Laser light interference

This direct approach allows one to calculate the calibration factors with an error of —5%. As shown, the approach is not affected by an additional small sample tilt, different feedback settings, and a possible tip position off the central cantilever axis. Only laser light interference and nonspherical tip apex shapes must be taken into account. It is pointed out that the laser alignment of each tip used should not be altered throughout the experiments, as this would also introduce relative errors. For a more detailed discussion, the reader is referred to [28]. 

In friction force microscopy, laser light interference may lead to artefacts that are often eliminated by subtracting trace and retrace (after scan line shift correction). 

Thermal expansion was measured by the laser light interference method. 

The advent of lasers allowed optical interferometry to become a useful and accurate technique to determine surface motion in shocked materials. The two most commonly used interferometric systems are the VISAR (Barker and Hollenbach, 1972) and the Fabry-Perot velocity interferometer (Johnson and Burgess, 1968 Durand et al., 1977). Both systems produce interference fringe shifts which are proportional to the Doppler shift of the laser light reflected from the moving specimen surface. Both can accommodate a speci-... 

Fig.1 A modern analytical nltracentrifuge. a Beckman Optima XLA/I, with full on-line data captnre and analysis facility, b Its UV/visible monochromator and, for interference optics, the laser light sonrce are contained in the rotor chamber and have to be installed and removed at the start/end of each rnn...

An experimental method based on the theories for rainbow phenomena has been applied to the measurement of droplet size and velocity and to the detection of non-sphericity.[7] In this method, a comparison between two droplet diameters is deduced from two different optical interference patterns observed in a rainbow that is created by a droplet scattering laser light. Once a rainbow pattern is... 

This effective Q,t-range overlaps with that of DLS. DLS measures the dynamics of density or concentration fluctuations by autocorrelation of the scattered laser light intensity in time. The intensity fluctuations result from a change of the random interference pattern (speckle) from a small observation volume. The size of the observation volume and the width of the detector opening determine the contrast factor C of the fluctuations (coherence factor). The normalized intensity autocorrelation function g Q,t) relates to the field amplitude correlation function g (Q,t) in a simple way g t)=l+C g t) if Gaussian statistics holds [30]. g Q,t) represents the correlation function of the fluctuat-... 

Another important optical phenomena that relies on light interference and diffraction is holography, the process by which holograms (interference patterns) are produced. Whilst holograms are best known for the reproduction of near perfect 3D images of an object in the graphic arts, they also find apphcations in newer areas such as laser eye protection, LCDs, diffractive optical elements, optical processing... 

Only much later it was realized that the excellent coherence of laser light offers another, maybe much more powerful control parameter, which allows us to make use of quantum mechanical interference. This principle forms the basis of what is today generally referred to as coherent control. 

Fig. 8.2.1. Low angle laser light scattering photometer (Chromatix KMX-6) simplified optical diagram. 1 Flelium-neon laser 2 prism system 3,4,5 measuring attenuators 6 calibrating/ shutter attenuator 7 condensing lens 8 sample compartment 9 annuli 10 safety attenuator 11 relay lens 12 field stops 13 interference filter 14 analyzing polarizer 15 microscope objective 16 photomultiplier...

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