Chemical micro-machining of complex 3-dimensional (3-D) patterns of silicon substrates was preliminarily explored by the confined etchant layer technique (CELT). Through systematic investigation, we demonstrated that cysteine as a scavenger and Br-2 as an etchant can be used to etch silicon substrates. The CELT has the potential to develop into a new means of micro-machining complex 3-D patterns on silicon substrates. However, due to the highly corrosive property of the chemicals used for the silicon etched system, great effort must be made to overcome these problems including the mold electrode with high chemical stability
RGB-D cameras (or color-depth cameras) play key roles in many vision applications. A typical RGB-D camera has only rough intrinsic and extrinsic calibrations that cannot provide the accuracy required in many vision applications. In this paper, we propose a novel and accurate sphere-based calibration framework for estimating the intrinsic and extrinsic parameters of color-depth sensor pair. Additionally, a method of depth error correction is suggested, and the principle of error correction is analyzed in detail. In our method, the feature extraction module can automatically and reliably detect the center and edges of the sphere projection, while excluding noise data and outliers, and the projection of the sphere center on RGB and depth images is used to obtain a closed solution of the initial parameters. Finally, all the parameters are accurately estimated within the framework of nonlinear global minimization. Compared to other state-of-the-art methods, our calibration method is easy to use and provides higher calibration accuracy. Detailed experimental analysis is performed to support our conclusions.
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