Shearography as part of a multi-functional sensor for the detection of signature features in movable cultural heritage

This is one of a series of papers submitted by the Multi-Encode Project consortium (006427 (SSPI)). Shearography, a full-field speckle interferometry technique, is applied to the investigation of movable cultural heritage. For this project a portable shearography sensor was developed, with conventional sensor hardware supported by novel algorithms and instrument control software. The sensor has been used for an extensive measurement program, the purpose of which is to develop an Impact Assessment Procedure; this is to determine the capabilities of a shearography sensor in this measurement application. Data from the sensor, which shows the location of defects in the artwork, is stored in a database for future analysis and comparison. The particular advantages identified for incorporating shearography in a multi-functional sensor are the ability to measure unstable objects, such as gently vibrating canvas paintings, adjustable interferometric sensitivity and a different sensitivity parameter (displacement gradient) to the other sensors investigated. This work will assist in fulfilling the aims of the project, the detection of signature features for security purposes and the study of changes in artwork for conservation purposes.