激光测高仪是测量激光脉冲的飞行时间来获得测高仪与探测目标之间的距离，因此激光飞行时间测量的准确性是衡量其系统能力的根本指标。文中阐述了时间间隔高精度测量技术及其最新进展。介绍了传统的测量时间间隔的方法的不足，引入了插入法。并采用粗测和精测相结合的方法来满足大范围、高精度的测量需求。文中详细介绍了模拟插入法、Vernier法、延时线法以及时间数字转换法在FPGA新技术中的应用。

A pulsed time-of-flight laser altimeter operates by transmitting a short laser pulse to an optical visible target and by detecting the reflected pulse by an optical detector. The measured distance is calculated from this flight time. So the accuracy of laser time interval is a basic beacon to measure its system. The technology of distance measurement is discussed. The shortage of traditional measurements is introduced. Using coarse and fine measurements together to meet the requirement of large range and high resolution. The following methods are described: analogue interpolation method,the Vernier method,tapped delay lines. Special attention has been paid to converters utilizing integrated delay lines for digital conversion of TIs,include using designs with phase-locked loop and delay-locked loop circuits in FPGA.