LF13479A
- The quest to measure exceedingly small motions of test masses for gravitational wave detectors has, over the past 40 years, led to the development of successive generations of ever more sensitive instruments limited by the laws of nature. Physicists studying kilometer scale laser interferometer gravitational wave detectors have turned a problem - triple resonance of two light fields with a single sound field - into a new instrument. They have experimentally shown that the instrument can measure a tiny vibration as small as a thousandth of the diameter of the nucleus of a gold atom...about one part in 10 to the power of 17 of a meter! They show that simple improvements can make the instrument 1000-fold more sensitive.
The new instrument operates by shining laser light onto a flexible mirror. When the light reflects off the mirror, the mirror recoils and the tiny recoil is enough to convert the light into a new light beam of a slightly different colour, and in a pattern that allows it to build up by resonance as it reflects back and forth between the flexible mirror and a second mirror. This resonance enhances the conversion of the vibration to the new light. By measuring the intensity of the new light, the mirror vibration is measured to extreme accuracy. The trick in making this deceptively simple concept work is the tuning of the resonance for the new light, which the team achieves by using a secondary laser to precisely deform one of the mirrors.
In a slight variation the same instrument can amplify radio waves and turn these into light, or measure tiny magnetic fields down to a millionth of the strength of the earth’s magnetic field.
The researchers plan to make a sensor for airborne detection of magnetic minerals, as well as tiny devices usable in space for measuring the composition of asteroids that could be mined and used in future space exploration.
