US 11,885,742 B2
Receiver, detection system, and detection method
Yuma Matsuda, Tokyo (JP); and Akihiro Tanaka, Tokyo (JP)
Assigned to NEC CORPORATION, Tokyo (JP)
Appl. No. 17/440,382
Filed by NEC Corporation, Tokyo (JP)
PCT Filed Jan. 27, 2020, PCT No. PCT/JP2020/002766
§ 371(c)(1), (2) Date Sep. 17, 2021,
PCT Pub. No. WO2020/195102, PCT Pub. Date Oct. 1, 2020.
Claims priority of application No. 2019-058455 (JP), filed on Mar. 26, 2019.
Prior Publication US 2022/0155224 A1, May 19, 2022
Int. Cl. G01N 21/59 (2006.01); G01J 3/42 (2006.01); G01N 21/53 (2006.01); G01N 33/00 (2006.01); G08B 17/10 (2006.01)
CPC G01N 21/59 (2013.01) [G01J 3/42 (2013.01); G01N 21/534 (2013.01); G01N 33/0027 (2013.01); G08B 17/10 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A receiver comprising:
a divider configured to divide an optical signal transmitted for detecting a detection target on a traveling path over a plurality of paths including a first path and a second path;
a detector configured to detect a received light intensity of the optical signal at a first position of the first path where the received light intensity increases when an optical axis of the optical signal is shifted and at a second position of the second path where the received light intensity decreases when the optical axis is shifted;
a processor; and
a memory storing instructions executable by the processor to:
calculate a received light intensity ratio between the received light intensity at the first position as has been detected and the received light intensity at the second position as has been detected; and
determine presence or absence of an optical axis shift based on a change in the received light intensity ratio over time.