Optics express
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In this paper we investigate the optical forces induced by localized optical modes propagating along three parallel waveguides, of which only the central one is free to move. In this configuration, when all three waveguides are identical, the components of the optical-force acting on the free beam are decoupled along the axis of symmetry. ⋯ We also study non symmetric configurations, that can be used, for example, to tailor the position of the optical trap. Unlike other techniques that rely on buckling, multi-mode excitation or radiation-pressure, single-mode optomechanical-operation should help the realization of faster and simpler on-chip positioning of a single nanobeam since most of the parameters involved can be controlled with great precision.
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This paper presents a new high-resolution computational integral imaging system employing a pickup with the axial movement of a lenslet array and a computation reconstruction algorithm with pixel-to-pixel mapping. In the proposed method, a lenslet array and its image sensor are moved together along the z-axis direction (or axial direction) and a series of elemental image arrays are obtained while moving. ⋯ To show the usefulness of the proposed method, experiments are conducted. The results indicate that the proposed method is superior to the existing method such as MALT in terms of image quality.
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We present a theoretical method for analyzing the first-order optics of stabilized zoom lenses with two focal-length-variable elements. The zoom equations are established through the use of the Gaussian brackets method. This is done because the optical power of the focal-length-variable elements varies during the zooming process. ⋯ This process leads to an increase in the zoom ratio of the zoom system. The results show successful four-group stabilized zoom lens designs with 2:1 and 5:1 zoom ratios, using two deformable mirrors as focal-length-variable elements. This system, with the inherent characteristics of a steepest gradient, could miniaturize zoom systems.
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Being the closest layer to our body, textiles provide an ideal platform for integrating sensors and actuators to monitor physiological signals. We used a woven textile to integrate photodiodes and light emitting diodes. LEDs and photodiodes enable near-infrared spectroscopy (NIRS) systems to monitor arterial oxygen saturation and oxygenated and deoxygenated hemoglobin in human tissue. ⋯ The sensor textile is applied to measure the pulse waves in the fingertip and the changes in oxygenated and deoxygenated hemoglobin during a venous occlusion at the calf. The system has a signal-to-noise ratio of more than 70 dB and a system drift of 0.37% ± 0.48%. The presented work demonstrates the feasibility of integrating photodiodes and LEDs into woven textiles, a step towards wearable health monitoring devices.
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Adaptive optics (AO) ophthalmoscopes with small fields of view have limited clinical utility. We propose to address this problem in reflective instruments by incorporating a viewfinder pupil relay designed by considering pupil and image centering and conjugation. ⋯ Two different methods for calculating the focal length and orientation of the concave mirrors in the afocal viewfinder relay are introduced. Finally, a 2.2 × viewfinder mode is demonstrated in an AO scanning light ophthalmoscope.