Servo Motor Encoder Disk

Servo systems operating across wide temperature ranges face feedback instability due to thermal expansion mismatch between the encoder disk and the motor shaft. Changes in ambient or operational temperature result in minor but accumulative geometric shifts, leading to positional offset over time. Encoder disks are constructed using low-expansion optical substrates such as fused quartz or dimensionally stabilized polyimide-laminated films with thermal expansion coefficients under 0.5 ppm/°C.  

Photodetector arrays and optical readheads require precise track-to-sensor alignment to maintain decoding accuracy. Variations in disk hub machining or concentricity introduce alignment shifts between the index pulse and the sensor array, affecting homing precision and encoder calibration. Encoder disks are manufactured with concentricity tolerances better than 2 µm and include fiducial patterns aligned to the index mark for automated visual registration.