概述了测量VGI的实验室技术，并就设备主要子单元的性能提出了建议。规定试验条件和表达结果的标准方法。提供VGI测量设备的操作指南，以便于获得准确的结果。

Laboratory techniques for measuring VGI are described in general terms and recommendations are made regarding the performance of the main subunits of the equipment. Standard methods of specifying conditions of test and of expressing the results. Gives guidelines for the operation of VGI measuring equipment to facilitate the obtaining of accurate results.