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Development of a new microscope that looks deep into living tissue…

The Institute of Basic Science (IBS, President Doyoung Noh) announced on the 31st that the joint research team of Associate Director Choi Won-sik of the Center for Molecular Spectroscopy and Dynamics and Professor Lee Ye-ryeong of Konkuk University developed a microscope can image the deepest part of living tissue at high resolution among existing optical microscopes

When light passes through living tissue, two types of light are produced: direct light and diffused light. Direct light is light that travels straight through without being affected by biological tissue, and an image of an object is obtained using this light. Scattered light is light that is bent randomly in the direction of travel by cells or organelles in living tissue, and interferes with image acquisition.

Working principle of a stereoscopic reflection matrix microscope (Data = IBS)

When light penetrates deep into living tissue, scattered light becomes stronger compared to direct light and image information is blurred. Like fog, it becomes difficult to see inside living tissue. When passing through a scattering medium such as dense biological tissue, aberrations and chromatic dispersion occur, where the speed of propagation of straight light varies depending on the angle and wavelength, reducing the contrast or resolution of the image.

Current technologies have focused on restoring distorted images based on 2D information of a certain depth. However, there is a limit in that the direct light is depleted deep in the biological tissue and is difficult to restore.

The research team developed a ‘stereo reflection matrix microscope’ which improved imaging depth and resolution limits. First of all, by changing the wavelength and incident angle of the incident light, 3D information was collected from all the scattered light, and aberration and chromatic dispersion were correctly corrected. This made it possible to take high resolution images that cannot be realized with a general stereoscopic microscope.

Furthermore, two new algorithms were introduced to take advantage of the increased knowledge. The first algorithm is a technology that sequentially applies aberration data obtained from shallow depths where scattering is not severe to deep areas that were impossible to image with conventional techniques. By applying this algorithm, the effect of increasing the intensity of direct light by approximately 32 times was obtained.

Images taken with a stereoscopic reflection microscope. When a target image is obtained inside the scattering medium when increasing the spectral bandwidth from 15 nm to 225 nm, the matrix stereoreflection microscope (ae) shows a much clearer image than the current best planar microscope (gj) . In particular, in the 30 nm bandwidth, it can be seen that the conventional method (h) fails to restore the image, while the stereoscopic reflection matrix microscope (b) restores the image. Looking at the cross-section (k) of the image corresponding to the 105 nm bandwidth, it can be seen that the signal contrast of the stereoscopic reflection matrix microscope (blue) is much sharper. (Data = IBS)

The second algorithm is a technology that uses images from different depths at once. Through this, the amount of useful information increased, showing the effect of increasing the intensity of direct light by approximately 5.6 times. Strong direct light means you can observe more deeply.

Professor Lee Ye-ryeong said, “Not only can we get a clearer image than conventional technology, but we can also image objects at a depth that was impossible to image with conventional technology.” ” he said.

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Associate Research Director Choi Won-sik said, “Stereoscopic reflection matrix microscopy collects and uses the most extensive information about the interaction between light and medium among existing microscopy technologies. “We have reached an important milestone,” he said.

The results of the research were recently published in the journal Nature Communications.