Optical resolution photoacoustic microscopy (ORPAM) is important for various biomedical applications, such as the study of cellular structures, microcirculation systems, and tumor angiogenesis. However, the lateral resolution of a conventional ORPAM is limited by optical diffraction. In this work, we report a simulation study to achieve subdiffraction-limited super-resolution in ORPAM using microspheres. Laser radiation is focused through a microsphere to generate a photonic nanojet, which provides the possibility to break the diffraction limit in ORPAM by reducing the size of the excitation volume. In our simulations using microspheres, we observed improvement in the lateral resolution up to compared to conventional ORPAM. The method is simple, cost effective, and can provide far-field resolution. This approach may provide new opportunities for many biomedical imaging applications that require finer resolution.

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A simple approach to fabricate sticky superhydrophobic polystyrene surfaces,We present a facile method for the fabrication of a sticky superhydrophobic polystyrene surface using ethanol as the non-solvent. The obtained surface shows the hierarchical textured morphology as well as the multiple scales of roughness and large numbers of microspheres. Without any chemical modification, the prepared polystyrene surface exhibits sticky superhydrophobicity with a high equilibrium contact angle of 153°. Interestingly, a water droplet on the surface cannot move at any tilt angle even when the substrate is turned upside down. The mechanism of the fabricated surface with high adhesion is discussed in detail. Moreover, the obtained polystyrene surface exhibits the strong adhesion to the liquid droplets of pH value from 1 to 14.

In this paper, a new image fusion algorithm based on non-subsampled contourlet transform (NSCT) is proposed for the fusion of multi-focus images. The selection of different subband coefficients obtained by the NSCT decomposition is critical to image fusion. So, in this paper, firstly, original images are decomposed into different frequency subband coefficients by NSCT. Secondly, the selection of the low-frequency subband coefficients and the bandpass directional subband coefficients is discussed in detail. For the selection of the low-frequency subband coefficients, the non-negative matrix factorization (NMF) method is adopted. For the selection of bandpass directional subband coefficients, a regional cross-gradient method that selects the coefficients according to the minimum of the regional cross-gradient is proposed. Finally, the fused image is obtained by performing the inverse NSCT on the combined coefficients. The experimental results show that the proposed fusion algorithm can achieve significant results in getting a new image where all parts are sharp.

The nonsubsampled contourlet transform (NSCT) is a new multi-resolution transform, which can give an asymptotic representation of edges and contours in image by virtue of its characteristics of multi-direction, flexible multi-scale and shift-invariant simultaneity. For fusion between visible light image and infrared image, this paper proposed a new method based on nonsubsampled contourlet transform and the visual characteristics of region. Firstly, two original images were decomposed into different frequency sub-band coefficients by using NSCT, and then the selection of the low frequency subband coefficient and the bandpass direction subband coefficient was discussed respectively. For the choice of low frequency subband coefficient, this paper proposed a new method that chose coefficient based on the visual characteristics of region and gradient characteristics. For the choice of bandpass direction subband coefficient, this paper uses a direct method that chose the coefficient based on maximum regional uniformity obtained by the visual characteristics of region. Finally, the fused image was obtained by performing the inverse NSCT on the combined coefficients. The experimental results show that this fusion algorithm proposed in this paper achieved significant results to extract target in the infrared image and preserve edge of the target. At the same time, it also achieved good results to effectively preserve image details in the visible light image.