MyoungKi Ahn

Cross structured illumination for high speed high resolution line scanning confocal microscopy

Previous research presented the structured illumination confocal scanning microscope (SICSM) so as to improve the lateral resolution of the confocal microscope. However, the image acquisition speed of the SICSM is very slow and also an alignment error due to the mechanical rotation of a grating and a slit can easily occur. As a theoretical study, in this paper we propose a new SI method, the cross SI method, which improves lateral resolution and image acquisition speed. Performances of the conventional SI and the proposed SI methods are compared by analysis of the modulation transfer function. The proposed SI method shows similar lateral resolution and can shorten the image acquisition time compared to the conventional SI method. The cross structured illumination confocal microscope (CSICM) is combined with the cross SI pattern optics and the line scanning confocal microscope. We have introduced a 2-D diffractive grating, four linear polarizers and four cylindrical lenses in order to create the cross SI pattern. The effects of the cross SI pattern, intensity and visibility, on the system performance are analyzed. The CSICM has double the lateral resolution of the conventional microscope, an optical sectioning ability and a fast image acquisition speed.

Polarization-sensitive spectral-domain optical coherence tomography using a multi-line single camera spectrometer

We describe a polarization sensitive spectral domain optical coherence tomography technique based on a single camera spectrometer that includes a multiplexed custom grating, camera lenses, and a high-speed three-line CCD camera. Two orthogonally polarized beams could be separately taken by two lines of the camera as a result of vertically different incident angles. The system could provide the imaging capabilities of a full camera speed and increased measurable depth. The proposed optical coherence tomography system could make a distinction between the normal muscle and cancerous tissue from the chest of a DSred GFP mouse and the OCT images were compared with those of in vivo confocal microscopy.

Design and analysis of a cross-type structured-illumination confocal microscope for high speed and high resolution

There have been many studies about a super resolution microscope for many years. A super resolution microscope can detect the physical phenomena or morphology of a biological sample more precisely than conventional microscopes. The structured-illumination microscope (SIM) is one of the technologies that demonstrate super resolution. However, the conventional SIM requires more time to obtain one resolution-enhanced image than other super resolution microscopes. More specifically, the conventional SIM uses three images with a 120° phase difference for each direction and three different directions are image-processed to make one resolution enhancement by increasing the optical transfer function in three directions. In this paper, we present a novel cross structured-illumination confocal microscope (CSICM) that takes the advantage of the technology of both SIM and the confocal microscope. The CSICM uses only two directions with three phase difference images, for a total of six images. By reducing the number of images that must be obtained, the total image acquisition time and image reconstruction time in obtaining the final output images can be decreased, and the confocal microscope provides axial information of the sample automatically. We demonstrate our method of cross illumination and evaluate the performance of the CSICM and compare it to the conventional SIM and the confocal microscope.

Design and Fabrication of a Multi-modal Confocal Endo-Microscope for Biomedical Imaging

Optical microscopes are widely used for medical imaging these days, but biopsy is a lengthy process that causes many problems during the ex-vivo imaging procedure. The endo-microscope has been studied to increase accessibility to the human body and to get in-vivo images to use for medical diagnosis. This research proposes a multi-modal confocal endo-microscope for bio-medical imaging. We introduce the design process for a small endoscopic probe and a coupling mechanism for the probe to make the multi-modal confocal endo-microscope. The endoscopic probe was designed to decrease chromatic and spherical aberrations, which deteriorate the images obtained with the conventional GRIN lens. Fluorescence and reflectance images of various samples were obtained with the proposed endo-microscope. We evaluated the performance of the proposed endo-microscope by analyzing the acquired images, and demonstrate the possibilities of in-vivo medical imaging for early diagnosis.

High-resolution high-speed spectral domain optical coherence tomography

We have designed the spectral domain optical coherence tomography system using a broadband superluminescent diode laser source and home-built spectrometer, which acquires 2D or 3D images with high speed and high resolution. We have also introduced the N-point complex FFT algorithm, which is faster than 2N point real FFT, into the signal processing part, thus shortening signal processing time after image data acquisition. For the sake of convenient measurements, the spectral domain optical coherence tomography was manufactured in the form of a microscope. The volumetric image of a mouse anterior eye could be reconstructed from a few hundred 2D images.

