Session Index

Label-free quantitative 3D phase imaging techniques are becoming increasingly important and popular in biological and medical applications for measurements and monitoring of cells, cell cultures and tissues. In particular, the possibility of the quantitative three-dimensional (3D) representation of living samples holds tremendous potential for advancing the field as it would provide unprecedented ease of insight into subtle intracellular mechanisms.

In this talk I will discuss the recent progress and trends in development and applications of 3D QPI systems based on optical diffraction tomography (ODT) with holographic projections. The presentation will focus on algorithms and systems which allow to overcome the most important issues such as: (i) lack of isotropic and sufficiently high spatial resolution essp. in the case of limited angle optical diffraction tomography(ODT), (ii) lack of the chemical specificity (general feature of QPI methods), (iii) multiple scattering which limits the size (thickness) of investigated samples (tissues, small scale objects) and (iv) lack of efficient solutions for in-vivo tissue investigations (such as in the case of optical coherence tomography (OCT)). The discussed solutions will include utilization of unified k-space theory of OCT which allows to provide an efficient use of combined OCT and ODT approaches, development of multimodal systems combining ODT with fluorescence microscopy and ODT with Raman spectroscopy, as well as applying AI solutions to support better reconstruction of biophysical parameters of cells and tissues.

However 3D QPI systems to be fully quantitative require proper metrological approach to assess the accuracy and precision of measurement. This problem is most often overlooked in both research and commercial QPI systems and there are no standardized methods for testing and reporting their metrological performance. Therefore I will also present the methodology for metrological evaluation of 3D QPI instruments for biomedical applications. The methodology entails suitable phantoms, quality assessment metric and easily reproducible protocol that is attainable for both numerical and experimental analysis. We demonstrate its applicability by comparing simulated and physical reconstructions obtained from 3 holographic tomography systems. The results will serve as a reference point for past and future research, encourage to benchmark new systems in a similar manner and further the efforts towards the standardization in 3D QPI metrology.

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Here, we propose a snapshot hyperspectral imaging system incorporated with the meta-optics concept and a small-data convex/deep (CODE) learning theory. Our hyperspectral imager contains only one single multi-wavelength metasurface chip, greatly reducing the physical size of device. To demonstrate the high performance of imaging system, a single-shot 4-band multispectral image is taken as the input. Consequently, a high-fidelity 18-band hyperspectral data cube is generated using the CODE-driven imaging system. We surmise that the metasurface-driven hyperspectral imaging combined with CODE small-data learning theory can pave a new way toward fundamental science studies and real-world applications with low-profile advanced instruments.

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Digital holographic microscopy (DHM) is a useful quantitative phase imaging
technique for observing transparent samples. In DHM, the diffraction grating is a widely used
component to implement the common-path configuration which helps stabilize the system and
reduce environmental fluctuations. However, the multiple unwanted higher-order diffraction
beams of grating lead to the system power loss. Here, we proposed using the volume
hologram (VH) to satisfy the common-path DHM configuration. By utilizing the single
diffraction order characteristics of the volume hologram, our proposed setup enhances system
stability while maintaining system power usage.

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We have developed a machine vision-based Automated Optical Inspection (AOI) system capable of automatically detecting defects in small electronic connectors and marking them for subsequent processing. This advancement serves to enhance the objectivity and accuracy of the inspection process.

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In this paper, we demonstrate the fabrication of the Geometric Phase (GP) optical device in an nematic liquid crystal cell (NLC cell) by using photo-alignment technique with poly[1- [4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt] azo-polymer (PAZO) as alignment layer. In experiments, GP grating optical element is fabricated and tested. The design principle, fabrication and characterization of GP devices are presented and discussed.

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For a periodic 64-channel optical phased array (OPA), we propose a novel approach combining the grouped phase error correction and beam steering with (n-1) stages and using 1D search algorithm with fixed and iterative weights. We leverage the power of parallel processing to reduce computation time significantly. The proposed method is 8-10 times faster while achieving results of 12.9-dB PSLL, 75% peak intensity with fixed weight, and 66% peak intensity, 15.68-dB PSLL for iterative weights.

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The efficacy and safety of traditional Chinese medicines highly depend on the quality of raw materials and process of preparation. Researchers have drawn attention to terahertz spectroscopy, using non-destructive method to conduct compositional analysis of Chinese medicines through their fingerprint spectra. Due to varied experimental conditions and data processing models adopted by different labs, integrated THz spectral database have yet to be available, nor does the standard operational procedure. Herein, we focus on the establishment of a systematized procedure for THz-based material analysis, such technique can provide powerful and time-effective quality monitoring of various Chinese herbs and medicines.

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