Browsing by Subject "Optical interferometry"

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    Customizing the angular memory effect for scattering media
    (American Physical Society, 2021-07-15) Yılmaz, Hasan; Kühmayer, M.; Hsu, C. W.; Rotter, S.; Cao, H.
    The memory effect in disordered systems is a key physical phenomenon that has been employed for optical imaging, metrology, and communication through opaque media. Under the conventional memory effect, when the incident beam is tilted slightly, the transmitted pattern tilts in the same direction. However, the “memory” is limited in its angular range and tilt direction. Here, we present a general approach to customize the memory effect by introducing an angular memory operator. Its eigenstates possess perfect correlation for tilt angles and directions that can be arbitrarily chosen separately for the incident and transmitted waves, and can be readily realized with wave front shaping. This work reveals the power of wave front shaping in creating any desired memory for applications of classical and quantum waves in complex systems.
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    Far-infrared elastic scattering proposal for the Avogadro Project's silicon spheres
    (Elsevier, 2018) Humayun, M. H.; Khan, I.; Azeem, F.; Chaudhry, M. R.; Gökay, U. S.; Murib, M. S.; Serpengüzel, A.
    Avogadro constant determines the number of particles in one mole of a substance, thus relating the molar mass of the substance to the mass of this substance. Avogadro constant is related to Système Internationale base units by defining the very concept of chemical quantity. Revisions of the base units created a need to redefine the Avogadro constant, where a collaborative work called the Avogadro Project is established to employ optical interferometry to measure the diameter of high quality 100 mm silicon spheres. We propose far-infrared spectroscopy for determining the Avogadro constant by using elastic scattering from the 100 mm Avogadro Project silicon spheres. Similar spectroscopic methods are already in use in the near-infrared, relating whispering gallery modes of the 1 mm silicon spheres to the diameter of the spheres. We present numerical simulations in the far-infrared and the near-infrared, as well as spatially scaled down elastic scattering measurements in the near-infrared. These numerical and experimental results show that, the diameter measurements of 100 mm single crystal silicon spheres with elastic scattering in the far-infrared can be considered as an alternative to optical interferometry.