Digital in-line holography and the numerical reconstruction of holograms
LE3 .A278 2014
Bachelor of Science
A hologram is the recorded interference pattern between a reference wave and a scattered wave from an object. Although, the recording medium only captures the intensity of the light from these waves, the information about both the amplitude and the phase is still present in this recording, due to the interference fringes produced by the superposition of these two waves. This information can be reconstructed numeri-cally using the Fresnel-Kirchoff integral, which can be transformed into a numerically efficient calculation using the convolution theorem. The setup used in this thesis was in-line holography. In Digital In-line Holographic Microscopy (DIHM), all of the components are aligned in a linear setup, and both the reference and scattered waves are recorded on the same detector. The setup used in this thesis contained a laser, two objective lenses, the object holder, a neutral density (ND) filter, and a charged coupled device (CCD). The CCD allowed for direct digital recording of the holograms. Once the holograms were obtained from the DIHM, an open-source Python library, HoloPy, was used to reconstruct the holographic images. Images from both Harvard and Acadia Universities were recorded and reconstructed, which demonstrated the successful acquisition of holograms and the reconstruction method. The DIHM that was constructed at Acadia achieved a resolution of approximately 2.7 μm.
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