Hyper-radial or hyperradiant Fresnel lenses are Fresnel lenses used in

lighthouses A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mar ...

. They are larger than "first-order" lenses, having a focal length (radius) of 1330 mm (52.36 inches). The idea was mentioned by Thomas Stevenson in 1869 and first proposed by

John Richardson Wigham :''This article concerns the Irish-based inventor and lighthouse engineer, not his cousin the shipbuilder John Wigham Richardson''. John Richardson Wigham (15 January 1829 – 16 November 1906) was a prominent lighthouse engineer of the 19th ce ...

in 1872, and again proposed by Thomas Stevenson in 1885 (infringing Wigham's patent). The hyper-radial lens was made in 1885 by the F. Barbier Company in Paris as a test lens for the lighthouse illumination trials then going on at the South Foreland Lighthouse in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...

(UK). Chance Brothers Glass Company made their first hyper-radial lens in 1887 in the UK. These lenses were originally named biform, and later triform and quadriform lenses, by Wigham. Thomas Stevenson used the term hyperradiant lens, and later they were renamed the hyper-radial lens by James Kenward of the Chance Brothers Glass Company. The hyper-radial Fresnel lenses were the largest ever put into use and were installed in about two dozen major "landfall" beacons around the world. The recipients include Makapu'u Point lighthouse on

Oahu Oahu () ( Hawaiian: ''Oʻahu'' ()), also known as "The Gathering Place", is the third-largest of the Hawaiian Islands. It is home to roughly one million people—over two-thirds of the population of the U.S. state of Hawaii. The island of O ...

Island in

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

, Cabo de São Vicente in

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of th ...

, Manora Point in

Karachi Karachi (; ur, ; ; ) is the most populous city in Pakistan and 12th most populous city in the world, with a population of over 20 million. It is situated at the southern tip of the country along the Arabian Sea coast. It is the former c ...

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...

, the

Bishop Rock The Bishop Rock ( kw, Men Epskop) is a skerry off the British coast in the northern Atlantic Ocean known for its lighthouse. It is in the westernmost part of the Isles of Scilly, an archipelago off the southwestern tip of the Cornish penins ...

off the coast of

Cornwall Cornwall (; kw, Kernow ) is a Historic counties of England, historic county and Ceremonial counties of England, ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people ...

(in the UK), Cabo de Santa Marta in

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, and Cape Race,

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

. By the 1920s, high-intensity lamp technology had rendered lenses of this size obsolete.

Lighthouses

Hyperradiant optics were installed in thirty-one lighthouses around the world. A large proportion were destined for lights around Great Britain and Ireland, with another four used at sites around Sri Lanka. Despite the improvements in lighting technology, a number are still in use today. Others are in museums, either on display or in storage. The remainder have been broken up or lost.

References

External links

{{Commons category, Hyperradiant fresnel lenses, Hyperradiant Fresnel lenses
Wikimap showing lighthouse locations

Lenses History of physics Lighthouse fixtures