Anand Vijayakumar, Ng Soon Hock, Katkus Tomas, Juodkazis Saulius
Opt Express. 2021 May 10;29(10):15551-15563. doi: 10.1364/OE.426021.
Coded aperture imaging (CAI) technology is a rapidly evolving indirect imaging method with extraordinary potential. In recent years, CAI based on chaotic optical waves have been shown to exhibit multidimensional, multispectral, and multimodal imaging capabilities with a signal to noise ratio approaching the range of lens based direct imagers. However, most of the earlier studies used only narrow band illumination. In this study, CAI based on chaotic optical waves is investigated for white light illumination. A numerical study was carried out using scalar diffraction formulation and correlation optics and the lateral and axial resolving power for different spectral width were compared. A binary diffractive quasi-random lens was fabricated using electron beam lithography and the lateral and axial point spread holograms are recorded for white light. Three-dimensional imaging was demonstrated using thick objects consisting of two planes. An integrated sequence of signal processing tools such as non-linear filter, low-pass filter, median filter and correlation filter were applied to reconstruct images with an improved signal to noise ratio. A denoising deep learning neural network (DLNN) was trained using synthetic noisy images generated by the convolution of recorded point spread functions with the virtual object functions under a wide range of aberrations and noises. The trained DLNN was found to reduce further the reconstruction noises.
编码孔径成像（CAI）技术是一种快速发展的间接成像方法，具有巨大的潜力。近年来，基于混沌光波的CAI已被证明具有多维、多光谱和多模态成像能力，其信噪比接近基于透镜的直接成像仪的范围。然而，大多数早期研究仅使用窄带照明。在本研究中，对基于混沌光波的CAI进行了白光照明研究。使用标量衍射公式和相关光学进行了数值研究，并比较了不同光谱宽度的横向和轴向分辨率。使用电子束光刻制作了二元衍射准随机透镜，并记录了白光的横向和轴向点扩散全息图。使用由两个平面组成的厚物体进行了三维成像演示。应用了诸如非线性滤波器、低通滤波器、中值滤波器和相关滤波器等一系列信号处理工具来重建具有改善信噪比的图像。使用在广泛的像差和噪声下由记录的点扩散函数与虚拟物体函数卷积生成的合成噪声图像训练了一个去噪深度学习神经网络（DLNN）。发现训练后的DLNN进一步降低了重建噪声。
