RESEARCH

This study introduces a polarization phase microscope that combines polarization filters with a phase microscope using digital holography. It enables the measurement and visualization of the polarization response of a sample. The measured responses are converted into a spatially resolved Jones matrix, capturing complete polarization information. By applying optical tomographic imaging, we develop an algorithm to map polarization responses to 3D space. Our goal is to construct a functional microscope system that selectively images birefringence distribution in living cells and tissues, revealing optical anisotropy inaccessible to conventional microscopes.

K. Park, et al., ACS Photonics 8, 3042 (2021)

T. D. Yang et al., Opt. Express 24, 29302 (2016)

T. D. Yang et al., Opt. Express 24, 9480 (2016)

In this study, we present a reflection phase microscope that offers high resolution, improved sensitivity, and wide-field imaging capabilities. This microscope enables the acquisition of 3D images showcasing detailed structures within living cells. Moreover, it allows for the observation of nanometer-scale cellular motions associated with rapid membrane fluctuations. Our aim is to quantitatively measure the fast and precise kinetics of living cells, aiding in predicting cellular conditions during disease development and facilitating the development of diagnostic protocols through cell observation. Through our efforts, we demonstrate the vast potential of this method for various biological applications.

Y. G. Kang et al., Opt. Express 31, 44741 (2023)

M. G. Hyeon et al., Sci. Rep. 11, 22774 (2021)

M. G. Hyeon et al., ACS Photonics 6, 757 (2019)

Y. Choi et al., Optica 5, 1468 (2018)

Our research focuses on the development of ultra-thin endoscopes, available in both rigid and flexible types. For rigid endoscopes, we utilize Graded-Index (GRIN) lenses due to their exceptional thinness and length without compromising imaging capability. We address image aberrations through post-processing techniques, effectively mitigating their impact. This approach enables the achievement of high-resolution, wide-field endoscopic imaging using a long and thin GRIN probe.

In the case of flexible endoscopes, which are more practical for real-world applications, we employ an optical fiber bundle as the imaging probe. Fiber bundles are commonly used for their flexibility in transmitting images. However, their pixelated nature limits high-resolution imaging. To overcome this limitation, we have incorporated digital holography into fiber bundle imaging and developed a unique image processing algorithm capable of handling image distortion caused by the core fibers. By capturing both amplitude and phase information within the fiber bundle images, we can effectively remove pixelated artifacts, thus enabling the implementation of a high-resolution endomicroscope using a fiber bundle with a diameter as small as 500 microns or even smaller.

T. V. A. Nguyen et al., ACS Photonics 11, 385 (2024) 

M. Kang et al., Opt. Express 31, 11705 (2023)

W. Choi et al., Nat. Commun. 13, 4469 (2022)

M. Kang et al., Opt. Express 29, 34360 (2021)

K. Park et al., Biomed. Opt. Express 11, 4976 (2020)

C. Yoon et al., Sci. Rep. 7, 6524 (2017)

We are currently developing a cutting-edge technology that utilizes an ultra-thin bundle of optical fibers with needles attached to their end facets. This innovative approach involves inserting the needles directly into the tissue, enabling the transmission of a laser beam to the targeted lesion through the optical fibers, bypassing the skin. By doing so, we can overcome the challenges associated with scattering and thermal damage caused by laser absorption in the skin. This method allows for the use of lower light intensity, minimizing the risk of unnecessary injury. Consequently, photothermal therapy (PTT) on cancer tissues can be performed with significantly enhanced efficiency.

Additionally, our research extends beyond cancer treatment, as we explore diverse applications for this technology. We are particularly interested in leveraging its capabilities for observing cell dynamics with remarkable sensitivity of approximately 10 nanometers and achieving high-accuracy aberration correction. These advancements hold promising prospects for a wide range of applications beyond cancer therapy.

N. Im et al., Journal of Advanced Research, 31 155 (2021)

T. D. Yang et al., Biomed. Opt. Express 8, 3482 (2017)

K. Park, et al., Opt. Express 29, 41894 (2021)

K. Park, et al., Sci. Rep. 9, 1206 (2019)