Duncan L. MacFarlane

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A novel brush optode was designed and demonstrated to overcome poor optical contact with the scalp that can occur during functional near infrared spectroscopy (fNIRS) and imaging due to light obstruction by hair. The brush optodes were implemented as an attachment to existing commercial flat-faced (conventional) fiber bundle optodes. The goal was that the(More)
A true three-dimensional monitor is being developed for the direct display of three- (or higher-) dimensional information. The device is constructed of a three-dimensional array of pixels, actually voxels or volume elements, which in their quiescent state are transparent. When these elements are excited optically through a fiber-optic pigtail, they(More)
An optical coupler for integrated photonic circuits is presented and analyzed. The coupler is based on frustrated total internal reflection (FTIR) and offers high efficiency in a compact footprint. Analytic expressions for the transmission and reflection coefficients of the coupler are obtained using a plane-wave theory and experimentally verified.(More)
Novel lattice-filter structures consisting of four-directional couplers are introduced, analyzed, and discussed. Four-directional couplers are discussed, and energy-conservation relations in a field-wave application are derived. A thick linear lattice filter is presented and studied as a simple extension to the traditional lattice. A two-dimensional lattice(More)
Optical lattice filter structures including gains are introduced and analyzed. The photonic realization of the active, adaptive lattice filter is described. The algorithms which map between gains space and filter coefficients space are presented and studied. The sensitivities of filter parameters with respect to gains are derived and calculated. An example(More)
Sensorimotor cortex plasticity induced by constraint-induced movement therapy (CIMT) in six children (10.2±2.1 years old) with hemiplegic cerebral palsy was assessed by functional near-infrared spectroscopy (fNIRS). The activation laterality index and time-to-peak/duration during a finger-tapping task and the resting-state functional connectivity were(More)
We present a simple method for multiplying the pulse repetition frequency of a given cw mode-locked laser. We report, in particular, the doubling and tripling of the c/2L frequency of a synchronously pumped mode-locked dye laser. This technique should prove useful for a variety of ultrashort pulse applications including high repetition rate optical pulse(More)
We designed, fabricated, and characterized a thermo-optically tunable compact (10 μm × 10 μm) silicon photonic crystal (PhC) light modulator that operates at around 1.55 µm for TE polarization. The operational principle of the device is the modulation of the cutoff frequency in a silicon-based line defect PhC. The cutoff frequency is shifted because of the(More)
An optically based rigid-body six-degrees of freedom (DOF) measurement system optimized for prospective (real-time) motion correction in magnetic resonance imaging (MRI) applications is described. By optimizing system capabilities to the specific applications requirements, the six-DOF measurement is accomplished using a single camera and simple three-disc(More)
A single CCD/DSP camera based optical system affords six degree of freedom motion tracking for MRI applications with resolutions in the range of < 50 microradians and 10-100 microns. The fiducial target is a lightweight compact three dimensional pattern that allows efficient, centroid based algorithms to determine distance translation and angle rotation at(More)