The non-uniformity of the readout circuit response in the infrared focal plane array unit detector can result in fixed pattern noise with stripe, which seriously affects the quality of the infrared images. Considering the problems of existing non-uniformity correction, such as the loss of image detail and edge blurring, a multi-scale residual network with attention mechanism is proposed for single infrared image stripe noise removal. A multi-scale feature representation module is designed to decompose the original image into varying scales to obtain more image information. The product of the direction structure similarity parameter and the Gaussian weighted Mahalanobis distance is used as the similarity metric; a channel spatial attention mechanism based on similarity (CSAS) ensures the extraction of a more discriminative channel and spatial feature. The method is employed to eliminate the stripe noise in the vertical and horizontal directions, respectively, while preserving the edge texture information of the image. The experimental results show that the proposed method outperforms four state-of-the-art methods by a large margin in terms of the qualitative and quantitative assessments. One hundred infrared images with different simulated noise intensities are applied to verify the performance of our method, and the result shows that the average peak signal-to-noise ratio and average structural similarity of the corrected image exceed 40.08 dB and 0.98, respectively.

The dynamic range of an X-ray digital imaging system is very important when detecting objects with a high absorption ratio. In this paper, a ray source filter is used to filter the low-energy ray components which have no penetrating power to the high absorptivity object to reduce the X-ray integral intensity. This enables the effective imaging of the high absorptivity objects and avoids the image saturation of low absorptivity objects, thus achieving single exposure imaging of high absorption ratio objects. However, this method will reduce the image contrast and weaken the image structure information. Therefore, this paper proposes a contrast enhancement method for X-ray images based on Retinex. Firstly, based on Retinex theory, the multi-scale residual decomposition network decomposes the image into an illumination component and a reflection component. Then, the contrast of the illumination component is enhanced through the U-Net model with the global–local attention mechanism, and the reflection component is enhanced in detail using the anisotropic diffused residual dense network. Finally, the enhanced illumination component and the reflected component are fused. The results show that the proposed method can effectively enhance the contrast in X-ray single exposure images of the high absorption ratio objects, and can fully display the structure information of images on devices with low dynamic range.

InGaAs photocathodes operating in the 0.9–1.7 μm spectral band are fundamentally limited by optical reflection losses and incomplete light absorption in thin active layers. In this work, we constructed periodic micro-nanostructured InGaAs photocathode models using finite-difference time-domain (FDTD) simulations, and systematically compared five micro-nanostructures (square pillars, circular pillars, square truncated pyramids, hexagonal prisms, and square pyramids) against a planar reference structure. At a wavelength of 1.55 μm, coupled scans of lateral dimension and height yielded maximum absorptance values of 0.749 for square pillars (0.6 μm side length, 0.9 μm height) and 0.682 for circular pillars (0.9 μm diameter, 0.9 μm height), corresponding to enhancements of 35.4% and 23.3%, respectively, relative to the planar reference. Circular pillars exhibited the lowest reflectance (0.072); however, their higher forward transmittance caused lower overall absorptance than that of square pillars. We then coupled the FDTD generation profiles to a steady-state drift-diffusion analysis of carrier collection. Under normalized illumination and a 5 V bias, the integrated generation increased by 29.2%. The modeled internal generation-rate-weighted collection efficiency η_C increased from 0.499 to 0.680, corresponding to a 36.2% enhancement, and the internally collected carrier-rate proxy increased by 76.1% relative to the planar reference. Under ideal fully-passivated side-wall conditions, the internally collected carrier-rate proxy increased by 76.1% relative to the planar reference. This study provides theoretical guidance for designing and optimizing high-performance micro/nanostructured InGaAs photocathodes.