Compact portable laser system for mobile cold atom gravimeters

Abstract

We have designed and realized a compact portable laser system for high-sensitivity mobile cold atom interferometers. The laser system is mounted on a single module with dimensions of 45 cm×45 cm×16 cm and emits lights directly on up to 13 fiber ports for a two-dimensional magneto-optical trap, atom fountain, Raman transition, and normalized detection. A double-sided optical structure and mounts without kinematic adjustment are designed to achieve high-level integration and stability. The laser system is applied to a mobile atom gravimeter and achieves a sensitivity of 28 μGal/Hz. Experiencing 1200-km-long truck transportation, the laser system could be restored to good operating status without internal realignment.

High-accuracy inertial measurements with cold-atom sensors

“…The five optical frequencies needed to perform a coldatom inertial sensor are represented in figure 3, for 87 Rb interferometers based on Raman transitions. A variety of different laser systems have been developed and published, with different number of lasers, ranging from five to only one, with designs constrained by the size, the final application, the measurement environment conditions and the evolution of technologies [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] . Figure 4 displays a compact free space optical system and a complete architecture of a fibered optical bench which reached a Technology Readiness Level (TRL) of 4 (Ref.…”

“…59 ). Since then, the technology of atomic gravity sensors has considerably grown in maturity, as assessed by some major achievements, such as i) the participation since 2009 to CIPM Key Comparisons (KC) and Euramet comparisons of absolute gravimeters [60][61][62] , in 2017, even if not included in the 3 rd KC 63 , four atom gravimeters developed in China 39,[64][65][66] have participated to the associated pilot study; ii) the demonstration of on board measurements, in a ship 67 and a plane 68 and iii) the industrial development and commercial product offer of atom gravimeters at a competitive level of performance 69 . In total, about 30 research groups and private companies are today working on the development of atomic gravity sensors.…”

“…To address wider applications, engineering and simplification efforts in the sensors or its key subsystems are made in order to allow performing measurements in more aggressive environments 28,32,37,39,41,44,69,[103][104][105][106] . Operation of gravity sensors on board a ship 67 , and more recently in an aircraft 68 , has been demonstrated, and gravity mapping have been performed in both cases, showing improved repeatability and lower uncertainties compared to classical marine gravimeters.…”

Robot-assisted, source-camera-coupled multi-view broadband imagers for ubiquitous sensing platform

“…To this end, several studies have investigated diverse systems, photo-sources and photo-imagers including functional unmanned remote sensing robotics 17 , 18 , high-usability miniature photo-sources 19 , 20 , flexible multi-view stereoscopic photo-imagers 21 , 22 and highly efficient uncooled broadband photo-absorbent materials 23 , 24 . In a related study, Yang et al developed the thermo-phototronic effect 25 , which is based on the combination of thermoelectric effect with the photoelectric effect in some semiconductor materials 26 – 29 .…”

Gravity surveys using a mobile atom interferometer

“…Transportable atomic gravimeters are being developed toward metrology ( 17 – 22 ), airborne sensing ( 23 ), shipborne surveys ( 24 ), and field applications ( 25 – 29 ). They typically reach sensitivities around 5 to 100 μGalileo (μGal)/Hz (1 μGal = 10 nm/s 2 ) in the laboratory ( 17 – 21 , 25 , 27 ), but the only atomic gravimeter used in gravity surveys achieves a precision of only ~1 mGal on a ship ( 24 ). Meanwhile, precise mobile gravimetry is valuable in broad areas.…”