Rotational speed measurement using one-dimensional position sensitive detector

Rotational speed is a key parameter of rotating machineries and it is essential for the control of these devices to measure rotational speed in real time. The rotational speed measurement method based on the photo-electric reflective principle has the advantage of being non-contacted, but it is easy affected by background light and its measuring range is limited. In this paper, a novel rotational speed measurement method was proposed based on a one-dimensional position sensitive detector (PSD). Compared with traditional rotational speed measurement methods, the novel design did not need additional devices and nearly unaffected by background light. What's more, experiments show that the measuring range of the prototype is largely broadened (up to 10
⁴
r/min), and the error is less than ±0.2% at both low and high speed.