Photomultiplier tube

Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a>, <a href="/facts/Visible_light/jeofpMn4">visible</a>, and <a href="/facts/Near-infrared/44XdJNcc">near-infrared</a> ranges of the <a href="/facts/Electromagnetic_spectrum/24LARvFY">electromagnetic spectrum</a>. They are members of the class of <a href="/facts/Vacuum_tube/VHd1BNLq">vacuum tubes</a>, more specifically vacuum <a href="/facts/Phototube/JUfNjJ1j">phototubes</a>. These detectors multiply the current produced by incident light by as much as 100 million times or 108 (i.e., 160 <a href="/facts/Decibel/0LyxAPXh">dB</a>), in multiple <a href="/facts/Dynode/0YFFKB86">dynode</a> stages, enabling (for example) individual <a href="/facts/Photons/mFNhAEzA">photons</a> to be detected when the incident <a href="/facts/Flux/Aw3P5Bvb">flux</a> of light is low.

The combination of high <a href="/facts/Gain_(electronics)/CWbehg27">gain</a>, low <a href="/facts/Noise_(electronics)/Izbv38Rr">noise</a>, high frequency response or, equivalently, ultra-fast response, and large area of collection has maintained photomultipliers an essential place in <a href="/facts/Spectroscopy/mj71FuNK">low light level spectroscopy</a>, <a href="/facts/Confocal_microscopy/Gh7pY9Cl">confocal microscopy</a>, <a href="/facts/Raman_spectroscopy/XY063k29">Raman spectroscopy</a>, <a href="/facts/Fluorescence_spectroscopy/mBcweHKk">fluorescence spectroscopy</a>, <a href="/facts/Nuclear_physics/fzQbt1aF">nuclear</a> and <a href="/facts/Particle_physics/YgIuyj2t">particle physics</a>, <a href="/facts/Astronomy/0ArJVM1p">astronomy</a>, medical <a href="/facts/Diagnostics/VcsPwshd">diagnostics</a> including <a href="/facts/Blood_tests/zevsf3rC">blood tests</a>, <a href="/facts/Medical_imaging/pL6JyJEp">medical imaging</a>, motion picture film scanning (<a href="/facts/Telecine/TfB3cWqL">telecine</a>), <a href="/facts/Barrage_jamming/sb0N37C9">radar jamming</a>, and high-end image scanners known as <a href="/facts/Drum_scanner/7DEJFTwx">drum scanners</a>. Elements of photomultiplier technology, when integrated differently, are the basis of <a href="/facts/Night_vision_device/jJ58YGa0">night vision devices</a>. Research that analyzes <a href="/facts/Light_scattering/nMou7lEH">light scattering</a>, such as the study of <a href="/facts/Polymers/eF32E50K">polymers</a> in solution, often uses a laser and a PMT to collect the scattered light data.
<a href="/facts/Semiconductor_device/6W3ryr50">Semiconductor devices</a>, particularly <a href="/facts/Silicon_photomultiplier/fg5Mx48B">silicon photomultipliers</a> and <a href="/facts/Avalanche_photodiode/x2eUFfgF">avalanche photodiodes</a>, are alternatives to classical photomultipliers; however, photomultipliers are uniquely well-suited for applications requiring low-noise, high-sensitivity detection of light that is imperfectly <a href="/facts/Collimated_light/lhd2hhPt">collimated</a>.

Photomultiplier tube open-in-new

Photomultiplier tube