利用图像传感器的成像灰度实现位移测量，需要在位移过程中用相机对靶标进行成像，进而建立位移值与成像灰度值之间的映射关系，即成像灰度模型，该方法的测量精度取决于成像灰度模型与灰度噪声水平。实际测量过程中，光照不均匀、靶标制造误差、相机成像系统畸变等外部误差源以及内部不同图像传感器单元之间成像特性的差异性均会使成像灰度模型偏离理想情况，从而影响测量结果。为了进一步提高测量精度，所提方法考虑了上述的非线性因素带来的建模误差，采用Fourier级数与高阶多项式结合构造成像灰度模型类，提高模型的泛化逼近能力进而提高建模精度，校正上述误差源导致的灰度畸变。在此基础上，采用基于位移连续性原理的顺序求解法解算位移，实验结果显示，使用该改进模型在10.46 mm行程下的位移测量误差标准差由校正前的56.4 μm降低至1.5 μm。

Direct current pulsed discharge is a promising route for producing high-density metastable particles required for optically pumped rare gas lasers (OPRGLs). Such metastable densities are easily realized in small discharge volumes at near atmospheric pressures, but problems appear when one is trying to achieve a large volume of plasma for high-power output. In this work, we examined the volume scalability of high-density metastable argon atoms by segmented discharge configuration. Two discharge zones attached with peaking capacitors were connected parallelly by thin wires, through which the peaking capacitors were charged and of which the inductance functioned as ballasting impendence to prevent discharging in only one zone. A uniform and dense plasma with the peak value of the number densities of Ar (1s⁵) on the order of 1013cm-3 was readily achieved. The results demonstrated the feasibility of using segmented discharge for OPRGL development.

Photoacoustic imaging (PAI) has been used to characterize the spatial and quantitative features of lipid-rich atherosclerotic plaques with high sensitivity and specificity. In this Letter, we first validate that the ultra-low temperature and formaldehyde treatment have no effect on photoacoustic characteristics of the artery samples. Comparative experiments between the PAI and histological results demonstrate that the ultra-low temperature or formaldehyde treatment has few effects on the PAI of the lipid-rich atherosclerotic plaques; the lipid relative concentration and the lipid percentage by PAI hold high correlation with histology.