As the fundamental units of matter distribution in three-dimensional space, particles hold significant research value in the fields of medicine, environmental monitoring, combustion analysis, and aerospace research. However, detecting particles in scattering media often faces challenges such as low resolution and difficulties in localization. This study introduces a novel detection method based on autofocus compressed holography, which integrates compressed sensing and autofocus techniques to significantly enhance the axial resolution of reconstruction and the accuracy of particle detection. Through simulation and experimental validation, this method had demonstrated an axial resolution error of less than 3 μm, ensuring excellent detection precision. Experimental results further confirmed that, compared to traditional angular spectrum methods, this technology offered distinct advantages in observing the three-dimensional distribution of particles in scattering media and in assessing particle diameters. The research outcomes provide an innovative technical approach for scientific research and practical applications in the related fields.

In response to the challenges of eliminating the system noises from different viewing directions in a scanning ocular wavefront measurement system, this paper proposes a method to accurately locate the centroids of the spot array of Shack-Hartmann wavefront sensor and reconstruct the wavefront under high noise conditions. At first, the spot array images were globally processed using median filtering and mathematical morphology methods. Secondly, an improved maximum inter-class variance method was employed to determine the threshold for each sub-aperture. The Suzuki contour tracing algorithm was then utilized to identify the spot windows within which the centroids were computed. Finally, the proposed method combining the median area method precisely determined the centroid of the spots. A comparative analysis revealed that traditional methods failed to discriminate real spots under such high-noise conditions, whereas the proposed method could correctly identify them. The wavefront reconstruction errors, evaluated with PV and RMS values were less than 0.015λ and 0.001λ respectively, indicating that the accuracy and stability of the proposed method significantly outperformed traditional approaches.

The detection of ion concentration is of great significance in the fields of human health and environmental science. Compared with other ion detection methods, surface plasmon resonance (SPR) technology has the advantages of label-free detection, high sensitivity, and low detection limits, which brings new possibilities to the field of heavy metal ion monitoring. This article reviews the application and technical advances of SPR sensing technology in heavy metal ion detection. Firstly, this paper introduces the technical principles of SPR sensing. Then the paper focuses on the selection of sensing materials and surface modification, it emphasizes improvements in indicators such as sensitivity, linear dynamic range, specially for harmful heavy metal ions such as Pb2+ and Hg2+. Finally, the significant progress in terms of detection speed, sensitivity, etc. is introduced, and the development prospects of SPR technology is discussed.