Two-Dimensional Lock-in Amplifier Algorithm in Spatial Domain

Abstract

An algorithm based on a two-dimensional lock-in amplifier method has been proposed for extracting complex plane components in images. Traditional one-dimensional time-frequency lock-in amplifier estimates the amplitude and phase of a periodic signal at a frequency determined by a reference signal that may be submerged by noise. In the field of digital image processing, it is necessary to analyze the information in the spatial domain. In this paper, a mathematical model has been established to describe the complex plane component in the image, and a two-dimensional lock-in amplifier algorithm has been developed. Compared with traditional lock-in amplifier algorithms, the proposed algorithm can be used to process signals with higher dimensions. Simulation and experimental results show that the proposed algorithm can effectively extract the complex plane components polluted by noise at given frequencies. This two-dimensional lock-in amplifier algorithm can be applied to the extraction and reconstruction of fringe patterns in images submerged by noise. The limitation of the proposed algorithm has been discussed.

Phase sensitive detection for embedded sensors

“…Compared to the analog method, DLIA presents several advantages, such as reduced circuit dimensions, lower cost and, mainly, the convenience of adjusting and changing parameters via software [13][14][15][16]. One can observe active ongoing research to improve measurement performance [17][18][19][20][21][22]. The interest in implementing DLIA integrated with sensors or portable instruments [23,24] has been expanding alongside the demand for low-cost microcontrollers and microprocessor-based implementations [17,25].…”