Electrical Engineering Department, University of California, Los Angeles, CA, 90095, USA.
Bioengineering Department, University of California, Los Angeles, CA, 90095, USA.
Sci Rep. 2016 Nov 30;6:37862. doi: 10.1038/srep37862.
High-resolution imaging of densely connected samples such as pathology slides using digital in-line holographic microscopy requires the acquisition of several holograms, e.g., at >6-8 different sample-to-sensor distances, to achieve robust phase recovery and coherent imaging of specimen. Reducing the number of these holographic measurements would normally result in reconstruction artifacts and loss of image quality, which would be detrimental especially for biomedical and diagnostics-related applications. Inspired by the fact that most natural images are sparse in some domain, here we introduce a sparsity-based phase reconstruction technique implemented in wavelet domain to achieve at least 2-fold reduction in the number of holographic measurements for coherent imaging of densely connected samples with minimal impact on the reconstructed image quality, quantified using a structural similarity index. We demonstrated the success of this approach by imaging Papanicolaou smears and breast cancer tissue slides over a large field-of-view of ~20 mm using 2 in-line holograms that are acquired at different sample-to-sensor distances and processed using sparsity-based multi-height phase recovery. This new phase recovery approach that makes use of sparsity can also be extended to other coherent imaging schemes, involving e.g., multiple illumination angles or wavelengths to increase the throughput and speed of coherent imaging.
使用数字线列全息显微镜对密集连接的样本（如病理载玻片）进行高分辨率成像需要获取多个全息图，例如在 >6-8 个不同的样本到传感器距离处，以实现稳健的相位恢复和对样本的相干成像。减少这些全息测量的数量通常会导致重建伪影和图像质量的损失，这对于生物医学和诊断相关的应用尤其不利。受大多数自然图像在某些域中是稀疏的这一事实的启发，我们在这里引入了一种基于稀疏性的相位重建技术，该技术在小波域中实现，以在对密集连接的样本进行相干成像时将全息测量的数量减少至少 2 倍，而对重建图像质量的影响最小，使用结构相似性指数进行量化。我们通过使用在不同样本到传感器距离处获取的 2 个线列全息图来对巴氏涂片和乳腺癌组织载玻片进行成像，证明了这种方法的成功，该载玻片具有约 20mm 的大视场，使用基于稀疏性的多高度相位恢复进行处理。这种利用稀疏性的新相位恢复方法还可以扩展到其他相干成像方案，例如涉及多个照明角度或波长，以提高相干成像的速度和速度。
