Projects per year
Abstract
A low-noise source of illumination is described for shadow-sensors having a displacement sensitivity of (69 ± 13) picometres (rms)/√Hz, at 500 Hz, over a measuring span of ±0.1 mm. These sensors were designed to detect ‘Violin-Mode’ resonances in the suspension fibres of the test-masses/mirrors for the Advanced LIGO (Laser Interferometer Gravitational wave Observatory) gravitational wave detectors. The source of illumination (emitter) described here used a single column of 8 × miniature Near InfraRed LEDs (λ = 890 nm). These emitters cast the shadows of 400 µm diameter fused silica suspension fibres onto their complementary shadow-displacement detectors, located at a distance of 74 fibre diameters (29.6 mm) behind the axes of the fibres themselves. Violin-Mode vibrations of each fibre were sensed as differential AC photocurrents in the corresponding ‘split-photodiode’ detector. This paper describes the design, construction, noise analysis, and measures that were taken in the conception of the emitters, in order to produce high-contrast shadows at such distant detectors. In this way it proved possible to obtain, simultaneously, a very high transfer sensitivity to Violin-Mode vibration of the fibres, and a very low level of detection noise—close to the fundamental shot noise limit—whilst remaining within the constraints of this simple design of emitter. The shadow detector is described in an accompanying paper.
Original language | English |
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Article number | 125111 |
Number of pages | 12 |
Journal | Measurement Science and Technology |
Volume | 25 |
Issue number | 12 |
DOIs | |
Publication status | Published - 7 Nov 2014 |
Keywords
- LED arrays
- shadow displacement sensors
- gravitational wave detectors
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Dive into the research topics of 'A source of illumination for low-noise 'Violin-Mode' shadow sensors, intended for use in interferometric gravitational wave detectors'. Together they form a unique fingerprint.Projects
- 3 Finished
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Investigations In Gravitational Radiation: Oct 2010 To Mar 2012
STFC Science and Technology Facilities Council
1/10/10 → 31/03/12
Project: Research
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Gravitational Radiation Instrumentation
PPARC (Particle Physics and Astronomy Research Council)
1/07/10 → 31/12/18
Project: Research
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Investigations in Gravitational Radiation
PPARC (Particle Physics and Astronomy Research Council)
1/10/05 → 30/09/07
Project: Research