An exposed incremental linear encoder from Heidenhain Corp., Schaumburg, Ill., combines a photolithographically produced grating on its scale tape with newly designed scanning optics to guarantee high accuracy. The scanning head on the LIDA 400 has overall height of only 12 mm (0.47 in.) and can mount in tight spaces. Beam path and photodetector configuration is such that the scanning surface is a relatively large 14.5 mm2 despite the small scanning head, making the encoder relatively tolerant to contamination.

Grating period is 20 microns. Available interfaces are the widely used 1 VPP and TTL formats. LIDA 400s can be specced to measure lengths up to 30 m and hit traversing speeds of up to 480 m/min (18,900 ipm). The encoders are available with reference marks and now also feature integrated, magnetic limit switches.