This module includes both an infrared emitter as well as receiver. When the infrared light bounces off an object the comparator examines if the reflected light meets a threshold and emits a digital signal if it does. The threshold is adjustable via the onboard potentiometer. The working distance of this sensor is 2-30CM.
Robot obstacle avoidance, assembly line counting, and black and white line tracking are a few use cases for this module.
Since light reflects differently off of objects of different colors and shapes the effective range objects are detected at may differ based on these factors.
10 x Infrared Reflection Sensor