US 12,443,140 B1
Phase compensation method for digital holography systems
Philip Gatt, Berthoud, CO (US); Christopher Michael Ryan, Erie, CO (US); Brian Krause, Erie, CO (US); and Samuel Trent Thurman, Arvada, CO (US)
Assigned to Lockheed Martin Corporation, Bethesda, MD (US)
Filed by LOCKHEED MARTIN CORPORATION, Bethesda, MD (US)
Filed on Aug. 26, 2021, as Appl. No. 17/458,024.
Int. Cl. G03H 1/04 (2006.01); G01B 9/02 (2022.01); G01B 9/02015 (2022.01); G03H 1/08 (2006.01); G06V 10/88 (2022.01)
CPC G03H 1/0443 (2013.01) [G01B 9/02032 (2013.01); G01B 9/02047 (2013.01); G03H 1/0866 (2013.01); G06V 10/895 (2022.01); G03H 2001/0445 (2013.01); G03H 2001/0469 (2013.01); G03H 2225/33 (2013.01)] 9 Claims
OG exemplary drawing
 
1. 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.