A fiber-optic shape sensing based on 7-core fiber Bragg gratings (FBGs) is proposed and experimentally demonstrated. The investigations are presented for two-dimensional (2D) and three-dimensional (3D) shape reconstruction by distinguishing bending and twisting of 7-core optical fiber with FBGs. The curvature and bending orientation can be calculated by acquiring FBG wavelengths from any two side cores among the six outer cores. And the shape sensing in 3D space is computed by analytic geometry theory. The experiments corresponding of 2D and 3D shape sensing are demonstrated and conducted to verify the theoretical principles. The resolution of curvature is about 0.1 m^–1 for 2D measuring. The error of angle in shape reconstruction is about 1.89° for 3D measuring. The proposed sensing technique based on 7-core FBGs is promising of high feasibility, stability, and repeatability, especially for the distinguishing ability on the bending orientation due to the six symmetrical cores on the cross-section.

自动对焦可以快速、准确地将镜头调节到最佳位置，但目前该方式在算法和电路设计上还不够成熟，制约了它的应用。通过优化电路设计，选用TMS320VC5509A、FIFO和串口FLASH等低功耗、小尺寸封装芯片组成低功耗自动对焦电路，并基于Sobel算子的Tenengrad的改进图像边缘能量评价函数，采用可变窗口、合适的阈值，配合粗调（定步长）和精调(可变步长)搜索算法，设计实现了一种手持红外热像仪快速、准确地自动对焦的电路。实验结果表明，该方法高效可行，不仅能实现手持红外热像仪对目标的快速捕获，并能降低操作强度。

In this paper, the Raman spectrum signal de-noising based on stationary wavelet transform is discussed. Haar wavelet is selected to decompose the Raman spectrum signal for several levels based on stationary wavelet transform. The noise mean square {sigma}_j is estimated by the wavelet details at every level, and the wavelet details toward 0 by a threshold {sigma}_j (2\ln n)^{1/2} , where n is length of the detail, then recovery signal is reconstructed. Experimental results show this method not only suppresses noise effectively, but also preserves as many target characteristics of original signal as possible. This de-noising method offers a very attractive alternative to Raman spectrum signal noise suppress.