Changgeng (bRUCE) lIU, pH.d.

Research Description:

My current research interest mainly focuses on two aspects:

• Optical imaging theory and technologies, including digital holography, confocal microscopy, adaptive optics, optical coherence tomography, super-resolution microscopy, interferometry, and diffraction imaging.
• Biomedical optics and imaging, including cellular imaging, retinal imaging, retinal physiology, eye tracking, and oculomotor.

Some of my past research projects include:

1. Develop wide-field digital holographic imaging techniques to investigate biological samples without a need of staining and industrial samples both at nanometer precision. Also, investigate the mathematical principles, novel computational algorithms and computer simulation techniques to automate the digital holographic imaging system for practical applications.
2. Develop digital adaptive optics ophthalmoscopes and microscopes to eliminate optical aberration and improve the image resolution and contrast without complex hardware pieces such as wave front sensor and deformable mirror, which are highly costly and hard to operate. Digital adaptive optics can replace these hardware by numerical processing, leading to compact, cost-effective, and high- resolution ophthalmoscopes and microscopes for clinical use and biomedical research.
3. Invent and develop high speed digital confocal holographic imaging technologies to push the frontier of digital holographic imaging technologies into scattering tissue imaging with enhanced sensitivity, optical sectioning and an ability of imaging transparent layer in the tissue. These technologies have the potential of imaging transparent neuronal cells in the human retina and other tissues without staining, enabling effective screening and monitoring of neuron related retina diseases such as glaucoma, which is one of leading causes of vision impair or even legal blindness.
4. Develop multimodal biomedical imaging by use of novel light sources, whose spatial coherence can be tailored for different imaging needs. Low spatial coherence is used to image the structure of the tissue while high spatial coherence is utilized to quantify blood flow dynamics.

Selected Publications:

1. C. Liu, D. Thapa, X. Yao, "Digital Adaptive Optics Confocal Microscopy Based on Iterative Retrieval of Optical Aberration from a Guidestar Hologram," Optics Express 25 (7), 8223-8236 (2017).
2. C. Liu, H. Cao, M. Choma, "Coherent Artifact Suppression in Line-field Reflection Confocal Microscopy Using a Low Spatial Coherence Light Source," Optics Letters 41 (20), 4775-4778 (2016).
3. C. Liu, S. Knitter, Z. Cong, I. Sencan, H. Cao, M. A. Choma, "High-speed Line-field Confocal Holographic Microscope for Quantitative Phase Imaging," Optics Express 24 (9), 9251-9265 (2016).
4. C. Liu, M. K. Kim, "Digital Adaptive Optics Line-Scanning Confocal Imaging System," Journal of Biomedical Optics 20 (11), 8223-8236 (2015).
5. C. Liu, S. Marchesini, M. K. Kim, "Quantitative Phase-Contrast Confocal Microscope," Optics Express 22 (15), 17830-17839 (2014).
6. C. Liu, X. Yu, M. K. Kim, "Phase Aberration Correction by Correlation in Digital Holographic Adaptive Optics," Applied Optics 52 (12), 2940-2949 (2013).
7. C. Liu, X. Yu, M. K. Kim, "Fourier Transform Digital Holographic Adaptive Optics Imaging System," Applied Optics 51 (35), 8449-8454 (2012).
8. C. Liu, M. K. Kim, "Digital Holographic Adaptive Optics for Ocular Imaging: Proof of Principle," Optics Letters 36 (14), 2710-2712 (2011).
9. C. Liu, D. Wang, J. J. Healy, B. M. Hennelly, J. T. Sheridan, M. K. Kim, "Digital Computation of the Complex Linear Canonical Transform," Journal of the Optical Society of America A 28 (7), 1379-1386 (2011).
10. C. Liu, D. Wang, Y. Zhang, "Comparison and Verification of Numerical Reconstruction Methods in Digital Holography," Optical Engineering 48 (10), 105802 (2009).