US 11,774,785 B2
Optical limiter and method for limiting radiant flux
Marco Menchetti, London (GB)
Assigned to BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY, London (GB)
Appl. No. 17/995,165
Filed by BRITISH TELECOMMUNICATIONS PUBLIC LIMITED COMPANY, London (GB)
PCT Filed Mar. 10, 2021, PCT No. PCT/EP2021/056074
§ 371(c)(1), (2) Date Sep. 30, 2022,
PCT Pub. No. WO2021/197780, PCT Pub. Date Oct. 7, 2021.
Claims priority of application No. 20166647 (EP), filed on Mar. 30, 2020; and application No. 2004584 (GB), filed on Mar. 30, 2020.
Prior Publication US 2023/0140182 A1, May 4, 2023
Int. Cl. G02F 1/01 (2006.01); G02B 6/35 (2006.01); G02B 26/02 (2006.01)
CPC G02F 1/0126 (2013.01) [G02B 6/3512 (2013.01); G02B 26/023 (2013.01); G02F 1/0147 (2013.01)] 15 Claims
OG exemplary drawing
 
1. An optical limiter for limiting radiant flux of an optical source beam, the optical limiter comprising:
an optical control port for illumination by an optical control beam originating from the optical source beam, an optical input port for illumination by an optical transmission beam originating from the optical source beam, and an optical output port for illumination by the optical transmission beam, wherein the optical control port can be the optical input port, the optical input port can be the optical control port, and the optical control port, the optical input port, and the optical output port can be distinct, and wherein the optical source beam can serve as both the optical transmission beam and the optical control beam; and
a thermally driven light mill,
wherein the thermally driven light mill is arranged with respect to the optical input port, the optical control port, and the optical output port, such that:
illumination of the optical control port by the optical control beam drives the thermally driven light mill to rotate only when the optical control beam has a radiant flux equal to or in excess of a predetermined radiant flux threshold; and
rotation of the thermally driven light mill causes an area of the optical output port illuminated by the optical transmission beam to change.