![](\"http:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2016\/11\/optical_stabilising_reference_cavity\/16545135-1-eng-GB\/Optical_stabilising_reference_cavity_small.jpg\")
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\nWhat looks like an abstract sculpture is actually the laser equivalent of a tuning fork \u2013 to serve a new generation of space instruments.\n<\/p>\n
\n\u201cThis is an \u2018optical stabilising reference cavity\u2019, through which laser light is contained between a pair of super-polished mirrors kept a precise distance apart,\u201d explains ESA physicist Eamonn Murphy.\n<\/p>\n
\n\u201dThis laser light is then used to lock the frequency of the laser \u2013 and prevent it drifting \u2013 in a similar principle to a tuning fork, as applied to musical instruments.\u201d\n<\/p>\n
\nSuch lasers will serve at the heart of next-generation \u2018optical atomic clocks\u2019, improving on current microwave atomic clocks used for timing and navigation, as well as enabling ultrasensitive gravity detectors.\n<\/p>\n
\nThis 5 cm cube cavity was developed for ESA by the National Physical Laboratory, NPL<\/a>, which is the national measurement institute of the UK, specialised in extremely precise measuring techniques.\n<\/p>\n \nNPL used ultra-low expansion glass, resistant to changing size with temperature. A pathway was then drilled through the middle, with mirrors placed at either end.\n<\/p>\n \nThe working version of the cavity is enclosed in a vacuum chamber<\/a> to prevent any disturbance by air molecules, followed by a thermal shroud to maintain its temperature to within a tiny fraction of a degree. It can then be placed on an acoustic damping baseplate to further isolate it from any microvibrations.\n<\/p>\n \nThis effort began back in 2009 with three parallel projects within ESA\u2019s Basic Technology Research Programme<\/a>, working with the national measuring institutes France and Germany as well as the UK.\n<\/p>\n \nExpertise and elements from all the resulting designs will soon be incorporated into a new working prototype, supported through ESA\u2019s General Support Technology Programme<\/a>, which finalises hardware for space.\n<\/p>\n \n\u201cOur aim is to deliver a six order-of-magnitude improvement in laser linewidth from initial laser performance,\u201d adds Eamonn, \u201cto maintain a stable drift-free frequency, insensitive to even minute accelerations.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":" \nWhat looks like an abstract sculpture is actually the laser equivalent of a tuning fork – to serve a new generation of space instruments.\n<\/p>\n \n“This is an ‘optical stabilising reference cavity’, through which laser light is contained between a pair of super-polished mirrors kept a precise distance apart,” explains ESA physicist Eamonn Murphy.\n<\/p>\n \n”This laser light is then used to lock the frequency of the laser – and prevent it drifting – in a similar principle to a tuning fork, as applied to musical instruments.”\n<\/p>\n \nSuch lasers will serve at the heart of next-generation ‘optical atomic clocks’, improving on current microwave atomic clocks used for timing and navigation, as well as enabling ultrasensitive gravity detectors.\n<\/p>\n \nThis 5 cm cube cavity was developed for ESA by the National Physical Laboratory, NPL<\/a>, which is the national measurement institute of the UK, specialised in extremely precise measuring techniques.\n<\/p>\n \nNPL used ultra-low expansion glass, resistant to changing size with temperature. A pathway was then drilled through the middle, with mirrors placed at either end.\n<\/p>\n \nThe working version of the cavity is enclosed in a vacuum chamber<\/a> to prevent any disturbance by air molecules, followed by a thermal shroud to maintain its temperature to within a tiny fraction of a degree. It can then be placed on an acoustic damping baseplate to further isolate it from any microvibrations.\n<\/p>\n \nThis effort began back in 2009 with three parallel projects within ESA’s Basic Technology Research Programme<\/a>, working with the national measuring institutes France and Germany as well as the UK.\n<\/p>\n<\/p>\n