Optical technology provides maximum resolution and accuracy by scanning the position of a coded material typically using infrared light. Optical Single-Turn Technology Optical encoders are made up of a revolving shaft with a codedisc, an infrared light source and an optoelectronic scanning unit. The codedisc is made of glass or unbreakable plastics and typically coded in tracks using a so called Gray-code. Infrared light from an LED is collimated and passes through the code disc. On the opposite site a photoreceptor array with reticle picks up the information from the tracks. At every angle position a unique sequence of photoreceptors are blocked from light by dark segments on the code disc. Optical Multi-Turn Technology Optical multi-turn sensing within an encoder is done using a mechanical gearing which basically connects several single-turn stages. Reliable and wear free plastic gearings use coded gearwheels (codewheels) to minimize costs and space.