Physics – Optics
Scientific paper
2009-07-20
Physics
Optics
Ph. D. thesis
Scientific paper
Elastic light scattering has been extensively used to study samples showing a non uniform refraction index on lengthscales from a fraction of a micrometer to a fraction of a millimeter. Typically, a wide laser beam is sent through the sample, and the light scattered at any angle is measured by a detector in the far field. In this Ph. D. thesis, I describe three new techniques, which allow to measure the scattering intensities, working in the near field: hOmoyne Near Field Speckles (ONFS), hEterodyne Near Field Speckles (ENFS) and Schlieren-like Near Field Speckles (SNFS). Basically, the experimental setup consists in a wide laser beam passing through the sample; a lens forms an image of a plane at a given distance from the cell on a CCD sensor. The image, in the near field, shows speckles, since it is formed by the stochastical interference of the light coming from a random sample. I show that, under suitable conditions, the correlation function of such a field closely mirrors the correlation function of the investigated sample; moreover, in general, from the correlation function of the speckle field it is possible to calculate the scattered intensity. I present for the first time a mathematical derivation of the working formulas for the three techniques, and experimental results.
No associations
LandOfFree
Near Field Speckles does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Near Field Speckles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Near Field Speckles will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-696189