High accuracy magnetic measurements with the ASQ-81 scalar magnetometer

Author

Bourgeois, Brian S. ; Ross, Jerry H. ; Avera, Will

Author_Institution

US Naval Oceanogr. & Atmos. Res. Lab., Stennis Space Center, MS, USA

Volume

40

Issue

4

fYear

1991

fDate

8/1/1991 12:00:00 AM

Firstpage

784

Lastpage

787

Abstract

The Texas Instruments´ ASQ-81 scalar magnetometer provides high-resolution total field magnetic measurements. It uses an optically pumped metastable helium gas detector that has a range of 23000 to 75000 gammas (1 gamma=1 nT) and a 0.016 gamma peak-to-peak noise level. The authors first discuss the theory of operation for the ASQ-81 helium, optically pumped, controlled-oscillator type scalar magnetometer. Following this discussion, the measurement error induced by high sampling rates for a controlled oscillator magnetometer is quantized. A scheme for making frequency measurements that are free of this induced error by synchronizing the measurements with the modulation frequency of the controlled oscillator is presented. The authors describe the circuitry and techniques required to reduce the measurement error to less than the instrument noise level

Keywords

geophysical equipment; magnetic field measurement; magnetometers; measurement errors; 23000 to 75000 gamma; ASQ-81 scalar magnetometer; GASS; He lamp; IR detector; Navy; controlled-oscillator; frequency measurements; geophysical equipment; measurement error; metastable He; modulation frequency; optically pumped He gas detector; sampling rates; scalar magnetometer; total field magnetic measurements; Helium; Instruments; Magnetic variables measurement; Magnetometers; Measurement errors; Noise level; Optical control; Optical noise; Optical pumping; Oscillators;

fLanguage

English

Journal_Title

Instrumentation and Measurement, IEEE Transactions on

Publisher

ieee

ISSN

0018-9456

Type

jour

DOI

10.1109/19.85356

Filename

85356