US 12,147,022 B2
Dark-field mid-infrared photothermal microscopy
Ji-Xin Cheng, Newton, MA (US); Celalettin Yurdakul, Brighton, MA (US); Haonan Zong, Allston, MA (US); and M. Selim Ünlü, Newton, MA (US)
Assigned to Trustees of Boston University, Boston, MA (US)
Filed by Trustees of Boston University, Boston, MA (US)
Filed on Jun. 2, 2023, as Appl. No. 18/205,152.
Application 18/205,152 is a continuation of application No. 17/704,896, filed on Mar. 25, 2022, granted, now 11,709,352.
Claims priority of provisional application 63/165,890, filed on Mar. 25, 2021.
Prior Publication US 2023/0408805 A1, Dec. 21, 2023
Int. Cl. G02B 21/16 (2006.01); G02B 21/02 (2006.01); G02B 21/36 (2006.01)
CPC G02B 21/16 (2013.01) [G02B 21/025 (2013.01); G02B 21/361 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A wide-field mid-infrared photothermal microscopy (MIP) system for analyzing a sample on a substrate using dark-field illumination, comprising:
a mid-infrared optical source generating a mid-infrared beam, the mid-infrared beam being directed through the substrate and to the sample from a first side of the sample to heat the sample;
a visible light source generating a light, the light illuminating the sample on the substrate from a second side of the sample, the second side of the sample opposite the first side of the sample, and creating a scattered field and a reflected field along a collection path of the system;
an objective pupil within the collection path relayed to a unit magnification 4f system, the unit magnification 4f system including optics spaced at a shared focal length between the following in succession: an objective pupil, a first lens, an intermediate image plane, a second lens, and a back pupil, wherein the reflected field is refocused at the objective pupil; and
a camera positioned at an end of the collection path to collect the scattered field and generate a dark-field image of the sample,
wherein the MIP system is configured to simultaneously heat the sample with the mid-infrared optical source while imaging the sample with the visible light source.