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 Remendations issued by the World Trade Organization Technical Barriers to Trade (TBT)Committee. Designation:F2469-20 INTERNATIONAL Standard Test Method for Measuring Optical Angular Deviation of Transparent Parts Using the Double-Exposure Method This standard is issued under the fixed designation F2469 the number immediately following the designation indicates the year of original adoption or in the case of revision the year of last revision.A number in parentheses indicates the year of last reapproval.A superseript epsilon (e)indicates an editorial change since the last revision or reapproval. 1.Scope 3.Terminology 1.1 This test method covers the measurement of the optical 3.1 Definitions: angular deviation of a light ray imposed by flat transparent 3.1.1 angular deviation n-the angular displacement of a parts such as a mercial or military aircraft windshield light ray from its original path caused by non-parallelism of canopy or cabin window. opposite surfaces as it passes through a transparent material 1.2 The values stated in SI units are to be regarded as which is expressed in units of angle (degree minutes of arc standard.No other units of measurement are included in this milliradians)and is a function of the angle of incidence at each standard. s...