Available Technology

COMPACT ATOMIC MAGNETOMETER AND GYROSCOPE BASED ON A DIVERGING LASER BEAM

Gyroscopes sense rotation. In combination with magnetometers, gyroscopes are used in inertial navigation and platform stabilization applications. Our invention is the first to demonstrate simultaneous measurement of rotation, rotation angle and acceleration with a single source of atoms. Multiple addressable markets exist based on the combined performance of the magnetometer and gyroscope in inertial navigation systems (INS). A variety of magnetometer/ gyroscope combinations exist but are expensive. The compact atomic gyroscope enables multitasking measurement capabilities.

The problem was that signal strength and data acquisition speed needed to be increased to enable increased sensitivity measurements. In addition, a smaller design was needed for use in compact systems that could be used in the field. This invention solves these issues. The design can be implemented with a micro machined alkali vapor cell and light from a single semiconductor laser. A small modification to the cell contents and excitation geometry allows for use as a gyroscope. Atomic magnetometers are scalar sensors, which means they sense the magnitude of the magnetic field, rather than the projection along one spatial direction. This is particularly important for applications on moving platforms since platform motion adds considerable noise to a vector sensor as the angle between the field and the sensor axis changes. Multiple applications of gyroscopes exist within INS as well as multiple end-use applications including manned aircraft, automotive and autonomous vehicles.

The figure below (100) illustrates a schematic of an apparatus in which one embodiment of the present invention can be implemented. The parts shown are:
70 magnetic field
1 magnetic field to be sensed
2 atoms
3 incident light field
4 RF coils
20 semiconductor laser
30 optics
40 a set of radio-frequency (RF) coils
50 alkali vapor cell
60 photodetectors

Abstract: 

An atomic magnetometer that simultaneously achieves high sensitivity, simple fabrication and small size. This design is based on a diverging (or converging) beam of light that passes through an alkali atom vapor cell and that contains a distribution of beam propagation vectors. The existence of more than one propagation direction permits longitudinal optical pumping of atomic system and simultaneous detection of the transverse atomic polarization. The design could be implemented with a micro machined alkali vapor cell and light from a single semiconductor laser. A small modification to the cell contents and excitation geometry allows for use as a gyroscope.

Benefits: 

The NIST gyroscope can also simultaneously measure rotation and acceleration. A combination gyro/accelerometer enables navigation by "dead reckoning," without reference to external landmarks or stars.

Inventors: 
John Ktiching, Elizabeth Donley, Eleanor Hodby, Andrei Shkel, E. Jesper Eklund
Patent Number: 
7,872,473
Technology Type(s): 
Atomic Physics, Manufacturing, Precision Measurement
Internal Laboratory Ref #: 
07-017
Patent Issue Date: 
January 11, 2018
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