范围–传统的测光方法依赖于使用测角仪以直角绕两个轴旋转测试项目。这种方法在大多数情况下都是令人满意的，但也有一些缺点:a.用测角仪逐点测量可能很慢。随着对前照灯的要求越来越高，尤其是对前照灯的要求越来越高，因此需要对整个光束模式进行测量。这样的测试可能非常耗时。b、 为了保证生产质量，如果必须对大量灯具进行取样，测角仪的速度可能不允许测试与生产线同步。c、 高强度气体放电灯（HID）正变得越来越普遍。这种灯对方向敏感，倾斜时流明输出和强度分布都会发生变化。 当使用测角仪进行测试时，这可能会导致测试结果的严重不准确。需要替代测试技术，以实现非常高速的数据采集、捕获完整的等轴分布，并消除灯倾斜。本SAE信息报告描述了解决这些问题的基于视频的测试的基本原理。需要更多信息来提供使用这些技术建立实验室所需的所有细节。在基于视频的系统中，灯固定在适当的位置，对准接收屏幕。特定类型和等级的摄像头可以查看屏幕，并能够测量屏幕上每个点的反射光（亮度）。 系统的适当校准可以根据测量的亮度值提供被测光的发光强度分布。为了产生一个精确的测量系统，必须考虑许多因素。在受控条件下，该系统可以产生具有良好精度的绝对强度分布测量。（参考2.1.1和2.1.2。）这种光度法的最大优点是其极高的速度，可以在不到一分钟的时间内收集等山形图。还有一些附带的缺点将在后面讨论。本文件描述了准确度所需的基本技术和控制措施。还提供了将基于视频的技术与传统测角仪方法进行比较的评论。

Scope—Traditional methods of photometry rely on the use of a goniometer to rotate the test item around two axes at right angles. This method is satisfactory for most situations but has certain disadvantages: a. Point-by-point measurements with a goniometer may be slow. With more advanced requirements, particularly for headlamps, where the entire beam pattern is of concern, isocandela measurements are becoming increasingly needed. Such testing can be very time consuming. b. For production quality assurance, the speed of a goniometer may not allow testing to keep pace with the production line if a large quantity of lamps must be sampled. c. High Intensity Discharge (HID) lamps are becoming commonly used. Such lamps are orientation sensitive, changing in both lumen output and intensity distribution when tilted. This can introduce significant inaccuracies in test results when testing is performed using a goniometer. There is a need for alternative test techniques which can achieve very high speed data acquisition, the capture of full isocandela distribution, and the elimination of lamp tilting. This SAE Informational Report describes fundamentals of video-based testing to address these concerns. Further information is required to provide all details needed to set up a laboratory using these techniques. With the video-based system, the lamp is fixed in position and aimed at a receiving screen. A camera, of particular type and grade, views the screen and is able to perform measurement of the reflected light (luminance) at each point on the screen. Proper calibration of the system can provide the luminous intensity distribution of the light under test from the measured luminance values. Numerous factors must be taken into account to produce an accurate measurement system. Under controlled conditions, it has been shown that the system can produce measurement of absolute intensity distributions with good accuracy. (Reference 2.1.1 and 2.1.2.) The great advantage of this form of photometry is its extremely high speed, allowing the collection of isocandela diagrams in less than one minute. There are some accompanying disadvantages which are discussed later. This document describes the basic techniques and the controls which are necessary for accuracy. Comments are also provided comparing video based technology to conventional goniometer methods.