Description: TCRT5000 Reflective IR Optical Sensor with Transistor Output
Specifications: The TCRT5000 is a two part IR proximity sensing module. One side emits IR light, and the other side receives the reflected light. Works best at close range. See the schematic below for how to wire one up.
Here is a link out to the Vishay spec sheet
If you don't already have some 100 ohm and 4.7k resistors, you can pick a few up for this and your future projects here: