Date of Award

9-1-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Engineering Physics

First Advisor

Glen P. Perram, PhD

Abstract

Digital holography (DH) uses coherent detection and offers direct access to the complex-optical field to sense and correct image aberrations in low signal-to-noise environments, which is critical for tactical applications. The performance of DH is compared to a similar, well studied deep-turbulence wavefront sensor, the self-referencing interferometer (SRI), with known efficiency losses. Wave optics simulations with deep-turbulence conditions and noise were conducted and the results show that DH outperforms the SRI by 10's of dB due to DH's strong reference. Additionally, efficiency experiments were conducted to investigate DH system losses. The experimental results show that the mixing efficiency (37%) is the dominate efficiency loss; however, excess reference noise (75%) and excess signal noise (3%-100%) are significant efficiency losses as well. Further experiments show DH effectively quantifies laser coherence as an efficiency to within ±3:2% of the spectral models and the observed laser coherence can be dependent on the hologram integration time. The observed laser linewidth was reduced 65% by decreasing the integration time from 100 ms to 100 µs, thus filtering laser frequency noise and increasing the effective system range by 280%.

AFIT Designator

AFIT-ENP-DS-19-S-029

DTIC Accession Number

AD1084615

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