All S/H systems change with time and use. Therefore, a calibration procedure for evaluating the operation of an S/H system is desirable. This calibration procedure provides a method of obtaining an optimized interferometric image pattern associated with a given size anomaly.

The use of straining blocks as calibration devices provides a means for ensuring the continued optimal performance of the S/H system. Straining blocks can also be used to compare performance of S/H systems in different facilities.

At not greater than a three (3) month interval the S/H system shall be calibrated following the procedures described in this practice. When necessary, adjustments, repairs, or modifications shall be made to the S/H system until it is able to observe, in the same image, all anomalies of size within the range of interest contained in the straining blocks.

1.1 This standard practice describes the construction and use of a calibration device for demonstrating the anomaly detection capability of interferometric laser imaging nondestructive tire inspection system. A common practice within the industry is to refer to these systems as shearographic/holographic (S/H) systems.

1.2 This standard practice applies to S/H systems that are used for evaluating the structural integrity of pneumatic tires, (for example, presence or absence of anomalies within the tire).

1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.