Optically-pumped magnetometer (OPM) with an OPM connector that mitigates electrostatic discharge (ESD) and stores OPM operational data

An Optically Pumped Magnetometer (OPM) system is configured to characterize a magnetic field. The OPM system comprises an OPM sensor that is coupled to an OPM cable that is coupled to an OPM connector that is detachably coupled to an OPM controller. The OPM connector stores OPM operational data. The OPM controller reads the OPM operational data when the OPM connector is coupled to an OPM controller. The OPM controller generates sensor control signals based on the OPM operational data and transfers the control signals to the OPM sensor. The OPM sensors characterize the magnetic field in response to the sensor control signals and transfer output signals that characterize the magnetic field to the OPM controller. The OPM controller models the magnetic field based on the output signals and transfers new OPM operational data to OPM connector. The OPM connector stores the new OPM operational data in the memory.

TECHNICAL BACKGROUND

Optically-Pumped Magnetometers (OPMs) detect and characterize target magnetic fields. The OPM has OPM sensors to detect and characterize the target magnetic fields. The OPM sensors transfer corresponding OPM signals over OPM cables and OPM connectors to an OPM controller. The OPM controller processes the OPM signals to build a model of the target magnetic field. An individual OPM sensor, OPM cable, and OPM connector are coupled together in a permanent configuration. The OPM connectors are coupled to the OPM controller through a detachable interface like a pins and sockets. Unfortunately, the OPM cables and the OPM connectors store unwanted energy and deliver undesirable Electrostatic Discharge (ESD) to the OPM sensors. The ESD damages lasers and other delicate electronics in the OPM sensors. Moreover, the OPM sensors and the OPM controller are modular, and different OPM sensors may be used by different OPM controllers or controller cards. The modularity of the OPM sensors and the OPM controllers causes the operator to externally track OPM sensor data to customize the performance of the OPM sensors when different OPM sensors are coupled to different OPM controllers.

TECHNICAL OVERVIEW

An Optically Pumped Magnetometer (OPM) system is configured to characterize a magnetic field. The OPM system comprises an OPM sensor that is coupled to an OPM cable that is coupled to an OPM connector that is detachably coupled to an OPM controller. The OPM connector stores OPM operational data in a memory. The OPM controller reads the OPM operational data from the memory in the OPM connector when the OPM connector is coupled to an OPM controller. The OPM controller generates sensor control signals based on the OPM operational data and transfers the control signals to the OPM sensor over the OPM connector and the OPM cable. The OPM sensors characterize the magnetic field in response to the sensor control signals and transfer output signals that characterize the magnetic field to the OPM controller over the OPM cable and the OPM connector. The OPM controller models the magnetic field based on the output signals and transfers new OPM operational data to OPM connector. The OPM connector stores the new OPM operational data in the memory.

TECHNICAL DESCRIPTION

FIG.1illustrates Optically-Pumped Magnetometer Magnetoencephalography (OPM MEG) system100. OPM MEG system100comprises target101, OPM sensors111, OPM cables121, OPM connectors131, and OPM controller141. OPM MEG system100characterizes a magnetic field emitted by target101. OPM sensors111are coupled to OPM cables121that are coupled to OPM connector131. OPM connectors131are detachably coupled to OPM controller141. OPM connectors131are shown in an uncoupled state, but OPM connectors131are coupled to OPM controller141during operation. For example, a human may plug a plastic housing with internal metallic wiring into a connector socket of a card in OPM controller141.

