Ultra-compact encoder using Talbot interference

A newly developed encoder using a vertical cavity surface-emitting laser (VCSEL) is presented. This high-resolution encoder is the smallest in its class and has a large allowance for the gap alignment between the sensor head and the scale. These features are realized simultaneously by adopting VCSEL and multi-functional IC and by incorporating the technique of Talbot interference: no optical elements are required for the sensor head except a light source and a photosensor, which can be reduced in size by the semiconductor production technology. In comparison to our previous model, this encoder has greater tolerance against optical disturbances to the scale such as dust.