http://www.usa.canon.com/cusa/semiconductor/products/encoder_optolectronic_components/laser_rotary_encoder/k_1?pageKeyCode=writeReviewPage
K-1
3333342
Overview
Canon K-1 series Laser Rotary Encoders offer high performance (high resolution, accuracy, & precision) in a very compact 36mm diameter body. All models utilize semiconductor laser diode, high precision grating disk, and diffraction & intereference position sensing methodology.