Various examples of network operation and configuration are described herein. In some examples, relays in OPM connectors131connect metallic links in OPM connectors131that are coupled to lasers in OPM sensors111. The metallic links may comprise switches, spring-loaded contacts, transistors, and/or other types of metallic interfaces. OPM connectors131detachably couple to OPM controller141. The relays in OPM connectors131receive control signals from OPM controller141when OPM connectors131are coupled to OPM controller141. The relays disconnect the metallic links in OPM connectors131in response to the control signal from the OPM controller141. For example, the relays may disconnect the metallic links in OPM connectors131in response to the insertion of OPM connectors131into OPM controller141. OPM connectors131store OPM operational data in their memory. OPM controller141reads the OPM operational data from the memory in OPM connectors131when OPM connectors131are coupled to OPM controller141. OPM controller141generates sensor control signals based on the OPM operational data. OPM controller141transfers the control signals to OPM sensors111over OPM connectors131and OPM cables121. OPM sensors111characterize the magnetic field in response to the sensor control signals. OPM sensors111transfer output signals that characterize the magnetic field to OPM controller141over OPM cables121and OPM connectors131. OPM controller141models the magnetic field based on the output signals. For example, OPM controller141may ingest the output signals from OPM sensors111and model the magnetic field at the location of OPM sensors111and transfer the model to downstream systems. For example, OPM controller141may build and maintain a three-dimensional model of the target magnetic field. OPM controller141transfers new OPM operational data to OPM connectors131. OPM connectors131store the new OPM operational data in their memory. OPM connectors131detach from OPM controller141. The relays in OPM connectors131connect the metallic links that are coupled to the laser in OPM sensors111in response to the loss of the control signal from OPM controller141. For example, the relays may connect the metallic links in OPM connectors131in response to the decoupling of OPM connectors131from OPM controller141.

Advantageously, OPM connectors131store OPM operational data to reduce or eliminate external data that is used by OPM controller141to customize the operation of OPM sensors111. Moreover, OPM connectors131mitigate Electrostatic Discharge (ESD) from developing and reaching OPM sensor111by shorting metallic links when OPM sensors111are not operating.

Target101is depicted as a human being, however, target101may comprises any magnetic field source. Target101emits magnetic waves that form a target magnetic field. OPM sensors111comprises lasers, coils, vapor cells, photo detectors, heaters, bus circuitry, and the like. OPM sensors111are positioned in the target magnetic field and detect the target magnetic field to generate signals that individually characterize the target magnetic field. OPM cables121comprise sheathed metal wires that transfer signaling between OPM sensors111and OPM connectors131. OPM connectors131comprise relays, memory, metallic interfaces, bus circuitry, and the like. OPM controller141comprises microprocessors, software, memories, metallic interfaces, bus circuitry, and the like. The microprocessors comprise Field Programmable Gate Arrays (FPGAs), Digital Signal Processors (DSP), Application-Specific Integrated Circuits (ASIC), and/or the like. The memories comprise flash circuitry, disk drives, and/or the like. The memories store software like operating systems, sensor applications, and magnetic field processing functions. The microprocessors retrieve the software from the memories and execute the software to drive the operation of OPM MEG system100as described herein.

FIG.2illustrates an exemplary operation of OPM MEG system100to characterize the magnetic field. The operation may differ in other examples. A relay in one of OPM connectors131connects two metallic links that are coupled to a laser in a corresponding one of OPM sensors111(201). The corresponding one of OPM sensors111is coupled to the one of OPM connectors131over a cable of OPM cables121. If the one of OPM connectors131is not attached to OPM controller141, the relay continues to connect the two metallic links. If the one of OPM connectors131is attach to OPM controller141, the process proceeds to step202. The relay in the one of OPM connectors131receives control signals from OPM controller when the one of the OPM connectors131is coupled to OPM controller141(202).

In response to the control signal from OPM controller141, the relay in the one of the OPM connectors131disconnects the two metallic links in the OPM connector that are coupled to the laser in the OPM sensor (203). Disconnecting the two metallic links allows OPM controller141to communicate with the corresponding one of OPM sensors111. If the one of OPM connectors131remains connected to OPM controller141or does not receive any new control signaling, then the relay continues to disconnect the two metallic links. If the one of OPM connectors131detaches from OPM controller141or receives different control signals, then the operation proceeds to step204. The relay in the one of OPM connectors131connects the two metallic links in response to the detachment and/or the different control signal (204). For example, the relay may connect to the two metallic links to short the metallic links to prevent the buildup of Electrostatic Discharge (ESD) in the one of the OPM connectors131when it is disconnected. For example, the relay may connect to the two metallic links to short the metallic links to prevent the buildup of ESD in the one of the OPM connectors131when the relay receives a control signal from OPM connector141that directs the relay to connect the two metallic links.

