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The traditional Shack-Hartmann wavefront sensing (SHWS) system measures the wavefront slope by calculating the centroid shift between the sample and a reference piece, and then the wavefront is reconstructed by a suitable iterative reconstruction method. Because of the necessity of a reference, many issues are brought up, which limit the system in most(More)
In the traditional Shack-Hartmann wavefront sensing (SHWS) system, a lenslet array with a bigger configuration is desired to achieve a higher lateral resolution. However, practical implementation limits the configuration and this parameter is contradicted with the measurement range. We have proposed a digital scanning technique by making use of the high(More)
Humans rely on the feedbacks they received from a teacher in learning a new motor skill. Tactile feedback is effective in motor learning as it is direct and real-time. We proposed a 3D Orientation Guide (3DOG) which is made up of three coin-sized vibrating motors (tactors) to create meaningful tactile feedback to give users easily interpreted instruction on(More)
Freeform optical elements have wide applications in optics, manufacturing, and precision industries. Due to the diversity of the nonrotationally symmetrical nature of a surface profile, few noncontact measurement techniques have been proposed or reported. This paper proposes and develops a new reference-free beam-sampling (RFBS) methodology and system for(More)
Wavefront sensing systems measure the slope or curvature of a surface by calculating the centroid displacement of two focal spot images. Accurately finding the centroid of each focal spot determines the measurement results. This paper studied several widely used centroid-finding techniques and observed that thresholding is the most critical factor affecting(More)
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