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168 results on '"Chu, Kaiqin"'

15. Fast Raman imaging through the combination of context-aware matrix completion and low spectral resolution.

Author

Jiang, Ziling, Wang, Xianli, Chu, Kaiqin, and Smith, Zachary J.

Subjects
IMAGE reconstruction algorithms, RAMAN spectroscopy, SIGNAL-to-noise ratio
Abstract

Raman hyperspectral imaging is an effective method for label-free imaging with chemical specificity, yet the weak signals and correspondingly long integration times have hindered its wide adoption as a routine analytical method. Recently, low resolution Raman imaging has been proposed to improve the spectral signal-to-noise ratio, which significantly improves the speed of Raman imaging. In this paper, low resolution Raman spectroscopy is combined with "context-aware" matrix completion, where regions of the sample that are not of interest are skipped, and the regions that are measured are under-sampled, then reconstructed with a low-rank constraint. Both simulations and experiment show that low-resolution Raman boosts the speed and image quality of the computationally-reconstructed Raman images, allowing deeper sub-sampling, reduced exposure time, and an overall >10-fold improvement in imaging speed, without sacrificing chemical specificity or spatial image quality. As the method utilizes traditional point-scan imaging, it retains full confocality and is "backwards-compatible" with pre-existing traditional Raman instruments, broadening the potential scope of Raman imaging applications. [ABSTRACT FROM AUTHOR]

Published
2023
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28. Incoherently combining logarithmic aspheric lenses for extended depth of field

Author

Chu, Kaiqin, George, Nicholas, and Chi, Wanli

Subjects
Aspherical lenses -- Usage, Aspherical lenses -- Methods, Depth of field (Photography) -- Methods, Astronomy, Physics
Abstract

We describe a method for combining concentric logarithmic aspheric lenses in order to obtain an extended depth of field. Substantial improvement in extending the depth of field is obtained by carefully controlling the optical path difference among the concentric lenses so that their outputs combine incoherently. The system is analyzed through diffraction theory and the point spread function is shown to be highly invariant over a long range of object distances. After testing the image performance on a three-dimensional scene, we found that the incoherently combined logarithmic aspheres can provide a high-quality image over an axial distance corresponding to a defocus of [+ or -]14 ([lambda]/4). Studies of the images of two-point objects are presented to illustrate the resolution of these lenses. OCIS codes: 110.5220, 220.1000, 260.1960, 100.1830, 350.4600, 030.1670.

Published
2009

31. Extending the depth of field through unbalanced optical path difference

Author

Chu, Kaiqin, George, Nicholas, and Chi, Wanli

Subjects
Depth of field (Photography) -- Research, Diffraction -- Research, Stochastic processes -- Research, Astronomy, Physics
Abstract

We describe a simple method to extend the depth of field of a conventional camera by inserting a transparent annular ring in front of the pupil of the lens. The insertion of the ring creates an unbalanced optical path difference across the lens aperture, which partitions the pupil and leads to an extended depth of field. This system is analyzed by diffraction and random process theory. Experiments are reported that are in good agreement with the theory. OCIS codes: 030.0030, 100.0100, 110.0110, 120.0120, 130.0130, 220.0220.

Published
2008

36. Epi‐illumination dark‐field microscopy enables direct visualization of unlabeled small organisms with high spatial and temporal resolution.

Author

Shi, Ruijie, Chen, Xiangyang, Huo, Jing, Guo, Siyue, Smith, Zachary J., and Chu, Kaiqin

Abstract

Dark‐field microscopy is known to offer both high resolution and direct visualization of thin samples. However, its performance and optimization on thick samples is under‐explored and so far, only meso‐scale information from whole organisms has been demonstrated. In this work, we carefully investigate the difference between trans‐ and epi‐illumination configurations. Our findings suggest that the epi‐illumination configuration is superior in both contrast and fidelity compared to trans‐illumination, while having the added advantage of experimental simplicity and an "open top" for experimental intervention. Guided by the theoretical analysis, we constructed an epi‐illumination dark‐field microscope with measured lateral and axial resolutions of 260 nm and 520 nm, respectively. Subcellular structures in whole organisms were directly visualized without the need for image reconstruction, and further confirmed via simultaneous fluorescence imaging. With an imaging speed of 20 to 50 fps, we visualize fast dynamic processes such as cell division and pharyngeal pumping in Caenorhabditis elegans. [ABSTRACT FROM AUTHOR]

Published
2022
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43. Fast confocal Raman imaging via context-aware compressive sensing.

Author

Hu, Chuanzhen, Wang, Xianli, Liu, Ling, Fu, Chuanhai, Chu, Kaiqin, and Smith, Zachary J.

Subjects
IMAGING systems in chemistry, RAMAN scattering, BIOCHEMICAL models, ACQUISITION of data
Abstract

Raman hyperspectral imaging is a powerful method to obtain detailed chemical information about a wide variety of organic and inorganic samples noninvasively and without labels. However, due to the weak, nonresonant nature of spontaneous Raman scattering, acquiring a Raman imaging dataset is time-consuming and inefficient. In this paper we utilize a compressive imaging strategy coupled with a context-aware image prior to improve Raman imaging speed by 5- to 10-fold compared to classic point-scanning Raman imaging, while maintaining the traditional benefits of point scanning imaging, such as isotropic resolution and confocality. With faster data acquisition, large datasets can be acquired in reasonable timescales, leading to more reliable downstream analysis. On standard samples, context-aware Raman compressive imaging (CARCI) was able to reduce the number of measurements by ∼85% while maintaining high image quality (SSIM >0.85). Using CARCI, we obtained a large dataset of chemical images of fission yeast cells, showing that by collecting 5-fold more cells in a given experiment time, we were able to get more accurate chemical images, identification of rare cells, and improved biochemical modeling. For example, applying VCA to nearly 100 cells' data together, cellular organelles were resolved that were not faithfully reconstructed by a single cell's dataset. [ABSTRACT FROM AUTHOR]

Published
2021
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