The RGH25F from Renishaw Inc. is an optical linear encoder designed for positioning fiber optic splicing equipment in telecommunications applications. The read head measures 36 x 14.3 x 12.5 mm and weighs 22 g. This compact device achieves resolutions from 5 µm to 10 nm and speeds of up to 300 mm/s for positioning on six-axis precision stages. The company says the noncontact design eliminates hysteresis, friction and wear, and that self-tuning electronics and double-shielded cable ensure reliability, even in noisy environments. The reflective, cut-to-length scale is a gold-plated steel tape, lacquered to protect against dirt. Filtering optics provide immunity to dust, scratches and oils, ensuring signal stability.