5.1 The transmittance of an attenuating medium can cause errors for an infrared thermographer using an infrared imaging radiometer to measure the temperature of a specimen through the medium. Three test methods are given for measuring and compensating for this error source.

5.1.1 A procedure is given for measuring the transmittance of an attenuating medium.

5.1.2 A procedure is given for compensating for errors when measuring the temperature of a specimen having a known emissivity through an attenuating medium with a known transmittance.

5.1.3 A procedure is given for measuring and compensating for transmittance and emissivity errors when the specimen temperature is known.

5.2 These procedures can be used in the field or laboratory using commonly available materials.

5.3 These procedures can be used with any infrared radiometers that have the required computer capabilities.

5.4 The values of transmittance are defined only in terms of the procedure for the purpose of process control and nondestructive evaluation of materials.

1.1 This practice covers procedures for measuring and compensating for transmittance when using an infrared imaging radiometer to measure the temperature of a specimen through an attenuating medium, such as a window, filter, or atmosphere.2

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 These procedures may involve use of equipment and materials in the presence of heated or electrically-energized equipment, or both.

1.4 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.

1.5 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.