Pico meter metrology for the GAIA mission

Meijer, E.A.; Nijenhuis, J.N.; Vink, Ramon; Kamphues, Fred; Gielesen, W.L.M.; Coatantiec, Claude

doi:10.1117/12.789339

Cited by 4 publications

(3 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This material combination was proved to offer the needed dimensional stability at the nanometer level at room temperature. [7] The Global Astrometric Interferometer for Astrophysics [8] (GAIA) mission is another example where dimensional stability is critical: its mirrors and support are made of silicon carbide structures and need stabilities at the picometer and picoradian level in a cold environment [9,10] (%100 K). The future spaceborne gravitational wave detector, LISA, will also require extremely stable optical assemblies such as optical benches and telescopes.…”

Section: Introductionmentioning

confidence: 99%

Laser-dilatometer calibration using a single-crystal silicon sample

Hamann

Sanjuán

Spannagel

et al. 2019

International Journal of Optomechatronics

View full text Add to dashboard Cite

Marginal changes in geometrical dimensions due to temperature changes affect the performance of optical instruments. Highly dimensionally stable materials can minimize these effects since they offer low coefficients of thermal expansion (CTE). Our dilatometer, based on heterodyne interferometry, is able to determine the CTE in 10 À8 K À1 range. Here, we present the improved interferometer performance using angular measurements via differential wavefront sensing to correct for tilt-to-length coupling. The setup was tested by measuring the CTE of a single-crystal silicon at 285 K. Results are in good agreement with the reported values and show a bias of less than 1%.

show abstract

Section: Introductionmentioning

confidence: 99%

Laser-dilatometer calibration using a single-crystal silicon sample

Hamann

Sanjuán

Spannagel

et al. 2019

International Journal of Optomechatronics

View full text Add to dashboard Cite

show abstract

“…Both the machinability and the roughness development during the etching process plays an important role in the fabrication of special SiC mirrors of the basic angle monitoring opto-mechanical assembly (BAM-OMA) in the GAIA space telescope mission which is the main objective in our recent research concerning SiC. [6]…”

Section: Introductionmentioning

confidence: 99%

Reactive Plasma Jet High‐Rate Etching of SiC

Eichentopf

Böhm

Meister

et al. 2009

Plasma Processes & Polymers

View full text Add to dashboard Cite

The material removal of SiC utilizing a 2.45 GHz microwave‐driven plasma jet source in comparison with a 13.56 MHz RF excited plasma jet source at atmospheric pressure has been investigated. A coaxial nozzle with a central tube for helium, CF4 and O2 feeding the plasma and the outer ring‐shaped nozzle for N2 to shield the plasma jet from the surrounding air is applied. Additionally an O2 gas flow is provided and its effect on the etching rate is discussed for varied [CF4]/[O2] ratios. By optimizing the ratio of CF4 and O2 gas flow an improvement in etching rates and a change in surface roughness have been found. An increase of the etching rate with a decrease of the CF4 ratio has been detected for both jets. The etching rate of the microwave excited jet has been improved additionally by heating the SiC sample up to 350 °C.

show abstract

“…This places very stringent demands on the stability of the instrument and especially of the basic angle between the two viewing directions. Passive stabilization of the instrument guarantees that the global parallax zero point error is less than 3.5 μas, but Direct distance determination using parallax in addition the interferometric Basic Angle Monitor (Meijer et al 2008) will allow elimination of much smaller variations in the data analysis, reducing the zero point error to below 0.1 μas. Statistically, the Gaia parallaxes should therefore be meaningful even at extragalactic distances.…”

Section: Absolute Parallaxes: Hipparcos and Gaiamentioning

confidence: 99%

Direct distance determination using parallax: Techniques, promises and limitations

Lindegren

2012

Proc. IAU

View full text Add to dashboard Cite

Abstract. Determination of trigonometric parallaxes is one of the very few direct methods available for measuring cosmic distances, and the only one capable of reaching beyond the Solar System. It is fundamental both to determine the intrinsic properties of astrophysical objects and as the first step on the cosmic distance ladder. Steady improvements of instruments and techniques have extended the applicability of the parallax method to ever greater distances. However, it is not correct to say that the method is independent of physical assumptions. This review covers ground-based optical techniques, from Bessel's time to the present, as well as space observations and radio interferometry. Some emphasis is put on the physical limitations of the method, in particular its sensitivity to source structure and photocentric variability on different timescales.Keywords. astrometry, stars: distances, solar neighborhood, Galaxy: general What is parallax?If the stars were fixed in space, relative to the Sun, each would appear to describe a small ellipse as seen by an observer on the Earth. This parallax ellipse mirrors the Earth's orbit as seen from the star: the semi-major axis equals the angle subtended by the astronomical unit (au) at the distance of the star: that is the parallax ; the axis ratio equals sin β, where β is the ecliptic latitude of the star; and the phase of the parallax motion varies with the ecliptic longitude of the star. Real stars are in motion, however, which usually can be modelled quite accurately over several years as a constant angular velocity or proper motion, μ. Combining the two effects, it is found that the variation in any angular coordinate θ (such as α or δ) can be modelled as( 1.1) where θ 0 is the coordinate at reference time t 0 and F θ (t, α, δ) is a known function representing the projection of the unit parallax ellipse in the measurement direction, i.e. along θ. Note that F θ depends on the position of the star as well as on time because of the varying shape and phase of the parallax ellipse across the celestial sphere. From a series of accurate positional measurements, covering θ(t) over the course of at least one year, it is in principle trivial to determine the three model parameters θ 0 , μ and by least-squares fitting of Eq.(1

show abstract

Pico meter metrology for the GAIA mission

Cited by 4 publications

References 4 publications

Laser-dilatometer calibration using a single-crystal silicon sample

Laser-dilatometer calibration using a single-crystal silicon sample

Reactive Plasma Jet High‐Rate Etching of SiC

Direct distance determination using parallax: Techniques, promises and limitations

Contact Info

Product

Resources

About