US 11,747,204 B2
High sensitivity frequency-domain spectroscopy system
Scott M. Hendrickson, Baltimore, MD (US); Jeremiah J. Wathen, Annapolis, MD (US); Michael J. Fitch, Catonsville, MD (US); David W. Blodgett, Ellicott City, MD (US); and Vincent R. Pagan, Ellicott City, MD (US)
Assigned to The Johns Hopkins University, Baltimore, MD (US)
Filed by The Johns Hopkins University, Baltimore, MD (US)
Filed on Aug. 4, 2021, as Appl. No. 17/394,143.
Claims priority of provisional application 63/062,454, filed on Aug. 7, 2020.
Prior Publication US 2022/0042849 A1, Feb. 10, 2022
Int. Cl. G01J 3/433 (2006.01); G02B 3/04 (2006.01); G01J 3/02 (2006.01); G01J 3/28 (2006.01)
CPC G01J 3/4338 (2013.01) [G01J 3/0208 (2013.01); G01J 3/0264 (2013.01); G01J 3/2823 (2013.01); G02B 3/04 (2013.01); G01J 2003/4332 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A system comprising:
first and second radiation sources configured to generate respective first and second beams of radiation to irradiate a target along respective first and second paths, each of the first and second beams comprising:
a first wavelength at a first modulation frequency; and
a second wavelength at a second modulation frequency;
first and second detectors each comprising:
a photo-sensitive element configured to receive scattered radiation resulting from the first and second beams and to generate first or second detection signals respective to the first or second detectors based on the received scattered radiation;
a Faraday shielding enclosure;
a signal amplifier configured to amplify the first or second detection signals; and
a frequency mixer configured to frequency-adjust the first or second detection signals;
a signal digitizer configured to receive the first and second detection signals after the frequency-adjusting to generate a digitized signal;
a controller configured to provide timing information to the first and second radiation sources to inform an activation scheme of the first and second radiation sources and corresponding radiation detection events at the first and second detectors; and
an analyzer configured to analyze the digitized signal and the timing information to determine at least amplitude and phase information of the scattered radiation.