US 12,276,593 B2
Optical trap using a focused hollow beam of unequal axisymmetry and no angular momentum for trapping and rotating airborne particles
Jessica A. Arnold, Chevy Chase, MD (US); Aimable Kalume, Adelphi, MD (US); Yongle Pan, Ellicott City, MD (US); and Gorden Videen, Silver Spring, MD (US)
Assigned to The United States of America as represented by the Secretary of the Army, Washington, DC (US)
Filed by U.S. Army DEVCOM, Army Research Laboratory, Adelphi, MD (US)
Filed on Mar. 14, 2022, as Appl. No. 17/694,326.
Prior Publication US 2023/0314299 A1, Oct. 5, 2023
Int. Cl. G01N 15/1434 (2024.01); G01N 15/14 (2024.01); G21K 1/00 (2006.01)
CPC G01N 15/1434 (2013.01) [G21K 1/006 (2013.01); G01N 2015/1445 (2013.01); G01N 2015/1493 (2013.01); G01N 2015/1497 (2013.01)] 23 Claims
OG exemplary drawing
 
1. An optical trap for trapping and holding airborne particles comprising:
a light source for generating a beam of light;
a spatial light modulator (SLM) configured to generate a computer-generated hologram (CGH) of an orienting hollow beam having unequal axisymmetry in two orthogonal directions in a plane with a substantially hollow ring geometry cross-section and no angular momentum;
an optical focusing element for focusing the orienting hollow beam to a single focal point;
a trapping region where an airborne particle can be present to be trapped and held at or near the single focal point of the focused optical focusing element; and
an imaging and/or measuring system configured to image and/or measure particles in the trapping region,
wherein the SLM is programmed to rotate the CGH, or the SLM is mounted on a rotating stage, such that the orienting hollow beam can rotate about a fixed axis normal to the beam propagating direction to the trapping region, in order to rotate the trapped airborne particle at or near the single focal point of the focusing the orienting hollow beam.