Two multi-wavelength interferometers for large-scale surveying

Sauthoff, Anni; Köchert, Paul; Prellinger, Günther; Meyer, Tobias; Pilarski, Frank; Weinrich, Stephanie; Schmaljohann, Frank; Guillory, Joffray; Truong, Daniel; Silbermann, Jakob; Kallio, Ulla; Jokela, Jorma; Pollinger, Florian

doi:10.4995/jisdm2022.2022.13635

Cited by 2 publications

(2 citation statements)

References 27 publications

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“…But the accuracy requirements on the optical measurement are extremely challenging (Röse et al 2021). Both systems, TeleYAG-II and Absolute 3D, are discussed in more depth by (Sauthoff et al 2022).…”

Section: Multi-wavelength Interferometrymentioning

confidence: 99%

The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy

et al. 2023

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We provide a survey on the joint European research project “GeoMetre”, which explores novel technologies and their inclusion to existing surveying strategies to improve the traceability of geodetic reference frames to the SI definition of the metre. This work includes the development of novel distance meters with a range of up to 5 km, the realisation of optical multilateration systems for large structure monitoring at an operation distance of 50 m and beyond, and a novel strategy for GNSS-based distance determination. Different methods for refractivity compensation, based on classical sensors, on dispersion, on spectroscopic thermometry, and on the speed of sound to reduce the meteorological uncertainties in precise distance measurements, are developed further and characterised. These systems are validated at and applied to the novel European standard baseline EURO5000 at the Pieniny Kippen Belt, Poland, which was completely refurbished and intensely studied in this project. We use our novel instruments for a reduced uncertainty of the scale in the surveillance networks solutions for local tie measurements at space-geodetic co-location stations. We also investigate novel approaches like close-range photogrammetry to reference point determination of space-geodetic telescopes. Finally, we also investigate the inclusion of the local gravity field to consider the deviations of the vertical in the data analysis and to reduce the uncertainty of coordinate transformations in this complex problem.

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Section: Multi-wavelength Interferometrymentioning

confidence: 99%

The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy

et al. 2023

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“…More recently, several types of instruments have implemented this technique. For example, we can mention the development of a homodyne interferometer [20], or the TeleYAG and TeleYAG II multi-wavelength heterodyne interferometers which allow the measurement of absolute distances [24,25]. The latter use frequency-doubled Nd:YAG lasers that provide wavelengths at 1064 nm and 532 nm for a factor A of about 65 (phase index).…”

Section: Introductionmentioning

confidence: 99%

A sub-millimetre two-wavelength EDM that compensates the air refractive index: uncertainty and measurements up to 5 km

Guillory,

Truong,

Wallerand

et al. 2023

Meas. Sci. Technol.

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Distance measurements over several kilometres with a sub-millimetre uncertainty are required for deformation monitoring in fields such as geodesy or civil engineering where well-controlled scale is critical. This paper presents a two-wavelength electro-optical distance meter (EDM) capable of such measurements and traceable to the SI (Système International d’unités). It is based on simultaneous measurements of optical path lengths, at two wavelengths, one at 780 nm and the other at 1560 nm, the dispersion between the two wavelengths allowing real-time compensation of the air refractive index along the optical paths. The uncertainty budget of this EDM has been established, taking into account both the telemetric and the mechanical contributions. One of the main sources of errors is crosstalk, which originates mainly from the optical splitters acting as circulators and becomes more pronounced for lower received powers over longer distances. For signal-to-crosstalk ratios (SCRs) higher than 60 dB, the instrumental uncertainty in the air-index compensated distance was assessed to be 320 µm (k = 1). In the field, two distance measurements, one over 2.6 km, the other over 5.4 km, were carried out over a period of up to 6 days, and for a temperature and pressure varying by as much as 10 °C and 17 hPa. For each distance, the standard deviation of the Gaussian fit of the experimental points was less than 250 µm. This level of refractivity compensation demonstrates that the developed instrument works properly. In addition, standard deviations lower than 140 µm were achieved for displacement measurements at distances around 2.6 km and 5.4 km. All these results were obtained for SCRs higher than 60 dB. Finally, solutions are proposed for mitigating the effect of high crosstalk values on instrumental uncertainty.

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Two multi-wavelength interferometers for large-scale surveying

Cited by 2 publications

References 27 publications

The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy

The European GeoMetre project: developing enhanced large-scale dimensional metrology for geodesy

A sub-millimetre two-wavelength EDM that compensates the air refractive index: uncertainty and measurements up to 5 km

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