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LIGOLASER INTERFEROMETER GRAVITATIONAL-WAVE OBSERVATORY
Physics 43, SRJC
What is LIGO?
The laser interferometers at LIGO use the fringe pattern of a divided laser beam to measure any lengthening or shortening of space due to gravitational waves. The divided laser beam will travel through two steel vacuum tubes oriented at a right angle. When a gravitational wave distortion causes one beam to lengthen and the other to shrink, the interference pattern of the two beams will. LIGO was first designed to have an effective range of ~70 million light years.
Facts of LIGO
LIGO's interferometers are the world's largest precision optical instruments. They are housed in one of the world's largest vacuum systems (volume of nearly 300,000 cubic feet). The beam tubes and associated chambers must be evacuated to a pressure of only one-trillionth of an atmosphere, so that the laser beams can travel in a clear path with a minimum of scattering due to stray gases. To do this they use a steel with a very low dissolved hydrogen content.
The LIGO laser light comes from high-power, solid-state lasers that must be so well regulated that, over one hundredth of a second, the frequency will vary by less than a few millionths of a cycle.
The suspended mirrors must be so well shielded from vibration that the random motion of the atoms within the mirrors and suspension fibers can be detected.
More than 30 different control systems are required to hold all the lasers and mirrors in proper alignment and position, to within a tiny fraction of a wavelength over the four-kilometer lengths of both arms of the interferometers.
History of LIGO?
LIGO is a program with two observatories currently in the United States located in the cities of Hanford, Washington and Livingston, Louisiana. It was cofounded in 1992 by Kip Thorne and Ronald Drever of California Institute of Technology and Rainer Weiss of Massachusetts Institute of Technology, LIGO is a joint project between scientists at MIT and Caltech. The project cost of $365 million dollars and is the largest funding ever received for a project by the National Science Foundation (NSF).
Today LIGO is a growing research project with now recording well over 600 researchers working and analyzing data from LIGO.
پاورپوینت LIGO PRESENTATION PHYSICS 43