Laser interference patterning system

Commercial polymer films can be easily microstructured using Laser Interference Patterning. In that way, the scope of the technique is increased since materials having well-known bulk and surface properties can be microstructured, allowing direct application, for example, in biomedical devices poly(etheretherketone) resists sterilization by radiation or heat treatment and it has been used to produce kidney dialysis machine components poly(etherimide) is used in harmonic scalpels polycarbonate (PC) is used in electrophysiology cathethers and poly(imide) (PI) is used in off pump coronary artery bypass devices.Moreover, the surface of already fabricated systems could be modified using this technique since it can be applied in air without altering the shape of the samples. 

At the sample stage, a flat mirror is mounted perpendicular to the sample on a rotation stage. As part of the laser beam is reflected by the mirror, it interferes with the nonreflected part to form an interference pattern on the photoresist. The period P is given as P = where 6 is the incident angle [44]. After lithography and baking, the templates are then transferred into an electron-beam or a thermal evaporation thin film deposition system for metallization. As the thickness of the metal film is larger than the skin depth of metal, the metallic arrays are considered as semi-infinitely thick. 

In an interference optical system, coherent light from a laser is split into two beams. One is passed through the sample, and the other through the reference sector. The beams are then recombined and a pattern of fringes is created by constructive or destructive interference of the light waves. If one beam is slowed by higher refractivity of the sample, the fringe pattern will be shifted from a central reference position. This displacement is related to the sample concentration by... 

Refractive index detection A microvolume refractive index detection method has been developed for CE consisting of a micro-interferometer back-setter system, illuminated by a He-Ne laser giving a characteristic interference pattern. The change of such a pattern is due to the change of the refractive index caused by the separated substance. This detection system was tested for the separation of mono- and oligosaccharides. 

FIGURE 20 (a) Laser interference grating recording system, (b) Details of interference light pattern. 

Ring Lasers and Gyroscopes. In the last few decades, laser interferometers have started to replace mechanical gyroscopes in many aircraft navigation systems. In these interferometers, the laser light is reflected off of mirrors such that the two beams travel in opposite directions to each other in a ring, recombining to produce an interference pattern at... 

Speckle A sparkling effect in a laser beam projection system resulting from interference patterns in coherent light. 

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