Dongkyun Kang
Assistant Professor, BIO5 Institute
Assistant Professor, Biomedical Engineering
Assistant Professor, Optical Sciences
Primary Department
(520) 621-6997
Work Summary
We are developing low-cost in vivo microscopy devices that can visualize cellular details of human tissues in vivo and help disease diagnosis and treatment in low-resource settings, high-speed tissue microscopy technologies that can examine entire organ under risk of having malignant diseases and detect small, early-stage lesions, and miniature microscopy devices that have the potential to examine anatomically-challenging human organs and facilitate integration of microscopic imaging with other imaging modalities.
Research Interest
My research is focused on developing novel optical microscopy technologies and improving patient care using these technologies. My research area includes (1) low-cost smartphone in vivo microscopy, (2) high-speed comprehensive in vivo endomicroscopy, and (3) ultraminiature endomicroscopy. (1) Low-cost smartphone in vivo microscopy: I am currently leading a NIH-sponsored research project for developing smartphone confocal microscope and diagnosing Kaposi's sarcoma in Uganda with the smartphone confocal microscope. I will further advance the smartphone microscopy technology and address other applications, including diagnosis of cervical and oral cancers in low-resource settings, large-population screening of skin cancers in the US, and aiding science and medical educations. (2) High-speed comprehensive in vivo endomicroscopy: I have previously developed a high-speed confocal microscopy system and endoscopic imaging catheters and acquired largest in vivo confocal images of human organ reported. At the UA, I plan to further advance the technology by i) increasing the imaging speed by orders of magnitude and ii) incorporating fluorescence imaging modality. (3) Ultraminiature endomicroscopy: In my previous research, I have developed miniature endoscopic catheters that can visualize internal organs in vivo through a needle-sized device. At the UA, I will develop microscopic imaging catheter with a extremely small diameter and utilize it for guiding cancer diagnosis and treatment.


Kang, D., & Gweon, D. (2005). Two-dimensional imaging theory of confocal self-interference microscopy. Journal of the Optical Society of America. A, Optics, image science, and vision, 22(12), 2737-45.

A two-dimensional coherent imaging equation is derived for confocal self-interference microscopy (CSIM), which uses a birefringent material to generate an interference pattern in the detection optics. This interference pattern, called a self-interference pattern, sharpens the point-spread function (PSF) along the lateral direction. To derive the imaging equation, an equation for the self-interference pattern is derived. Numerical simulation results based on the imaging equation are presented. One-point response results show a 42.8% reduction in the FWHM of the lateral PSF. Two-point response results show a nearly twofold improvement in two-point resolution.

Kang, D., Yoo, H., Jillella, P., Bouma, B. E., & Tearney, G. J. (2011). Comprehensive volumetric confocal microscopy with adaptive focusing. Biomedical optics express, 2(6), 1412-22.

Comprehensive microscopy of distal esophagus could greatly improve the screening and surveillance of esophageal diseases such as Barrett's esophagus by providing histomorphologic information over the entire region at risk. Spectrally encoded confocal microscopy (SECM) is a high-speed reflectance confocal microscopy technology that can be configured to image the entire distal esophagus by helically scanning the beam using optics within a balloon-centering probe. It is challenging to image the human esophagus in vivo with balloon-based SECM, however, because patient motion and anatomic tissue surface irregularities decenter the optics, making it difficult to keep the focus at a predetermined location within the tissue as the beam is scanned. In this paper, we present a SECM probe equipped with an adaptive focusing mechanism that can compensate for tissue surface irregularity and dynamic focal variation. A tilted arrangement of the objective lens is employed in the SECM probe to provide feedback signals to an adaptive focusing mechanism. The tilted configuration also allows the probe to obtain reflectance confocal data from multiple depth levels, enabling the acquisition of three-dimensional volumetric data during a single scan of the probe. A tissue phantom with a surface area of 12.6 cm(2) was imaged using the new SECM probe, and 8 large-area reflectance confocal microscopy images were acquired over the depth range of 56 μm in 20 minutes. Large-area SECM images of excised swine small intestine tissue were also acquired, enabling the visualization of villous architecture, epithelium, and lamina propria. The adaptive focusing mechanism was demonstrated to enable acquisition of in-focus images even when the probe was not centered and the tissue surface was irregular.

Tearney, G. J., & Kang, D. (2017). Introduction to biomedical optical imaging. Lasers in surgery and medicine, 49(3), 214.
Kim, J., Kang, D., & Gweon, D. (2006). Spectrally encoded slit confocal microscopy. Optics letters, 31(11), 1687-9.

A simple and cost-effective method for real-time imaging in confocal microscopy is proposed. Spectrally encoded slit confocal microscopy (SESCoM) uses a spectral encoding technique together with a confocal slit aperture to achieve two-dimensional images. Simulation and experimental results of the SESCoM's axial and lateral performances are presented. The measured FWHM of the axial response is 1.15 mum when an objective with a NA of 0.95 is used. FWHMs of the lateral line spread functions are measured to be 236 and 244 nm along the x and y directions, respectively. Both the axial and the lateral experimental results agree well with the simulation results.

Kang, D., & Gweon, D. (2005). Image of a straight edge in confocal self-interference microscopy. Optics letters, 30(13), 1650-2.

An image of a straight edge in confocal self-interference microscopy (CSIM) is analyzed. Simulations of edge images based on a two-dimensional imaging equation are presented that show a 103% increase in edge gradient and a 43.1% decrease in the 10-90% width. The first experimental results, to our knowledge, for CSIM are presented and show good agreement with the simulation results and a 23% decrease in the 10-90% width.