Conventional line-of-sight imaging techniques rely on detecting light paths bouncing from the object and reaching directly to the detector. Absence of any such direct light paths from object to detector results in a failure to recover any useful information using conventional techniques. The absence of direct light paths from object to detector can be observed in several real-world scenarios such as looking around a corner, imaging through turbid media, imaging through tissue etc.
The focus of this thesis is pertaining to the problem of looking around corners (or) imaging object hidden from line of sight at macroscopic scales. This thesis focuses on adapting heterodyne interferometry to circumvent the radiometry losses due to scattering and thereby enabling its use in more challenging practical scenarios. Objects hidden around a corner were reconstructed with 500 µm resolution at 0.8 meters standoff. Using heterodyne interferometry and lock-in detection techniques, the hologram of the hidden object could be obtained even under significant radiometry losses without any power matching. Also discussed is the estimation of rapidly varying and slowly varying motion of objects around a corner using doppler shifts and speckle correlations respectively.
Electrical and Computer Engineering
Dr. Marc Christensen
Dr. Prasanna Rangarajan
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Madabhushi Balaji, Muralidhar, "Indirect Imaging using Heterodyne Remote Digital Holography" (2018). Electrical Engineering Theses and Dissertations. 22.