Linear Glass Scales are high-precision optoelectronic positioning sensors that measure linear displacement by reading fine, microscopic grating lines etched onto a thermally stable glass rule. Positioned directly along moving axes of CNC machine tools and precision stages, these closed-loop feedback components eliminate errors caused by thermal expansion, mechanical pitch error, and drive train backlash. Key hardware features typically include high-purity glass scale substrates with sub-micron grating pitches, optoelectronic scanning slider heads, spring-mounted flexible coupling assemblies, lip-seal protective aluminum extrusion housings, and shielded differential signal cables.