Patent ID: 11885742
Assignee: NEC CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
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.