Coherence and speckle techniques for imaging through highly scattering media and optical fibers.

Holographic time gating (first arriving light) methods have been shown to be an effective way to image through highly scattering media, yet, the holographic method has the problem of placing the signal of interest on a large bias term, making the signal susceptible to noise. A complete noise analysis of the electronic holography time gating system is performed. Analytical expressions for the signal-to-noise ratio due to the dominant noise terms are derived and the effect of various system parameters on the signal-to-noise ratio is explored. Because the holographic first arriving light method is highly susceptible to noise, it is essential that optical system noise be reduced; this can be a tedious task therefore, a post processing method capable of removing fixed additive system noise is described and implemented. A detection enhancement speckle technique providing increased sensitivity to moving objects embedded within a stationary scattering medium is presented. This method is combined with the first arriving light method to create a synergistic effect, enhancing both sensitivity and resolution when imaging through highly scattering media. This concept is extended to distinguishing between various types and rates of motion through multiframe processing. A combined statistical averaging/first arriving light technique is described for phase recovery through highly scattering media. This ensemble phase information is used to enhance the time gated image by a deconvolution process. Analogous to time gating temporal coherence processes there exist spatial gating spatial coherence processes. These spatial gating methods are used to implement a direct three dimensional image fiber transmission system. An enhanced system allowing both the reference beam and the object beam to be confined to single mode fibers is also described and demonstrated. The fiber transmission system is presented from various points of view, including a general data communications approach where the system performance is analyzed in terms of data rate, probability of bit error, and modulation schemes. The spatial coherence imaging concept is extended to create a generalized optical crossbar switch.Ph.D.Applied SciencesElectrical engineeringOpticsPure SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/130553/2/9732152.pd