Two-dimensional phase sensitive detector and its application to demodulating amplitude modulated image

Abstract

<sec> Two-dimensional spatial modulation and demodulation technology can improve the weak signal detection capability of photoelectric detection system in a stronger noise background. In this paper, a two-dimensional phase-sensitive detector for the high-precision demodulation of 2D spatial amplitude-modulated signal is proposed. In this paper, we introduce the principle of extracting modulating signals from 2D amplitude modulated images by using 2D phase-sensitive detector, and simulate its ability to suppressing noise and extracting signal from the amplitude-modulated images buried in noise. In order to eliminate the influence of grid image generated by metal wire mesh sandwiched between two layers of glass on the detection of shielding glass defects, the methods of filtering in the frequency domain, rectifying plus filtering and two-dimensional phase sensitive detector are used to demodulate the mesh amplitude-modulated image, and the effects of extracting defects and suppressing noise are compared with each other. </sec><sec> The principle and experimental results of defect detection of ordinary glass by using external carrier are also provided. The simulation results and the detection results show that the two-dimensional phase-sensitive detector can be used to demodulate spatial two-dimensional amplitude-modulated image produced by optical modulators to extract two-dimensional measurement signals. The 2D phase-sensitive detector can greatly improve the signal-to-noise ratio of the output image, increase detection accuracy and the ability to extract modulating signals from the amplitude-modulated image buried in noise. </sec>