US 12,276,782 B2
Optical microscopy
Tuomas Pertti Jonathan Knowles, Cambridge (GB); Pavan Kumar Challa, Cambridge (GB); Kadi Liis Saar, Cambridge (GB); Quentin Alexis Peter, Cambridge (GB); and Zenon Toprakcioglu, Cambridge (GB)
Assigned to Cambridge Enterprise Limited, Cambridge (GB)
Appl. No. 17/296,212
Filed by Cambridge Enterprise Limited, Cambridge (GB)
PCT Filed Nov. 22, 2019, PCT No. PCT/GB2019/053304
§ 371(c)(1), (2) Date May 21, 2021,
PCT Pub. No. WO2020/104813, PCT Pub. Date May 28, 2020.
Claims priority of application No. 1819029 (GB), filed on Nov. 22, 2018; and application No. 1913536 (GB), filed on Sep. 19, 2019.
Prior Publication US 2022/0011560 A1, Jan. 13, 2022
Int. Cl. G02B 21/00 (2006.01); G01N 21/45 (2006.01); G01N 21/47 (2006.01); G02B 21/14 (2006.01); G02B 21/36 (2006.01)
CPC G02B 21/0056 (2013.01) [G01N 21/45 (2013.01); G01N 21/4795 (2013.01); G02B 21/14 (2013.01); G02B 21/361 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method of increasing the signal contrast in interferometric scattering optical microscopy, the method comprising:
providing a particle detection region having a boundary defined by an interface;
illuminating a particle in the particle detection region with coherent light using an objective lens such that the light is reflected from the interface and scattered by the particle;
capturing the reflected light and the scattered light using the objective lens;
selectively attenuating the captured reflected light using a spatial filter; and
providing the selectively attenuated captured reflected light and the captured scattered light to an imaging device to image interference between the reflected light and the scattered light;
wherein the objective lens has an optical axis, the method further comprising
providing the coherent light to the objective lens offset from the optical axis of the objective lens such that the coherent light illuminating the particle is at an oblique angle to the interface,
wherein the spatial filter is an off-axis spatial filter at or adjacent a Fourier plane of the objective lens, and is configured to selectively mask a region of the Fourier plane offset from the optical axis in an opposite direction to the offset from the optical axis of the optical path of the coherent light to the objective lens.