An innovative, noncontact, dynamic method is proposed for linear velocity measurement based on phototransistor array. According to the method, an optoelectronic measurement system has been established with three parts: a stable linear laser, fixed on the moving target, is applied as the optical signal emitting unit; a phototransistor array with complex programmable logic devices, positioned parallel to the moving direction and face to face with the laser, is designed as optical signal detecting unit; high-speed data picking cards and a signal processing software are used as the signal acquisition and processing unit. The single cycle frequency measurement theory and the piecewise polynomial fitting are applied in the instrumentation. The effectiveness and reliability of the measurement was demonstrated through three example linear movements.
"Noncontact dynamic measurement of linear velocity using phototransistor array," Optical Engineering 51(4), 043606 (20 April 2012). https://doi.org/10.1117/1.OE.51.4.043606