Subdivision is one of the essential methods to improve the measurement resolution of optical instruments. A new method is proposed to solve lambda/16 bidirectional subdivision and direction recognition for orthogonal interference signals by constructing two sets of reference signals and using zero-cross detection. The experimental results prove that the method is efficient for orthogonal signals and has good real-time performance by field-programmable gate array realization. This method is easy to realize by use of electronic design automation tools and can be widely used in the signal processing system of optical measurement instruments such as a moiré fringe measurement system and laser interferometer.