CNB13020R Reflective Photosensor from Tinkering Supplies
The CNB13020R is an ultraminiature (2.7 3.4 x 1.5 mm) module consisting of an IR LED and a high sensitivity Si phototransistor. It has a fast (20us) response time and is optomized to detect objects within 1 mm of module. It is ideal for quadrature encoders and other high speed, high precision positioning applications.