Editing Infrared homing (section)

===Early research===
[[File:Vampir night scope.jpg|thumb|right|The ''Vampir'' nightscope used a photomultiplier as the sighting system and provided illumination with an IR lamp mounted above the scope.]]

The ability of certain substances to give off [[electron]]s when struck by infrared light had been discovered by the famous [[Indian people|Indian]] polymath [[Jagadish Chandra Bose]] in 1901, who saw the effect in [[galena]], known today as lead sulfide, PbS. There was little application at the time, and he allowed his 1904 patent to lapse.<ref>{{cite journal |first=V |last= Mukherj |title= Some Historical Aspects of Jagadls Chandra Bose's Microwave Research During 1895—1900 |journal=Indian Journal of History of Science Calcutta |date=February 1979 |pages=87–104}}</ref> In 1917, [[Theodore Case]], as part of his work on what became the [[Movietone sound system]], discovered that a mix of thallium and sulfur was much more sensitive, but was highly unstable electrically and proved to be of little use as a practical detector.{{sfn|Rogalski|2000|p=3}} Nevertheless, it was used for some time by the [[US Navy]] as a secure communications system.<ref>{{cite book |last=Fielding |first= Raymond |date=1967 |title= A Technological History of Motion Pictures and Television: An Anthology from the Pages of "The Journal of the Society of Motion Pictures and Television" |publisher=University of California Press |page=179}}</ref>

In 1930 the introduction of the Ag–O–Cs ([[silver]]–[[oxygen]]–[[cesium]]) [[photomultiplier]] provided the first practical solution to the detection of IR, combining it with a layer of galena as the [[photocathode]]. Amplifying the signal emitted by the galena, the photomultiplier produced a useful output that could be used for detection of hot objects at long ranges.{{sfn|Rogalski|2000|p=3}} This sparked developments in a number of nations, notably the UK and Germany where it was seen as a potential solution to the problem of detecting [[night bomber]]s.

In the UK, research was plodding, with even the main research team at [[Cavendish Labs]] expressing their desire to work on other projects, especially after it became clear that [[radar]] was going to be a better solution. Nevertheless, [[Frederick Lindemann]], [[Winston Churchill]]'s favorite on the [[Tizard Committee]], remained committed to IR and became increasingly obstructionist to the work of the Committee who were otherwise pressing for radar development. Eventually they dissolved the Committee and reformed, leaving Lindemann off the roster,{{sfn|Hastings|1999|p=129}} and filling his position with well known radio expert [[Edward Victor Appleton]].<ref>{{cite book |url=https://books.google.com/books?id=TAppUf7bRLgC&pg=PA577 |title=A Scientist's War: The War Diary of Sir Clifford Paterson, 1939-45 |first1=Clifford |last1=Paterson |first2=Robert |last2=Clayton |first3=Joan |last3=Algar |page=577 |publisher= IET |date=1991|isbn=9780863412189 }}</ref>

In Germany, radar research was not given nearly the same level of support as in the UK, and competed with IR development throughout the 1930s. IR research was led primarily by [[Edgar Kutzscher]] at the [[University of Berlin]]<ref>{{cite book |first=Sean |last=Johnston |title=A History of Light and Colour Measurement: Science in the Shadows |publisher=CRC Press |date=2001 |pages=224–225 |isbn=9781420034776 |url=https://books.google.com/books?id=2wNVPfNkLpEC&pg=PA224}}</ref> working in concert with [[AEG (German company)|AEG]].{{sfn|Rogalski|2000|p=3}} By 1940 they had successfully developed one solution; the ''Spanner Anlage'' (roughly "Peeping Tom system") consisting of a detector photomultiplier placed in front of the pilot, and a large searchlight fitted with a filter to limit the output to the IR range. This provided enough light to see the target at short range, and ''Spanner Anlage'' was fitted to a small number of [[Messerschmitt Bf 110]] and [[Dornier Do 17]] [[night fighters]]. These proved largely useless in practice and the pilots complained that the target often only became visible at {{convert|200|m|feet}}, at which point they would have seen it anyway.<ref>{{cite book |first= Robert |last=Forczyk |title= Bf 110 vs Lancaster: 1942-45 |publisher= Osprey Publishing |date=2013 |page=22}}</ref> Only 15 were built and were removed as German airborne radar systems improved though 1942.<ref>{{cite book |first= Alastair |last=Goodrum |title= No Place for Chivalry |date=2005 |publisher=Grub Street |page=109}}</ref>

AEG had been working with the same systems for use on [[tank]]s, and deployed a number of models through the war, with limited production of the [[FG 1250]] beginning in 1943.{{sfn|Rogalski|2000|p=3}} This work culminated in the [[Zielgerät 1229]] ''Vampir'' riflescope which was used with the [[StG 44]] [[assault rifle]] for night use.<ref>{{cite book |first=Chris |last=McNab |title=German Automatic Rifles 1941-45 |publisher=Osprey |date=2013 |pages=63–64 |isbn=9781780963853 |url=https://books.google.com/books?id=qU2kAwAAQBAJ&pg=PA63 }}{{Dead link|date=September 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>