针对传统的二次混频式激光测距仪鉴相精度不高，难于消除系统误差等问题，提出了正交混频相位激光测距法，利用成熟的正交调制技术进行激光光强的幅度调制，提高了基于二次混频原理的激光测距仪的鉴相精度，并且通过改变低频信号相位来获得两个相对很小的频差，易于消除系统附加相移，大大简化了二次混频式激光测距仪的硬件设计。详细阐述了基于正交混频相位测距方法的激光测距原型机设计要点。系统原型机设计方案采用了集成度很高的正交调制芯片完成，结构紧凑没有冗余元件。原型机实验精度达到±1.52 mm，在62.5 MHz频点下测相精度达到0.042°，并且可以很方便地通过加入多频调制的方法大大提高测量距离，是采用二次混频法进行相位激光测距的优秀解决方案。

Traditional laser range finder based on two-step frequency mixing has a poor phase measuring accuracy and it is difficult to eliminate systematic errors. A novel quadrature modulation method to achieve amplitude modulation of laser intensity is proposed. This method improves the accuracy of phase measuring and greatly simplifies the hardware design of laser range finder based on two-step frequency mixing. Design features of the prototype have been expounded in detail. A highly integrated quadrature modulator chip is used in prototype design, making the whole system compact and with no redundant components. The measured accuracy approaches ±1.52 mm when the modulation frequency is 62.5 MHz and the dynamic range can be improved by multimodulated frequency method as revealed by a detailed analysis.