US 12,298,717 B2
Methods of recording and reproducing holograms
Michal Makowski, Warsaw (PL); Maciej Sypek, Warsaw (PL); Jaroslaw Bomba, Jozefow (PL); and Andrzej Stupakiewicz, Bialystok (PL)
Assigned to Politechnika Warszawska, Warsaw (PL); and Uniwersytet w Bialymstoku, Bialystok (PL)
Filed by Politechnika Warszawska, Warsaw (PL); and Uniwersytet w Bialymstoku, Bialystok (PL)
Filed on Oct. 26, 2022, as Appl. No. 17/973,972.
Claims priority of application No. 439338 (PL), filed on Oct. 27, 2021.
Prior Publication US 2023/0131927 A1, Apr. 27, 2023
Int. Cl. G03H 1/10 (2006.01); G03H 1/22 (2006.01)
CPC G03H 1/10 (2013.01) [G03H 1/2205 (2013.01); G03H 2001/221 (2013.01); G03H 2223/24 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A method comprising:
a) recording a hologram in a thresholded opto-magnetic medium, including
a(i) producing a collimated recording beam with a pulsed laser,
a(ii) selectively modulating intensity of the recording beam by passage through a modulator to produce a modulated recording beam,
a(iii) spatially shaping the modulated recording beam by passage through a shaping element to produce a shaped modulated recording beam,
a(iv) causing the shaped modulated recording beam to be convergent by passage through an aspheric lens to produce a convergent shaped modulated recording beam,
a(v) deflecting bidirectionally with a Micro Electro-Mechanical Systems (MEMS) mirror that is in operative connection with the modulator, the convergent shaped modulated recording beam, wherein multiple disposed locations on a surface of the opto-magnetic medium are exposed to a constriction of the convergent shaped modulated recording beam,
wherein the constriction of the convergent shaped modulated recording beam at the surface
has an asymmetrical cross section, and
causes a change in magnetization of magnetic domains of the medium where energy of the constriction exceeds a threshold of magnetization reaction of the magnetic domains,
b) subsequent to recording the hologram, reconstructing the hologram including:
b(i) illuminating the changed opto-magnetic medium of (a)(v) with a collimated laser beam,
b(ii) focusing with a lens, light from the illuminated opto-magnetic medium onto a detection matrix.