Scanning, optical

Position, angle and speed monitoring for rotary or linear encoders using LEDs, code patterns and photodiodes. The tick marks (on incremental encoders) or codes (on absolute encoders) are inscribed as digital patterns on a glass, metal or plastic disc and are scanned using a light source (light emitting diode) and photo-diodes. Encoders with optical scanning typically have higher resolutions than encoders that use magnetic scanning.