The Lida 400 linear encoder series has been redesigned to be mechanically compatible with the previous Lida 400 family. Scanning units are interchangeable with older graduations. Still maintaining a 20-micron graduation, and interpolation available up to 100 times from the scanning unit, the exposed encoder system can have a resolution of 50 nm and accuracies to ±1 micron. A new multi-colored status LED on the side of the scanning unit indicates the signal levels during installation. The LED can be used as a quick status check of the encoder to determine functionality. It also indicates the reference mark signal quality.