Advanced bidirectional subdivision algorithm for orthogonal fringes in precision optical measurement instruments

Subdivision is one of the essential methods to improve the measurement resolution of optical instruments. A novel method is studied to solve the λ/2n+2 bidirectional counting of orthogonal interference signals by constructing n sets of reference signals and using the zero-cross detection. The advantage of this method is that the effective bidirectional fringe counting can be achieved easily by the computer programming. This method can be used widely in the signal processing system of the optical measurement instruments, such as the Moiré fringe measurement instruments and the laser interferometers.