触发方式对低速相机采集图像时间准确度的影响

针对使用低速相机连续采集高时间精度图像序列的需求，系统地研究了3种典型相机触发模式（硬件触发模式、软件触发模式、连续采集模式）下，低速相机采集图像序列时间精度、误差的大小以及误差规律.基于高精度时间光编码技术，对各种触发模式下采集的单张图像进行时间编码，从而获得了采集每张图像的准确时间，计算不同触发方式下得到的图像采集时间间隔与标准时间间隔之间的误差（走时误差）.实验结果表明:软件触发的图像序列精度较差，走时误差值为32.2 ms，硬件触发与连续采集模式下图像序列的时间精度高，走时误差值均分布在±0.1 ms范围内，稳定性好.对于对时间精度要求较高的实验，在实验过程中应尽量选取精准的触发模式，即硬件触发模式或连续采集模式. 

Influence of Trigger Mode on Acquisition Time of Low-Speed-Camera Image Sequence

In order to enable low-speed cameras to acquire high time precision image sequences, the study mainly investigated the acquisition time accuracy and the error of image sequences of low-speed cameras triggered by three typical modes (hardware trigger mode, software trigger mode and continuous acquisition trigger mode).The acquisition time was obtained by a method based on a light-time coding technique. First, the time message was encoded into each photo by the light-time coding technique, and the exact acquisition time of the photos was obtained. Second, the travel time error was calculated by comparing the time interval between every two images with the standard value. Experimental results indicate that the travel time errors of the hardware trigger and continuous acquisition trigger modesare ±0.1 ms, while the error of the software trigger mode is 32.2 ms. For experiments with high time precision requirement, the hardware trigger and continuous acquisition trigger modes are suggested.