FIG.3illustrates another exemplary operation of OPM MEG system101to characterize the magnetic field. The operation may differ in other examples. OPM connectors131store OPM operational data in their memory for corresponding ones of OPM sensors111. For example, an OPM connector of OPM connectors131may store OPM operational data for an OPM sensor of OPM sensors111that it is connected to over one of OPM cables121. OPM controller141reads the OPM operational data for OPM sensors141from OPM connectors131. OPM controller141generates sensor control signals for OPM sensors111based on the OPM operational data. OPM controller141transfers the sensor control signals to OPM sensors111over OPM connectors131and OPM cables121. In response to the control signals, OPM sensors111measure and characterize the magnetic field emitted by target101. OPM sensors111transfer output signals that indicate the measured magnetic field over OPM cables121and OPM connectors131to OPM controller141. OPM controller141models the magnetic field of target101based on the output signals. OPM controller141generates new OPM operational data for OPM sensors111based on the output signals. OPM controller141transfers the new OPM operational data to OPM connectors131. OPM connectors131store the new OPM operational data for OPM sensors111in memory.

FIG.4illustrates Optically-Pumped Magnetometer Magnetoencephalography (OPM MEG) system400to characterize a magnetic field. OPM MEG system400comprises an example of OPM MEG system100, however OPM MEG system100may differ. OPM MEG system comprises target401, OPM sensor411, OPM cable421, OPM connector431and OPM controller441. Target401is magnetically linked to OPM sensor411. OPM sensor411is metallically linked to OPM cable421which is metallically linked to OPM connector431. OPM connector431is detachably coupled to OPM controller441. Typically, more OPM sensors, cables, and connectors are coupled to the OPM controller but they are omitted for clarity. OPM cable421has a ground shield that is coupled to the ground in OPM sensor411and to the ground in OPM connector431. The ground in OPM connector431is coupled to the ground in the controller card in OPM controller441which is grounded through OPM controller441.

OPM sensor411comprises probe laser412and pump laser415, although the two lasers may be combined, or additional lasers might be used. OPM sensor411comprises one or more of coils413, vapor cells414, photodetectors416, and heaters417. OPM sensor411may include signal processors and other electronics but they are omitted in this example. OPM controller441comprises controller Field Programmable Gate Array (FPGA)442, processing card443, and metallic interface444. OPM connector431comprises metallic interface434. Metallic interface434in the OPM connector431is compatible with metallic interface444of controller card443in OPM controller441. For example, metallic interface434may comprise a male metallic interface and metallic interface444may comprise a compatible female metallic interface. Metallic interfaces434and444comprise pins and sockets or some other metallic coupling. Metallic interfaces434and444may have housings, where one housing has a protrusion and the other housing has a corresponding notch to align the interfaces during the coupling process.

OPM connector431has one or more of relays432. One of the relays of relays432in OPM connector431is configured in a normally closed state that shorts the wires that are connected through OPM cable421to probe laser412. Another relay of relays432may normally short the wires to pump laser415. Other relays of relays432may normally short wiring to other sensor components like coils413, photodetectors416, and heaters417. Controller FPGA442has a control interface to relays432through metallic interfaces434and444. FPGA442signals relays432to open when lasers412and415and other components in OPM sensor411are needed for operation. FPGA442may open relays432individually or as a group. Controller FPGA442may open relays432in response to power-up, OPM connector detection, operational sequence, or some other trigger. Relays432disconnect the shorted wiring in response to FPGA442control signaling. Relays432automatically close and re-short the wiring when OPM connector431is unplugged from OPM controller441because the control signal from FPGA442is lost.

In some examples, OPM cable421has additional OPM connectors (in addition to OPM connector431) between OPM controller441and OPM sensor411. The additional connectors may have relays and/or memories that are configured and operate as described above. The additional OPM connectors may couple to each other or to a common interface in a similar manner to OPM connector431and OPM controller card443. The additional connectors may couple to a common interface in the wall of a magnetically-shielded room that contains target401, OPM sensor411, OPM cable421, and OPM connector431. Thus, the memory and/or the relay could be located in the cable, a fob in the cable, or the sensor in some examples.