Design of small confocal endo-microscopic probe working under multiwavelength environment

Recently, optical imaging system is widely used in medical purpose. By using optical imaging system specific diseases can be easily diagnosed at early stage because optical imaging system has high resolution performance and various imaging method. These methods are used to get high resolution image of human body and can be used to verify whether the cell is infected by virus. Confocal microscope is one of the famous imaging systems which is used for in-vivo imaging. Because most of diseases are accompanied with cellular level changes, doctors can diagnosis at early stage by observing the cellular image of human organ. Current research is focused in the development of endo-microscope that has great advantage in accessibility to human body. In this research, I designed small probe that is connected to confocal microscope through optical fiber bundle and work as endo-microscope. And this small probe is mainly designed to correct chromatic aberration to use various laser sources for both fluorescence type and reflection type confocal images. By using two kinds of laser sources at the same time we demonstrated multi-modality confocal endo-microscope.

Structured illumination confocal scanning microscope with enhanced optical resolution and acquisition speed

There was a previous research that proposed the structured illumination confocal scanning microscope (SICSM) so as to improve the lateral resolution of the confocal microscope. However, the image acquisition speed of the SICSM was very slow and also an alignment error due to the mechanical rotation of a grating and a slit can easily occur. As a theoretical study, in this paper we propose a new SI method, the cross SI method, which improves lateral resolution and image acquisition speed. Performances of the conventional SI and the proposed SI methods are compared by analysis of the modulation transfer function. The proposed SI method shows similar lateral resolution and can shorten the image acquisition time compared to the conventional SI method. The cross structured illumination confocal microscope (CSICM) is combined with the cross SI pattern optics and the line scanning confocal microscope. We have introduced a 2-D diffractive grating in order to create the cross SI pattern. The effects of the cross SI pattern, intensity and visibility, on the system performance are analyzed. The CSICM has double the lateral resolution of the conventional microscope, an optical sectioning ability and a fast image acquisition speed.

Line scanning confocal microscopy with the use of cross structured illumination

In this paper, we propose new SI method, the cross SI method that improves the lateral resolution and the image acquisition speed. The cross SI pattern is generated by using the 2-D diffractive grating. The acquisition of a total of 6 raw images shortens the image acquisition time. The cross structured illumination confocal microscope (CSICM) is combined with the cross SI pattern generation optics and the line scanning confocal microscope. Performances of the conventional and the cross SI are compared by the analysis of the modulation transfer function. As a result, the cro ss SI method shows similar resolution to conventional SI method. The CSICM has the two times enhanced lateral resolution than the conventional microscope, the optical sectioning ability and the fast image acquisition speed.

Development of in vivo Confocal Microscope Combined with Reflection and Fluorescence Imaging Modes

We propose a new in vivo confocal microscope capable of reflection and fluorescence imaging simultaneously with the use of 488 nm, 660 nm, and 830 nm lasers. We measured the lateral resolution of less than 0.8 μm, the axial resolution of less than 3.5 μm, the focal shift of 1.25 μm, and the imaging depth up to 210 μm. Ex vivo and in vivo images are acquired from bovine artery endothelial cell, mouse, and human skin tissues. Two imaging modes can provide potentials that the accuracy of diagnosis can be improved from different point of views.

Development of in vivo confocal microscope for reflection and fluorescence imaging simultaneously

In-vivo confocal microscope technology can be applied to the medical imaging diagnosis and new drug development. We present an in-vivo confocal microscope that can acquire a reflection image and a fluorescence image simultaneously and independently. To obtain reflection confocal images, we used a linearly polarized diode laser with the wavelength of 830 nm. To acquire fluorescence confocal images, we used two diode lasers with the wavelength of 488 nm and 660 nm, respectively. Because of a broad wavelength bandwidth from visible (488 nm) to near-IR (830 nm), we designed and optimized the optical system to reduce various optical aberrations. With the developed in-vivo confocal microscope, we performed ex-vivo cell imaging and in-vivo imaging of the human skin.