A system method and computer-readable medium for correcting measurements obtained by a down hole tool for residual measurement errors is disclosed. A down hole tool having at least two directional field sensors is disposed in a borehole. The at least two directional sensors are substantially orthogonal to each other and to a longitudinal axis of the down hole tool. Measurements are obtained from the at least two directional sensors during rotation of the tool by at least 360 degrees around the longitudinal axis of the tool. Residual measurement errors are determined for the obtained measurements, and a quality level of the determined residual measurement errors selected. The determined residual measurement errors are applied to the obtained measurements when the determined residual measurement errors are consistent with the selected quality level. In various embodiments, the residual measurement errors are reduced from a first value that does not match the selected quality level to a second value that are consistent with the selected quality level.

An airborne gravity-based transducer is disclosed as two embodiments with similar physical structures but different operating principles. The first design includes a particle acting as an active interface characterized by internal vibrations relating to its de Broglie wave, a resonant cavity for trapping the particle, and a phonon-wave source wherein the de Broglie and phonon waves interact over a junction area. In the second design, mechanical displacements between the transducer elements can be monitored through electromechanical transduction. Both designs include a power source and a biasing circuit for producing an electrical current across the junction, and a sensing system for measuring voltage. Both designs are capable of cancelling slowly-varying gravitational acceleration due to dynamic interaction in motion with the gravitational field and responding to small-scale gravity anomalies. The transducer can be utilized in hydrocarbon exploration to provide information on areas conducive to fluid entrapment in the sedimentary column.

An optomechanical inertial reference minor combines an optomechanical resonator with a reflector that serves as an inertial reference for an atom interferometer. The optomechanical resonator is optically monitored to obtain a first inertial measurement of the reflector that features high bandwidth and high dynamic range. The atom interferometer generates a second inertial measurement of the reflector that features high accuracy and stability. The second inertial measurement corrects for drift of the first inertial measurement, thereby resulting in a single inertial measurement of the reflector having high bandwidth, high dynamic range, excellent long-term stability, and high accuracy. The reflector may be bonded to the resonator, or formed directly onto a test mass of the resonator. With a volume of less than one cubic centimeter, the optomechanical inertial reference minor is particularly advantageous for portable atomic-based sensors and systems.

An inertial navigation system (INS) device includes three or more atomic interferometer inertial sensors, three or more atomic interferometer gravity gradiometers, and a processor. Three or more atomic interferometer inertial sensors obtain raw inertial measurements for three or more components of linear acceleration and three or more components of rotation. Three or more atomic interferometer gravity gradiometers obtain raw measurements for three or more components of the gravity gradient tensor. The processor is configured to determine position using the raw inertial measurements and the raw gravity gradient measurements.

An inertial navigation system (INS) device includes three or more atomic interferometer inertial sensors, three or more atomic interferometer gravity gradiometers, and a processor. Three or more atomic interferometer inertial sensors obtain raw inertial measurements for three or more components of linear acceleration and three or more components of rotation. Three or more atomic interferometer gravity gradiometers obtain raw measurements for three or more components of the gravity gradient tensor. The processor is configured to determine position using the raw inertial measurements and the raw gravity gradient measurements.

An absolute gravimeter and a measurement method based on vacuum optical tweezers. The micro-nano particle releasing device is equipped with micro-nano particles, and is located above laser optical tweezers, and the laser optical tweezers have two capturing beams which pass through the respective convergent lenses and then converge at an intersection. An area where the intersection is located serves as an optical trap capturing region, and the micro-nano particles are stably captured by the two capturing beams in the optical trap capturing region. The optical interferometer is electrically connected to the signal processing device, the optical interferometer measures a displacement of the micro-nano particles in real time at the beginning of a free fall process from the optical trap capturing region and sends the displacement signal to the signal processing device. The signal processing device obtains a measured value of an absolute gravitational acceleration.

A method and apparatus for for sensing a change in an acceleration gradient δa(t) between two gravity fields a.sub.1(t) and a.sub.2(t) respectively sensed by the first and second proof masses, the first and second proof masses either being coupled only to a first resonator or being individually coupled to first and second resonators, the first resonator generating, in use, a signal at a frequency f.sub.D which is applied said second resonator, the second resonator being driven, in use, into a non-linear state corresponding to a modal resonant frequency f.sub.Θ wherein it generates a comb of frequencies each tooth of which is separated from each other by a frequency Δ which is frequency-wise proportional a frequency difference between f.sub.D and f.sub.Θ and also proportional to the change in said acceleration gradient δa(t), circuitry for selecting an n.sup.th tooth in said comb of frequencies where the frequency of the n.sup.th tooth is equal to f.sub.D+nΔ, circuitry for detecting a change in the frequency of the n.sup.th tooth and for generating a signal that is proportional to n times the change in an acceleration gradient δa(t).

A method and apparatus for for sensing a change in an acceleration gradient δa(t) between two gravity fields a.sub.1(t) and a.sub.2(t) respectively sensed by the first and second proof masses, the first and second proof masses either being coupled only to a first resonator or being individually coupled to first and second resonators, the first resonator generating, in use, a signal at a frequency f.sub.D which is applied said second resonator, the second resonator being driven, in use, into a non-linear state corresponding to a modal resonant frequency f.sub.Θ wherein it generates a comb of frequencies each tooth of which is separated from each other by a frequency Δ which is frequency-wise proportional a frequency difference between f.sub.D and f.sub.Θ and also proportional to the change in said acceleration gradient δa(t), circuitry for selecting an n.sup.th tooth in said comb of frequencies where the frequency of the n.sup.th tooth is equal to f.sub.D+nΔ, circuitry for detecting a change in the frequency of the n.sup.th tooth and for generating a signal that is proportional to n times the change in an acceleration gradient δa(t).

The present application discloses a dead-zone-free cold atom interferometer with a high frequency output. The interferometer includes: a three-dimensional magneto-optical trap, wherein a predetermined angle is formed between the first group of light sources and an atomic beam path, the first group of optical stops are arranged at edges of the first group of light sources and downstream of the atomic beam path, the first group of optical stops block laser light emitted from the first group of light sources, the second group of light sources are orthogonally arranged with respect to the first group of light sources, the second group of optical stops are arranged at edges of the second group of light sources and downstream of the atomic beam path, and the second group of optical stops block laser light emitted from the second group of light sources.

Examples are directed toward systems and methods relating to security screening. For example, a screening system includes a sensor array to sense a gravitational field caused by an item, and a conveyor to convey the item through sensing positions for scanning by the sensor array. A controller acquires weight measurement information from sensor elements, and gravitational measurement information from the sensor array. The conveyor incrementally advances the item through additional sensing positions to acquire weight measurement information and gravitational measurement information. The controller performs tomographic reconstruction to generate a tomographic image of the item, using a generated weight map as a static weight input vector and using a generated mass map as a static mass input vector for the tomographic reconstruction.