 20 August 1822, was witnessed by the Commission—and by Louis XVIII and his entourage—from 32 kilometres (20 mi) away.

[30] The day before the test of the Cordouan lens in Paris, a committee of the Academy of Sciences reported on Fresnel's memoir and supplements on double refraction—which, although less well known to modern readers than his earlier work on diffraction, struck a more decisive blow for the wave theory of light.

[31] Between the test and the reassembly at Cordouan, Fresnel submitted his papers on photoelasticity (16 September 1822), elliptical and circular polarization and optical rotation (9 December), and partial reflection and total internal reflection (7 January 1823),[32] essentially completing his reconstruction of physical optics on the transverse wave hypothesis.

[33] In May 1824,[13] Fresnel was promoted to Secretary of the Commission des Phares, becoming the first member of that body to draw a salary,[34] albeit in the concurrent role of Engineer-in-Chief.

[35] Late that year, being increasingly ill, he curtailed his fundamental research and resigned his seasonal job as an examiner at the École Polytechnique, in order to save his remaining time and energy for his lighthouse work.

[11] Ideally the curved refracting surfaces would be segments of toroids about a common vertical axis, so that the dioptric panel would look like a cylindrical drum.

[46] The first fixed lens to be constructed with toroidal prisms was a first-order apparatus designed by the Scottish engineer Alan Stevenson under the guidance of Léonor Fresnel, and fabricated by Isaac Cookson & Co. using French glass; it entered service at the Isle of May, Scotland, on 22 September 1836.

The first fully catadioptric lens with purely revolving beams—also of first order—was installed at Saint-Clément-des-Baleines in 1854, and marked the completion of Augustin Fresnel's original Carte des Phares.

[48] Thomas Stevenson (younger brother of Alan) went a step beyond Fresnel with his "holophotal" lens, which focused the light radiated by the lamp in nearly all directions, forward or backward, into a single beam.

Light radiated into the forward hemisphere but missing the bull's-eye lens was deflected by the paraboloid into a parallel beam surrounding the bull's-eye lens, while light radiated into the backward hemisphere was reflected back through the lamp by the spherical reflector (as in Rogers' arrangement), to be collected by the forward components.

[50] James Timmins Chance modified Thomas Stevenson's all-glass holophotal design by arranging the double-reflecting prisms about a vertical axis.

Double-flashing lenses were installed at Tampico (Mexico) and Little Basses (Sri Lanka) in 1875, and a triple-flashing lens at Casquets Lighthouse (Channel Islands) in 1876.

The first hyper-radial lens was built for the Stevensons in 1885 by F. Barbier & Cie of France, and tested at South Foreland Lighthouse with various light sources.

But only about 30 hyper-radials went into service[55] before the development of more compact bright lamps rendered such large optics unnecessary (see Hyperradiant Fresnel lens).

Production of one-piece stepped dioptric lenses—roughly as envisaged by Buffon—became feasible in 1852, when John L. Gilliland of the Brooklyn Flint-Glass Company patented a method of making lenses from pressed and molded glass.

Many Fresnel instruments allow the lamp to be moved relative to the lens' focal point, to increase or decrease the size of the light beam.

Fresnel lenses are used in left-hand-drive European lorries entering the UK and Republic of Ireland (and vice versa, right-hand-drive Irish and British trucks entering mainland Europe) to overcome the blind spots caused by the driver operating the lorry while sitting on the wrong side of the cab relative to the side of the road the car is on.

The British rock artist Peter Gabriel made use of them in his early solo live performances to magnify the size of his head in contrast to the rest of his body, for dramatic and comic effect.

In the Terry Gilliam film Brazil, Fresnel lenses are used as magnifiers for small CRT monitors in the Ministry of Information.

[77] Newer devices, such as the Meta Quest Pro, have switched to a pancake lens design[78] due to its smaller form factor and less chromatic aberration than Fresnel lenses.

Many cameras are equipped with viewfinders which project the scene through a lens onto a ground glass screen for focusing and composition, including view, twin-lens reflex, and single-lens reflex cameras; often a Fresnel condenser lens is applied to the ground glass to increase the perceived brightness of the projected image and make the illumination more even from center to corner.