A simple technique to reshape the response of tapped delay line photonic microwave filters is demonstrated. The technique is based on the generation and control of a set of optical carriers by means of four-wave mixing. Experimental results show reconfiguration from 2 to 5 taps with uniform and apodized amplitude distributions.
Corneal biomechanics play a fundamental role in the genesis and
progression of corneal pathologies, such as keratoconus; in corneal
remodeling after corneal surgery; and in affecting the measurement
accuracy of glaucoma biomarkers, such as the intraocular pressure
(IOP). Air-puff induced corneal deformation imaging reveals
information highlighting normal and pathological corneal response to a
non-contact mechanical excitation. However, current commercial systems
are limited to monitoring corneal deformation only on one corneal
meridian. Here, we present a novel custom-developed swept-source
optical coherence tomography (SSOCT) system, coupled with a collinear
air-puff excitation, capable of acquiring dynamic corneal deformation
on multiple meridians. Backed by numerical simulations of corneal
deformations, we propose two different scan patterns, aided by low
coil impedance galvanometric scan mirrors that permit an appropriate
compromise between temporal and spatial sampling of the corneal
deformation profiles. We customized the air-puff module to provide an
unobstructed SSOCT field of view and different peak pressures,
air-puff durations, and distances to the eye. We acquired
multi-meridian corneal deformation profiles (a) in healthy human eyes
in vivo, (b) in porcine eyes ex vivo under varying controlled IOP, and (c) in
a keratoconus-mimicking porcine eye ex
vivo. We detected deformation asymmetries, as predicted by
numerical simulations, otherwise missed on a single meridian that will
substantially aid in corneal biomechanics diagnostics and pathology
screening.
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