The Gravity Probe-B star-tracking telescope

Gwo, Dz‐Hung; Wang, S.; Bower, K.A.; Davidson, Donald E.; Ehrensberger, Paul; Huff, Lynn W.; Romero, E.; Sullivan, Mark; Triebes, K.; Lipa, J. A.

doi:10.1016/s0273-1177(03)90353-x

Cited by 31 publications

(26 citation statements)

References 3 publications

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“…Gravity Probe B was a satellite-based mission launched in April 2004, with the aim of measuring the space-time curvature near the Earth [43] by measuring minute changes in relative spin orientation of four gyroscopes in polar orbit around the earth [44]. Gravity Probe B took measurement data for 1 year (August 2004 to August 2005) and the data analysis of the mission was finally completed in 2011 [43].…”

Section: Gravity Probe Bmentioning

confidence: 99%

“…The experimental payload of the satellite was comprised of four gyroscopes and a star tracking telescope, all made of fused silica, mounted in a 2440 l superfluid helium Dewar operating at 1.8 K. When locked to the guide star, the telescope provided an inertial reference for the gyroscopes with an accuracy of 0.1 milli-arc-second (mas)/year [44]. To minimize errors, the gyroscopes and telescope were connected with massive blocks of fused silica.…”

Section: Gravity Probe Bmentioning

confidence: 99%

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Hydroxide catalysis bonding for astronomical instruments

Veggel

Killow

2014

Advanced Optical Technologies

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Hydroxide catalysis bonding (HCB) as a jointing technique has been under development for astronomical applications since ∼1998 (patented by D.-H. Gwo). It uses an aqueous hydroxide solution to form a chemical bond between oxide or oxidisable materials (e.g., SiO 2 , sapphire, silicon and SiC). It forms strong, extremely thin bonds, and is suitable for room temperature bonding, precision alignment, operation in ultra-low vacuum and down to temperatures of 2.5 K. It has been applied in the NASA satellite mission Gravity Probe B and in the ground-based gravitational wave (GW) detector GEO600. It will soon fly again on the ESA LISA Pathfinder mission and is currently being implemented in the Advanced LIGO and Virgo ground-based GW detectors. This technique is also of considerable interest for use in other astronomical fields and indeed more broadly, due to its desirable, and adjustable, combination of properties. This paper gives an overview of how HCB has been and can be applied in astronomical instruments, including an overview of the current literature on the properties of hydroxide catalysis bonds.

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Section: Gravity Probe Bmentioning

confidence: 99%

Section: Gravity Probe Bmentioning

confidence: 99%

Hydroxide catalysis bonding for astronomical instruments

Veggel

Killow

2014

Advanced Optical Technologies

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“…This technique was first created by Gwo for use in the Gravity Probe B satellite [36][37][38]. It has since been further developed for use in the construction of ground-and space-based gravitational wave detectors [13,32,33,[39][40][41].…”

Section: Hydroxide Catalysis Bondingmentioning

confidence: 99%

“…[36,38], when an alkali hydroxide bonding solution comes into contact with fused silica surfaces, a hydroxide catalysis bond is formed in three main steps: hydration (and etching), polymerization and dehydration. The bonds connecting the mirror suspension components in aLIGO and GEO600 used a sodium silicate bonding solution.…”

Section: A Chemistrymentioning

confidence: 99%

Mechanical loss of a hydroxide catalysis bond between sapphire substrates and its effect on the sensitivity of future gravitational wave detectors

et al. 2016

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Mechanical loss of a hydroxide catalysis bond between sapphire substrates and its effect on the sensitivity of future gravitational wave detectors. Physical Review D, 94(8), 082003. (doi:10.1103/PhysRevD.94.082003) This is the author's final accepted version.There may be differences between this version and the published version. Hydroxide catalysis bonds are low mechanical loss joints which are used in the fused silica mirror suspensions of current room temperature interferometric gravitational wave detectors, one of the techniques which was essential to allow the recent detection of gravitational radiation by LIGO. More sensitive detectors may require cryogenic techniques with sapphire as a candidate mirror and suspension material and thus hydroxide catalysis bonds are under consideration for jointing sapphire. This paper presents the first measurements of the mechanical loss of such a bond created between sapphire substrates and measured down to cryogenic temperatures. The mechanical loss is found to be 0.03 ± 0.01 at room temperature, decreasing to (3 ± 1) × 10 −4 at 20 K. The resulting thermal noise of the bonds on several possible mirror suspensions is presented.

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“…This bonding process is used to join surfaces through a hydroxide catalysed hydration and dehydration reaction [11,12]. It was first developed for use in the Gravity Probe B mission [13,14] and has been further developed for both ground and space based gravitational wave detectors [15][16][17][18]. Although the mechanical loss of a hydroxide catalysis bond is higher than that of bulk silica, it is at an acceptable level for advanced detector suspensions since the bond layer can be extremely thin (< 100 nm) [19,20].…”

Section: Introductionmentioning

confidence: 99%

Effect of heat treatment and aging on the mechanical loss and strength of hydroxide catalysis bonds between fused silica samples

et al. 2017

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Hydroxide catalysis bonds are used in the aLIGO gravitational wave detectors and are an essential technology within the mirror suspensions which allowed for detector sensitivities to be reached that enabled the first direct detections of gravitational waves. Methods aimed at further improving hydroxide catalysis bonds for future upgrades to these detectors, in order to increase detection rates and the number of detectable sources, are explored. Also, the effect on the bonds of an aLIGO suspension construction procedure involving heat, the fibre welding process, is investigated. Here we show that thermal treatments can be beneficial to improving some of the bond properties important to the mirror suspensions in interferometric gravitational wave detectors. It was found that heat treating bonds at 150 • C increases bond strength by a factor of approximately 1.5 and a combination of bond ageing and heat treatment of the optics at 150 • C reduces the mechanical loss of a bond from 0.10 to 0.05. It is also shown that current construction procedures do not reduce bond strength.

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The Gravity Probe-B star-tracking telescope

Cited by 31 publications

References 3 publications

Hydroxide catalysis bonding for astronomical instruments

Hydroxide catalysis bonding for astronomical instruments

Mechanical loss of a hydroxide catalysis bond between sapphire substrates and its effect on the sensitivity of future gravitational wave detectors

Effect of heat treatment and aging on the mechanical loss and strength of hydroxide catalysis bonds between fused silica samples

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