The QTR-1RC reflectance sensor carries a single infrared LED and phototransistor pair in an inexpensive, tiny 0.5" x 0.3" module that can be mounted almost anywhere and is great for edge detection and line following. The output is designed to be measured by a digital I/O line. This sensor is sold in packs of two units.
Documentation and other information
Pololu QTR Reflectance Sensor Application Note (Printable PDF: QTR_application_note.pdf)
Information about using the Pololu QTR-xA and QTR-xRC reflectance sensors, including sample oscilloscope screen captures of sensor outputs.
Pololu AVR C/C++ Library User’s Guide (Printable PDF: pololu_avr_library.pdf)
Information about installing and using the C/C++ libraries provided for use with Pololu products.
Arduino Library for the Pololu QTR Reflectance Sensors (Printable PDF: QTR_arduino_library.pdf)
Pololu AVR Library Command Reference (Printable PDF: avr_library_commands.pdf)
A reference to commands provided in the Pololu C/C++ and Arduino libraries for the AVR.