What is holographic interferometry?
holographic interferometry is a measurement technique that studies changes in the surface structure of the building. Laser light reflecting from the building is recorded in the hologram as a three -dimensional record later reconstructed in precisely detail. This record can be compared to the original object or other holographic exhibitions of this object. In comparison, the surface change will be marked with marginal or striped interference patterns. These formulas are formed when light waves reflect the object differ due to the displacement of the surface and interfere with each other.
The use of holograms gives this unique advantage over conventional optical interferometry methods. Structural changes can be studied in direct comparison of holograms made from the building at different times under different conditions. The recorded information is the entire surface of the object. The effects of moving the object as a whole can then be observed.
There are three basic methods of interferometry. These include real -time, multiple exposure and average methodsy. Lasers can be used almost any wavelength. Continuous lasers are usually used to investigate surface changes and real -time movement. Pulse lasers are best used to study rapidly changing phenomena.
Holographic interferometry in real time allows immediate observation of small changes in the object because it is subjected to stress. The hologram of the object to be studied overlaps over the object itself. If the object is now subjected to stress factors, any deformation on the surface will be observed as marginal interference formulas. Measurement of these formulas reveals the size and direction of deformation in accurate details.
Techniques of more exposure use two or more holographic exposures. Initial hologram is an object at rest. Other exposures are made and recorded in the same image, because the studied object is subjected to a specific stress factor. The final holographic imageDisplays a change in the surface shift during testing. Pulse lasers can be timed for recording critical test intervals or changes in the state of the object in a state.
In the average method, a hologram is created, while the object is exposed to periodic than continuous stress. The result is an image of the object formula. Holographic interferometry allows very accurate measurement of complex vibration patterns.
Each of these methods shows the shape, size and direction of the surface shift. The accuracy of holographic interferometry allows the collection of meaningful data from non -destructive testing. As a result, the technique is particularly suitable for quality control. Accurate data maintenance in holographic form allows easy conversion to digital format and computer examination.