Applying deflectometry techniques to non-reflective planar panels using add-on reflective material

Reflected grid deflectometry is an optical method of vibration analysis relying on specular reflections to create amplifications of measured deformations in a planar test structure, resulting in high resolution slope and deflection plots of the test surface. Therefore, the structure under test is required to have a reflective surface. Application has so far been limited to ideal mirror-finished planar objects. An experiment is constructed to test the effectiveness of add-on reflective material on non-reflective planar panels for deflectometry measurements, using a collection of adhesive tapes, film, and spray. The structural deflection due to a point impact is measured, and results for each add-on material are then compared and discussed. The findings indicate that tapes, while cheap, are manufactured without strict tolerances on thickness, causing distortions in the reflected image and therefore the deflection plots. Film can be applied with limited success, but further testing is required to refine the application method. Spray-on reflective material, which is only applicable on transparent surfaces, produces deflection plots comparable in quality to those of an ideal mirror.