Phase compensation method for digital holography systems
AssigneeLockheed Martin Corporation
InventorsPhilip Gatt, Christopher Michael Ryan, Brian Krause, Samuel Trent Thurman
Life of this patent
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Abstract
Systems and methods are provided for a digital holography system. The subject system uses wide-bandwidth data, monitor beams, and signal beams to form a digital interference, yielding a reference phase and angle that can be used to compensate DH phase errors. DH systems disclosed herein can provide an ability to sense and correct for phase errors and/or instabilities to perform DH vibrometry. Such a system provides a compact and low-cost solution to improve sensing in, for example, systems that rely on phase stability for precision 3D and/or vibration imaging.
Claims9
A digital holography system comprising:
- a laser source configured to produce:
- a continuous wave master oscillator (MO) reference beam;
- a MO transmit (TX) beam;
- a MO local (LO) beam;
- a TX beam for transmission to a target;
- a TX monitor beam for sampling the TX beam;
- and
- a digital holography (DH) LO laser beam for interfering with a TX return signal beam from the target;
- an optical processing subsystem configured to apply a frequency shift and a time delay to the MO RX laser beam to produce a DH LO beam;
- a DH receiver for combining a return signal beam from the target with the DH LO beam to produce a complex return signal;
- a wide-bandwidth receiver configured to:
- combine the DH LO beam with a continuous wave (CW) MO reference beam to produce a DH LO electrical signal;
- and
- combine the TX monitor beam with the CW MO reference beam to produce a TX monitor electrical signal;
- a DH compensation subsystem configured to:
- modulate at least one of the DH LO electrical signal or the TX monitor electrical signal based on the frequency shift and the time delay to produce a complex DH LO signal and a complex TX monitor signal;
- and
- producing a compensation phasor based on the complex DH LO signal and the complex TX monitor signal;
- and
- a DH processor configured to apply the compensation phasor to the complex return signal to produce a compensated signal.
Dependencies are inferred from the claim text.