High accuracy and time resolution optical transfer delay (OTD) measurement is highly desired in many multi-path applications, such as optical true-time-delay-based array systems and distributed optical sensors. However, the time resolution is usually limited by the frequency range of the probe signal in frequency-multiplexed OTD measurement techniques. Here, we proposed a time-resolution enhanced OTD measurement method based on incoherent optical frequency domain reflectometry (I-OFDR), where an adaptive filter is designed to suppress the spectral leakage from other paths to break the resolution limitation. A weighted least square (WLS) cost function is first established, and then an iteration approach is used to minimize the cost function. Finally, the appropriate filter parameter is obtained according to the convergence results. In a proof-of-concept experiment, the time-domain response of two optical links with a length difference of 900 ps is successfully estimated by applying a probe signal with a bandwidth of 400 MHz. The time resolution is improved by 2.78 times compared to the theoretical resolution limit of the inverse discrete Fourier transform (iDFT) algorithm. In addition, the OTD measurement error is below ±0.8ps. The proposed algorithm provides a novel way to improve the measurement resolution without applying a probe signal with a large bandwidth, avoiding measurement errors induced by the dispersion effect.

Structured illumination microscopy (SIM) has been widely applied in the superresolution imaging of subcellular dynamics in live cells. Higher spatial resolution is expected for the observation of finer structures. However, further increasing spatial resolution in SIM under the condition of strong background and noise levels remains challenging. Here, we report a method to achieve deep resolution enhancement of SIM by combining an untrained neural network with an alternating direction method of multipliers (ADMM) framework, i.e., ADMM-DRE-SIM. By exploiting the implicit image priors in the neural network and the Hessian prior in the ADMM framework associated with the optical transfer model of SIM, ADMM-DRE-SIM can further realize the spatial frequency extension without the requirement of training datasets. Moreover, an image degradation model containing the convolution with equivalent point spread function of SIM and additional background map is utilized to suppress the strong background while keeping the structure fidelity. Experimental results by imaging tubulins and actins show that ADMM-DRE-SIM can obtain the resolution enhancement by a factor of ∼1.6 compared to conventional SIM, evidencing the promising applications of ADMM-DRE-SIM in superresolution biomedical imaging.

随着3D显示被应用到**医疗等尖端领域，高分辨率的3D图像变得尤为重要。然而，集成成像的3D显示性能受制于2D显示屏的分辨率。为了突破2D显示屏的分辨率限制，本文提出了基于回返器和反射偏振片的集成成像3D显示装置。该装置将显示器上的微图像阵列（elemental image array，EIA）通过反射型偏振片分离成偏振方向正交的两束光线，回返器、四分之一波片和反射型偏振片分别将两束偏振光反射，并沿着像素的对角线方向以2/2个像素错位叠加，形成一个具有更小像素单元和更多像素数量的高分辨率EIA。根据两个偏振EIA和叠加的高分辨率EIA之间的像素索引关系，反向计算出偏振EIA的像素值。实验结果表明，该系统不仅可以重构出高分辨率的3D图像，还减弱了像素间的黑网格。