OPM connector431has at least one of memory433. Memory433comprises storage systems like flash circuitry. Controller FPGA442writes and reads OPM operational data to and from memory433when OPM connector431is coupled to controller card443. The OPM operational data includes an ID, configuration parameters, and performance characteristics of OPM sensor411. For example, memory433may store OPM sensor operating points for OPM sensor411that were determined during OPM sensor diagnostics and testing. The OPM operational data could be servo Proportional-Integral-Derivative (PID) values for lasers412and415. The OPM operational data could be laser resonant currents, heater power values, laser modulation frequencies, cell resonant frequency, and the like. The OPM operational data could indicate component usage time, customer data, help information, or some other OPM information. The OPM operational data could include configuration data like number and type of lasers, heaters, coils, and photodetectors—along with their interconnections and sensor architecture. The OPM operational data could include cell rubidium level, cell pressure, build history and notes. The OPM operational data may comprise laser lock parameters like lock currents, temperatures, and voltages. The OPM operational data may comprise diode drop voltages for resonance at various temperatures.

In operation, OPM connector431couples to OPM controller441. OPM controller441responsively controls relays432to open the shorted wiring to OPM sensor411. OPM controller441reads the memory of OPM connector431to identify OPM operational data for OPM sensor411. OPM controller441inserts the OPM operational data into its processing software. OPM controller441executes the processing software with the OPM operational data to generate control signals for OPM sensor411. For example, OPM controller441may read a diode drop value from OPM connector431and use the diode drop value to control heater417that warms vapor cells414. OPM controller441may read a laser current value from OPM connector431and use the laser current value to control lasers412and415that pump and probe vapor cells414. OPM controller441transfers the control signals to OPM sensor411over OPM connector431and OPM cable421.

OPM sensor411operates in response to the control signals from OPM controller441. Target401emits magnetic waves that form a magnetic field. Vapor cells414are positioned in the target magnetic field. Vapor cells414contain an alkali metal vapor like rubidium. Alternative cells with alkalis, helium, and nitrogen-vacancy centers could be used instead of or along with vapor cells414. Vapor cells414are heated by heaters417and biased by coils413. Pump laser415emits a pump beam that is circularly polarized at a resonant frequency of the vapor in vapor cells414to polarize the atoms. Probe laser412emits a probe beam that is linearly polarized at a non-resident frequency of the vapor in vapor cells414to probe the atoms. The probe beam enters vapor cells414where quantum interactions with the atoms in the presence of the target magnetic field alter the energy/frequency of probe beam by amounts that correlate to the target magnetic field.

Photodetectors416detect the probe beam after these alterations by the vapor atoms responsive to the target magnetic field. Photodetectors416generate and transfer corresponding analog electronic signals that characterize the target magnetic field. In some examples, signal processors may filter, amplify, digitize, or perform other tasks on the analog electronic signals. Photodetectors416or the signal processors transfer an electronic signal that carries the data over OPM cable421to OPM connector431. OPM connector431transfers the electronic signal that characterizes the target magnetic field over to OPM controller441. OPM controller441processes the electronic signal to generate and transfer data that more fully characterizes the target magnetic field. OPM controller441typically processes OPM data from multiple OPMs to model the target magnetic field in three dimensions. OPM controller441transfers the OPM output data to downstream systems.

OPM controller441writes OPM operational data to memory433in OPM connector431. For example, OPM controller441may update OPM operational data like component usage time for the lasers, heaters, coils, cell, photodetector, and the like. OPM connector431stores the OPM data updates in memory433. OPM connector431detaches from OPM controller441. In response, relays432automatically short the wiring when detached from OPM controller441.

