US 11,867,620 B2
Ultrafast chemical imaging by widefield photothermal sensing of infrared absorption
Ji-Xin Cheng, Newton, MA (US); Yeran Bai, Allston, MA (US); Delong Zhang, Brighton, MA (US); Ali Shakouri, West Lafayette, IN (US); and D. Kerry Maize, West Lafayette, IN (US)
Assigned to Purdue Research Foundation, West Lafayette, IN (US)
Appl. No. 17/600,438
Filed by Purdue Research Foundation, West Lafayette, IN (US)
PCT Filed Dec. 10, 2019, PCT No. PCT/US2019/065466
§ 371(c)(1), (2) Date Sep. 30, 2021,
PCT Pub. No. WO2020/123497, PCT Pub. Date Jun. 18, 2020.
Claims priority of provisional application 62/777,421, filed on Dec. 10, 2018.
Prior Publication US 2022/0381684 A1, Dec. 1, 2022
Int. Cl. G01N 21/3577 (2014.01)
CPC G01N 21/3577 (2013.01) [G01N 2201/06113 (2013.01)] 44 Claims
OG exemplary drawing
 
1. A system for widefield imaging of infrared absorption properties of a sample using a photothermal effect, the system comprising:
an infrared pump source configured to generate an infrared pump beam;
a probe source configured to generate a probe beam;
at least one pulse generator configured to initiate a series of synchronized pulses of the infrared pump beam and the probe beam;
an image sensor configured to collect:
a hot frame comprising a spatially-resolved image of probe light collected from the sample with the infrared pump beam intersecting the probe beam at the sample; and
a cold frame comprising a spatially-resolved image of probe light collected from the sample with a reduced intensity of the infrared pump beam intersecting the probe beam at the sample; and
a processor configured to measure a change between the hot frame and the cold frame to simultaneously generate a plurality of signals indicative of a level of infrared absorption at each of a corresponding plurality of spatially-resolved points on the sample.