Advancing Compact, Multiplexed, and Wavefront-Controlled Designs for Coherent Optical Systems

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The development of non-invasive retinal imaging systems has revolutionized the care and treatment of patients in ophthalmology clinics. Using high-resolution modalities such as scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT), physicians and vision scientists are able detect previously unseen features on the subject retina which can 1) provide information for diagnosis, 2) identify disease biomarkers, 3) inform treatment or clinical trial regimens, and 4) improve understanding of underlying disease processes. Traditional SLO and OCT devices are designed as tabletop systems which are unable to accommodate vulnerable populations including intrasurgical patients and young children. Thus, the miniaturization of these systems into compact, handheld form factors is of great interest in both biomedical optics/imaging and medical research fields as they are essential to the proper care of patients. Previous studies have shown that handheld systems are instrumental in assessing overall health of young children and disease progressions in subjects of all ages. However, handheld systems are limited in optical performance as hardware selection is restricted to components of small size and low weight. Additionally, aberrations induced by both the system optics and the human eye degrade the resolution of the images. This work focuses on the integration of adaptive optics (AO) technology into handheld form factors to correct for aberrations and provide in vivo visualization of single cells such as cone photoreceptors and retinal pigment epithelium cells. We present two devices which demonstrate the first ever dual-modality AO-SLO and AO-OCT handheld imaging devices that push the limits of comprehensive, cellular-resolution retinal imaging. Finally, we investigate the use of 3x3 fused fiber couplers as a simple, compact coherent receiver design. Our novel balanced-detection topology achieves shot-noise limited performance in the presence of excess noise and shows improved SNR as compared to previous implementations. We detail its ability to enable instantaneous quadrature projection for applications in LiDAR, phase imaging, and optical communications.





Hagan, Kristen Elizabeth (2023). Advancing Compact, Multiplexed, and Wavefront-Controlled Designs for Coherent Optical Systems. Dissertation, Duke University. Retrieved from


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