图像采集时易受背景光的干扰，影响成像质量。激光锁定成像技术利用正弦调制的辅助激光实现了良好的背景光消除，但成本高和安全性不足，且要求图像传感器帧频足够高以满足调制速度。因此对该技术进行扩展，从理论上探讨除正弦波外的其他信号调制辅助光源的可行性和背景光消除机制。采用LED为辅助光源，并利用优化图像采集的控制方式降低对图像传感器帧频的要求。理论研究表明，锁定成像技术辅助光源的调制信号可扩展到一个周期内积分为零的任何波形信号。采用正弦波、方波、三角波、锯齿波调制LED光源的实验结果表明，在一个调制周期内，所提技术采用4种调制波形后在不同采样率下都取得较好的背景光消除效果，且该技术对辅助光源及图像传感器帧频的要求不高，验证了理论的可行性。

Background light affects an image and degrades its quality. Laser lock-in imaging is an outstanding technology for reducing the impacts of the background light by a sine auxiliary modulation. However, the technology is expensive and not safe enough, and it requires that the frame rate of the image sensor is high enough to meet the modulation speed. In this study, the technology is extended theoretically to investigate the feasibility of a non-sine auxiliary-modulated light and mechanism of the background light elimination. We used an LED as the auxiliary light and the control mode of optimizing image acquisition to reduce the requirement for the frame rate of the image sensor. According to our findings, the modulation signal of the auxiliary light of the locked imaging technology can be extended to any waveform signal with zero integration in a period. Experiments using sine, square, triangular, and sawtooth signals to modulate an LED light show that in a modulation cycle the proposed technology uses four modulation waveforms to achieve a good background light elimination effect at different sampling rates. The proposed technology has low requirements for auxiliary light sources and frame rates of image sensors, providing theoretical feasibility.