Optical sensor

An optical sensor comprising:

• a monitor-light-emitting device that emits light at a first timing;
• a detection-light-emitting device that emits light at a second timing different from the first timing;
• a light receiving device arranged adjacent to the monitor-light-emitting device and the detection-light-emitting device;
• and
• a light-guiding member disposed in front of the detection-light-emitting device and the light receiving device;
• wherein reference light corresponding to the light emitted from the detection-light-emitting device propagates through the light-guiding member and is received by the light receiving device;
• wherein light emitted from the detection-light-emitting device is transmitted through the light-guiding member, and is reflected by a target object located in front of the optical sensor, and is guided back by the light-guiding member to the light receiving device;
• wherein a visor portion is disposed between the monitor-light-emitting device and the light-guiding member, such that light emitted from the monitor-light-emitting device is directly incident on the light receiving device;
• and
• wherein presence or absence of target object is determined based on a measured amount of light received by the light receiving device when the detection-light-emitting device emits light and a measured amount of light received by the light receiving device when the monitor-light-emitting device emits light.