1.1 该定量测试方法包括主应变方向ε的测量 1. 和ε 2. 和光弹性延迟δ，使用补偿器，用于分析透明或半透明塑料材料中的应变。该测试方法可用于测量双折射，并在主方向在光路内基本不变时确定主应变或法向应变的差异。 1.2 除了本试验方法中描述的使用补偿器的方法外，还使用其他方法，例如测角法（使用分析仪的旋转），主要用于测量小延迟，并将其表示为波长的一部分。采用分光光度测量和消除人类判断因素的非视觉方法也是可能的。 1.3 通过该试验方法获得的试验数据是相关的，适用于工程设计。 1.4 以国际单位制或英寸磅单位表示的数值应视为标准值。每个系统中规定的值可能不完全相等；因此，每个系统应独立使用。将两个系统的值合并可能导致不符合标准。 1.5 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践，并确定监管限制的适用性。 注1: 没有已知的ISO等效于此测试方法。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 5.1 透明或半透明材料中应变的观察和测量被广泛用于实验应力分析的各种建模技术中。 5.2 可评估制造过程（如铸造、成型、焊接、挤压和聚合物拉伸）中产生的内部应变，并识别出过度应变的零件。此类测量可导致缺陷零件的消除、工艺改进、退火操作的控制等。 5.3 当测试物理性能时，需要对试样进行偏光检查，以消除出现异常内部应变水平（或缺陷）的试样。例如:测试方法 D638型 （注8）和 D882型 （注11）建议进行偏光检查。 5.4 取向聚合物的双折射可以与取向、收缩等有关。 双折射的测量有助于这些聚合物的表征。 5.5 对于许多材料，可能有一个规范要求使用该试验方法，但在遵守规范时，一些程序修改优先。因此，在使用该试验方法之前，建议参考该材料规范。分类系统表1 4000美元 列出了当前存在的ASTM材料标准。

1.1 This quantitative test method covers measurements of direction of principal strains, ε 1 and ε 2 , and the photoelastic retardation, δ, using a compensator, for the purpose of analyzing strains in transparent or translucent plastic materials. This test method can be used to measure birefringence and to determine the difference of principal strains or normal strains when the principal directions do not change substantially within the light path. 1.2 In addition to the method using a compensator described in this test method, other methods are in use, such as the goniometric method (using rotation of the analyzer) mostly applied for measuring small retardation, and expressing it as a fraction of a wavelength. Nonvisual methods employing spectrophotometric measurements and eliminating the human judgment factor are also possible. 1.3 Test data obtained by this test method is relevant and appropriate for use in engineering design. 1.4 The values stated in either SI units or inch-pound units are to be regarded as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Note 1: There is no known ISO equivalent to this test method. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 The observation and measurement of strains in transparent or translucent materials is extensively used in various modeling techniques of experimental stress analysis. 5.2 Internal strains induced in manufacturing processes such as casting, molding, welding, extrusion, and polymer stretching can be assessed and parts exhibiting excessive strains identified. Such measurements can lead to elimination of defective parts, process improvement, control of annealing operation, etc. 5.3 When testing for physical properties, polariscopic examination of specimens is required, to eliminate those specimens exhibiting abnormal internal strain level (or defects). For example: Test Methods D638 (Note 8) and D882 (Note 11) recommend a polariscopic examination. 5.4 The birefringence of oriented polymers can be related to orientation, shrinkage, etc. The measurements of birefringence aid in characterization of these polymers. 5.5 For many materials, there may be a specification that requires the use of this test method, but with some procedural modifications that take precedence when adhering to the specification. Therefore, it is advisable to refer to that material specification before using this test method. Table 1 of Classification System D4000 lists the ASTM materials standards that currently exist.