7. Conclusion

Thanks to advances in the fields of lasers, computers and light-sensitive media, holographic interferometry is now making inroads into the industrial world, particularly for (non-contact) vibration analysis of materials and structures, and stress measurement. The surface area of objects studied can range from a few square millimeters to tens of square meters. Unlike most other methods, deformations can be visualized globally and accurately, and displacements can be measured at any point on the surface with high resolution (0.01 µm). The high sensitivity of the method means that extremely low stresses can be used in non-destructive testing to reveal internal surface defects. Its high spatial resolution (in fact, with a CCD of 500 by 500 pixels, we have the equivalent of 250,000 accelerometers!) enables us to obtain precise spatial derivatives and perform high-performance vibration intensimetry....