Optical structural health monitoring

A method for conducting structural health monitoring of a substrate, comprising:

• a) designating a substrate or portion thereof to be monitored;
• b) applying a pattern on the substrate or portion thereof that comprises one or more of a design element or background provided on one or more locations on the surface of the substrate or portion thereof;
• c) imaging the pattern with equipment that captures the image of the pattern;
• d) storing the image captured in step c);
• e) wherein the pattern applied comprises a pattern of discrete elements which is applied to form the one or more of a design element or background by pointillism, and wherein the substrate or portion thereof is imaged with said imaging equipment to identify strains and deformations of the substrate at the one or more locations of the substrate or portion thereof where the said one or more pointillized design element or background is applied;
• f) including determining from the imaging the presence of or the extent of strain or deformation of the substrate or an area of the substrate or portion thereof at the one or more locations of the substrate or portion thereof where the pointillized design element or background is applied, and
• g) wherein determining the presence of or the extent of strain or deformation is carried out on a substrate that is or comprises an in service object.