The demand for widefield OCTA is growing as many retinal diseases exhibit alterations in the peripheral microvascular network at the early stage. In this work, we demonstrate ultrawide-field retinal OCTA over the area spanning 20 mm in diameter in 5 seconds using a 4.74 MHz A-line rate stretched-pulse mode locking (SPML)-OCT system. A concentric-circular scanning with an automatic reference arm length adjustment enabled a wide-field and large-curvature retina imaging within a 2 GHz signal bandwidth. The automatic focal plane adjustment and the deep learning-based denoising were also utilized to enhance vessel visualization in ultrawide-field OCTA images.
Three-dimensional (3D) cellular-resolution imaging of the living human retina over a large field of view would bring a great impact in clinical ophthalmology, potentially finding new biomarkers for early diagnosis and improving the pathophysiological understanding of ocular diseases. While hardware-based and computational Adaptive Optics (AO) Optical Coherence Tomography (OCT) have been developed to achieve cellular-resolution retinal imaging, these approaches support limited 3D imaging fields and their high cost, and their intrinsic hardware complexity limit their practical utility. Here, we demonstrate 3D depth-invariant cellular-resolution imaging of the living human retina over a 3-mm × 3-mm field of view using the intrinsically phase-stable multi-MHz retinal swept-source OCT and tailored computational defocus and aberration correction methods. Single-acquisition imaging of photoreceptor cells, retinal nerve fiber layer, and retinal capillaries is presented across unprecedented imaging fields. By providing wide-field 3D cellular-resolution imaging in the human retina using a standard point-scan architecture routinely used in the clinic, this platform proposes a strategy for expanded utilization of high-resolution retinal imaging in both research and clinical settings.
In vivo computational adaptive optics optical coherence tomography (CAO-OCT) has been challenging due to insufficient volume scan rate. We present video-rate volume-scanning CAO-OCT with a multi-MHz stretched-pulse mode-locked laser.
OCT angiography (OCTA) has recently garnered immense interest in clinical ophthalmology, permitting ocular vasculature to be viewed in exquisite detail, in vivo, and without the injection of exogenous dyes. However, commercial OCTA systems provide little information about actual erythrocyte speeds; instead, OCTA is typically used to visualize the presence and/or absence of vasculature. This is an important limitation because in many ocular diseases, including diabetic retinopathy (DR) and age-related macular degeneration (AMD), alterations in blood flow, but not necessarily only the presence or absence of vasculature, are thought to be important in understanding pathogenesis. To address this limitation, we have developed an algorithm, variable interscan time analysis (VISTA), which is capable of resolving different erythrocyte speeds. VISTA works by acquiring >2 repeated B-scans, and then computing multiple OCTA signals corresponding to different effective interscan times. The OCTA signals corresponding to different effective interscan times contain independent information about erythrocyte speed. In this study we provide a theoretical overview of VISTA, and investigate the utility of VISTA in studying blood flow alterations in ocular disease. OCTA-VISTA images of eyes with choroidal neovascularization, geographic atrophy, and diabetic retinopathy are presented.
The inherent control flexibility implied by solid-state lighting - united with the rich details offered by sensor
networks - prompts us to rethink lighting control. In this research, we propose several techniques for measuring
work surface illuminance and ambient light using a sensor network. The primary goal of this research is to
measure work surface illuminance without distraction to the user. We discuss these techniques, including the
lessons learned from our prior research. We present a new method for measuring the illuminance contribution
of an arbitrary luminaire at the work surface by decomposing the modulated light into its fundamental and
harmonic components.
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