In some examples, relays432may detect the coupling of OPM connector431to OPM controller441and open the normal short between the wiring without the control signal from OPM controller441. In other examples, relays432could be replaced by switches, transistors, or another type of device that couples and uncoupled the wiring in response to OPM controller attachment and/or OPM sensor operation in a similar manner to relays432. In some examples, relays432and memory433may be integrated into OPM sensors411. In this configuration, relays432and memory433operate in a manner similar to the operation of memory433and relays432as described above.

FIG.5illustrates OPM sensor411, OPM cable421, OPM connector431, and OPM controller441in OPM MEG system400. OPM sensor411is coupled to OPM connector431by OPM cable421. OPM connector431is coupled to OPM controller441. FPGA442in OPM controller441reads and writes OPM operational data from and to memory433in OPM connector431when OPM connector431is plugged into the OPM controller441.

FPGA442in OPM controller441is coupled to lasers412and415, coils413, photodetectors416, and heater417in OPM sensor411by wire pairs that traverse OPM connector431and OPM cable421. Typically, OPM sensor411is coupled to OPM controller441over seven pairs of wires that travers OPM cable421, however, other connection arrangements are possible. For example, some components of OPM sensor411may share a wire to communicate with OPM controller441. Relay432in the OPM connector431normally shorts the wire pair to lasers412and415. Relay432is controlled by FPGA442in OPM controller441. FPGA442in OPM controller441drives relay432to open the short when lasers412and415are operational. Relay432in OPM connector431automatically shorts the wire pair when the drive signal from FPGA442is not present—like when OPM connector431is unplugged from OPM controller441. In some examples, FPGA442could be replaced and/or augmented by a Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC), or some other type of microprocessor.

In some examples, OPM connector431could be adapted for use with other atomic sensors like atomic clocks. For example, an atomic clock sensor may be coupled to an atomic clock controller by an atomic clock cable with a connector. The atomic clock cable connector could include a relay and/or memory that are configured and operate like the relay and/or memory in OPM connector431. The atomic clock controller could control the relay and/or read/write to the memory like OPM controller431. In some examples, relay432and memory433may instead be located in OPM sensor411. In this configuration, relay432and memory433operate in a manner similar to the operation described above.

FIGS.6-8illustrate OPM connector431and OPM cable421in OPM MEG system400.FIG.6illustrates a top view of OPM connector431.FIG.7illustrates a side view of OPM connector431.FIG.8illustrates a back view OPM connector431. OPM connector431comprises a casing to house relays432and memory433. The casing may be plastic or some other type of suitable material. The size and shape of the casing is not limited. For example, the casing may comprise a width of 32 millimeters, a depth of 33 millimeters, and a height of 12 millimeters. Metallic interface434extends from a front portion of the casing of OPM connector431and is configured to detachably couple to metallic interface444of OPM controller441. OPM cable421is coupled to a rear portion of the casing of OPM connector431. OPM cable421connects OPM connecter431with OPM sensor411. The specific size and shape of OPM cable421is not limited. For example, OPM cable421may comprise a flat ribbon cable with a width of 8.5 millimeters and a length of 20 feet.

FIGS.9-11illustrate OPM sensor411and OPM cable421in OPM MEG system400.FIG.9illustrates a side view of OPM sensor411.FIG.10illustrates a top view of OPM sensor411.FIG.11illustrates a back view of OPM sensor411. OPM sensor comprises a casing to house probe laser412, coils413, vapor cells414, pump laser415, photo detectors416, and heaters417. The casing may be plastic or some other type of suitable material that does not interfere with the operation of OPM sensor411. The size and shape of the casing is not limited. For example, the casing may comprise a width of 13 millimeters, a depth of 15 millimeters, and a height of 26.5 millimeters. OPM cable421is coupled to a rear portion of the casing of OPM sensor411. OPM cable421connects OPM sensor411to OPM connector431. The specific size and shape of OPM cable421is not limited. For example, OPM cable421may comprise a flat ribbon cable with a width of 8.5 millimeters and length of 20 feet. In some examples, OPM sensor411is placed in the vicinity of target401to measure a magnetetic field emitted by target401. For example, OPM sensor411may be embedded into a helmet worn by target401to measure the magnetic field emitted by target401.