TECHNICAL FIELD

The present invention relates generally to sensor systems, and specifically to a vector-sensitive electrometer.

BACKGROUND

Electric field measurement via electrometers has many useful applications. Detectable electric fields can include DC electric fields, as well as AC electric fields (e.g., radio frequency (RF) fields which can correspond to communications signals). The detection of electric fields can be implemented for anti-spoofing and and/or anti-jamming capability in electronic warfare environments. For example, if a jamming or spoofing signal can be detected, then the jamming signal or spoofing signal can be filtered or demodulated out to provide for a baseband signal of interest without undesired or adversarial interference. As an example, multiple antennas arranged in an array can provide for directional detection of a signal, such as to provide a detectable directional of a source of the signal.

SUMMARY

One example includes an electrometer system that includes a sensor cell and a probe laser to generate a probe beam directed through the sensor cell in a first direction and exiting the sensor cell as a detection beam. The system also includes a coupling laser to generate a coupling beam directed through the sensor cell collinearly and anti-parallel with the probe beam. The system also includes a reference signal generator configured to generate a reference signal having a predetermined polarization and a predetermined frequency through the sensor cell. The system further includes a detection system configured to monitor the detection beam to determine signal characteristics of an external signal based on an intensity of the detection beam and based on the predetermined polarization and the predetermined frequency of the reference signal.

Another example includes a method for detecting an external signal via an electrometer system. The method includes directing a probe beam through a sensor cell comprising an alkali metal vapor in a first direction, directing a coupling beam through the sensor cell collinearly and anti-parallel with the probe beam, and directing a reference signal having a predetermined polarization and a predetermined frequency through the sensor cell. The method also includes monitoring a detection beam corresponding to the probe beam exiting the sensor cell to ascertain a beat frequency that is associated with a difference between the predetermined frequency and the frequency of the external signal. The method further includes determining at least one of a frequency, an amplitude, and a polarization of the external signal based on the beat frequency.

Another example includes electrometer system that includes a sensor cell and a probe laser to generate a probe beam directed through the sensor cell in a first direction and exiting the sensor cell as a detection beam. The system also includes a coupling laser to generate a coupling beam directed through the sensor cell collinearly and anti-parallel with the probe beam. The system also includes optics configured to provide the probe beam and the coupling beam to be collinear and anti-parallel with respect to each other and to focus each of the probe beam and the coupling beam to a measurement point within the sensor cell. The system also includes a reference signal generator configured to generate a reference signal having a predetermined polarization and a predetermined frequency through the sensor cell. The system further includes a detection system configured to monitor the detection beam to determine signal characteristics of an external signal at the measurement point based on an intensity of the detection beam and based on the predetermined polarization and the predetermined frequency of the reference signal.

