基于视频的光测量技术

[中文适用范围]： 传统的光度测量方法依赖于使用测角仪围绕两个轴以直角旋转测试项目。这种方法对于大多数情况来说是令人满意的，但有一定的缺点：使用测角仪进行逐点测量可能会很慢。随着更先进的要求@特别是对于头灯@，其中整个光束图案都受到关注@等光强测量变得越来越需要。此类测试可能非常耗时。 b.为了保证生产质量@，如果必须对大量灯进行采样，则测角仪的速度可能无法使测试跟上生产线的步伐。 C。高强度放电 (HID) 灯越来越普遍使用。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显着不准确。需要替代的测试技术来实现非常高速的数据采集@捕获完整的等光强分布@并消除灯倾斜。这份 SAE 信息报告描述了基于视频的测试的基本原理，以解决这些问题。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详细信息。使用基于视频的系统@，灯被固定在适当的位置并瞄准接收屏幕。特定类型和等级的相机@观察屏幕并能够测量屏幕上每个点的反射光（亮度）。对系统进行适当的校准可以根据测量的亮度值提供被测光的发光强度分布。为了产生精确的测量系统，必须考虑许多因素。事实证明，在受控条件下，该系统可以高精度地测量绝对强度分布。 （参考文献 2.1.1 和 2.1.2。）这种光度测定形式的最大优点是其极高的速度，可以在一分钟内收集等光强图。有一些伴随的缺点，稍后讨论。本文档描述了准确性所需的基本技术和控制。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。背景和历史？整个光分布的测量成为 20 世纪 60 年代的一个研究主题，当时胶片相机被用来进行光度测量。 （参考文献 2.1.3。） 奠定的基础表明，如果问题的主要根源@胶片本身@可以被更稳定和可靠的图像收集方法所取代，那么摄影测光将是一种可行的技术。随着电荷耦合器件@ (CCD)@ 的出现，胶片相机的大部分问题都得到了解决。然而，为了生产精确的光度测量系统@，必须了解 CCD 相机系统的特性。必须采用正确的校准方法并进行控制以确保准确性。 [外文原描述]： 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:aPoint-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.bFor 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.cHigh 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.Cross Reference: 960919,970231