This paper investigates correlation between extended source fraction of encircled energy (FEE) and modulation transfer function (MTF) of an optical system from a metrology point of view. Statistics of FEE for a population of lenses was calculated by using a Monte Carlo simulation incorporating manufacturing tolerances. MTF and extended FEE of a group of lenses were measured. The simulation and measured data demonstrates no correlation between extended FEE and MTF signifying the necessity of separate FEE measurement if essential.
Adaptive optics ophthalmic imaging systems that rely on a standalone wave-front sensor can be costly to build and
difficult for non-technical personnel to operate. As an alternative we present a simplified wavefront sensorless adaptive
optics laser scanning ophthalmoscope. This sensorless system is based on deterministic search algorithms that utilize the
image's spatial frequency as an optimization metric. We implement this algorithm on a NVIDIA video card to take
advantage of the graphics processing unit (GPU)'s parallel architecture to reduce algorithm computation times and
approach real-time correction.
We recently developed several versions of a multimodal adaptive optics (AO) retinal imager, which includes highresolution
scanning laser ophthalmoscopy (SLO) and Fourier domain optical coherence tomography (FDOCT) imaging
channels as well as an auxiliary wide-field line scanning ophthalmoscope (LSO). Some versions have also been
equipped with a fluorescence channel and a retinal tracker. We describe the performance of three key features of the
multimodal AO system including: simultaneous SLO/OCT imaging, which allows SLO/OCT co-registration; a small
animal imaging port, which adjusts the beam diameter at the pupil from 7.5 to 2.5 mm for use with small animals
ubiquitous in biological research or for extended depth-of-focus imaging in humans; and slow scan Doppler flowmetry
imaging using the wide field auxiliary LSO imaging channel. The systems are currently deployed in several
ophthalmology clinics and research laboratories and several investigations have commenced on patients with a variety
of retinal diseases and animals in vision research.
The New England Section of the Optical Society of America (NES/OSA), founded in 1949, provides programming for
the promotion of science and optics education. In recent years, the NES/OSA has combined funding to provide
demonstrations during the Massachusetts Science Fairs for Middle and High School age groups and award prizes to the
winners. This funding is supplied from the Section's operating budget, along with grants from the Optical Society of
America (OSA). NES/OSA attends two annual science fairs comprised of the statewide finalists from 6 regional
competitions. During these fairs, NES/OSA members conduct optics demonstrations using the Section's "Optics
Suitcases". This talk will outline the NES/OSA's outreach program, some of the demonstrations and results.
In vivo retinal imaging is an outstanding tool to observe biological processes unfold in real-time. The ability to image
microstructure in vivo can greatly enhance our understanding of function in retinal microanatomy under normal conditions and in disease. Transgenic mice are frequently used for mouse models of retinal diseases. However, commercially available retinal imaging instruments lack the optical resolution and spectral flexibility necessary to visualize detail comprehensively.
We developed an adaptive optics scanning laser ophthalmoscope (AO-SLO) specifically for mouse eyes. Our SLO is a sensor-less adaptive optics system (no Shack Hartmann sensor) that employs a stochastic parallel gradient descent algorithm to modulate a deformable mirror, ultimately aiming to correct wavefront aberrations by optimizing confocal image sharpness.
The resulting resolution allows detailed observation of retinal microstructure. The AO-SLO can resolve retinal microglia
and their moving processes, demonstrating that microglia processes are highly motile, constantly probing their immediate environment. Similarly, retinal ganglion cells are imaged along with their axons and sprouting dendrites.
Retinal blood vessels are imaged both using evans blue fluorescence and backscattering contrast.
In studying retinal disease on a microscopic level, in vivo imaging has allowed researchers to track disease
progression in a single animal over time without sacrificing large numbers of animals for statistical studies.
Historically, a drawback of in vivo retinal imaging, when compared to ex vivo imaging, is decreased image
resolution due to aberrations present in the mouse eye.
Adaptive optics has successfully corrected phase aberrations introduced the eye in ophthalmic imaging in
humans. We are using adaptive optics to correct for aberrations introduced by the mouse eye in hopes of
achieving cellular resolution retinal images of mice in vivo. In addition to using a wavefront sensor to drive
the adaptive optic element, we explore the using image data to correct for wavefront aberrations introduced by
the mouse eye. Image data, in the form of the confocal detection pinhole intensity are used as the feedback
mechanism to control the MEMS deformable mirror in the adaptive optics system. Correction for wavefront
sensing and sensor-less adaptive optics systems are presented.
The focused radially polarized Cylindrical Vector (CV) beam has been found to have a strong longitudinal field component at focus in the direction of propagation of the beam. It has been shown that this field component can be used to excite a second harmonic (SH) signal at a surface interface. Th spatial intensity profile that excites the SH signal has ben predicted to have a smaller lateral extent than a similarly focused linearly polarized beam. The possibility to use this longitudinal field component for SH surface imaging is investigated.
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