Naoki Konishi

Real-time visualization of retinal microcirculation by laser flowgraphy

A new real-time measuring system is developed to visualize the blood flow map of the human retina using dynamic laser speckle effects and a hardware logic circuit. The retina is illuminated with a diode laser spot through a retinal camera, and the speckle field at the image plane of the spot is scanned by an area sensor. The output signal is analog-to-digital (AID) converted and the blur rate of the intensity at each pixel point is evaluated through a hardware logic circuit specially devel- oped for this system. The results are displayed in 2-D color maps suc- cessively at a rate of 16 frames/s, which allows the real-time observation of retinal blood flow.

Depth Extraction of Partially Occluded 3D Objects Using Axially Distributed Stereo Image Sensing

There are several methods to record three dimensional (3D) information of objects such as lens array based integral imaging, synthetic aperture integral imaging (SAII), computer synthesized integral imaging (CSII), axially distributed image sensing (ADS), and axially distributed stereo image sensing (ADSS). ADSS method is capable of recording partially occluded 3D objects and reconstructing high-resolution slice plane images. In this paper, we present a computational method for depth extraction of partially occluded 3D objects using ADSS. In the proposed method, the high resolution elemental stereo image pairs are recorded by simply moving the stereo camera along the optical axis and the recorded elemental image pairs are used to reconstruct 3D slice images using the computational reconstruction algorithm. To extract depth information of partially occluded 3D object, we utilize the edge enhancement and simple block matching algorithm between two reconstructed slice image pair. To demonstrate the proposed method, we carry out the preliminary experiments and the results are presented.

Development of active state measurements system for the cells in solution

With the objective of developing a system to quantitatively measure the active states of microorganisms and cells by using laser speckle, we performed simulations to determine the optimum system parameters. In this study, the obtained optimum parameters were applied, dynamic speckle was observed by measuring moving objects with an optical device, and the parameters obtained from the dynamic speckle were evaluated.

Development of the portable blood flow measurement system using Laser Speckle Flowgraphy

A new blood flow measurement system using Laser Speckle Flowgraphy was developed to measure the blood flow easily. The measurement system loads a small display unit to view the results of the measurements without PC. In addition, the system consists of a microcontroller, line sensor, laser unit. We integrated these devices into the system so that the system was miniaturized. We made an experiment of measuring blood flow value by the system.

Analyses of blood flow map obtained by Real-Time Laser Flowgrapy

A new system, which we call the Real-Time Laser Flowgraphy, have been developed to visualize blood flow in retina using laser-speckle effects.In this paper, we build up a graphical user interface to ease the handling with a mouse operation. Someadditional programs are developed to measure the width of the vessels, and to visualize pulsation of the blood flow in 3-D color graphics. The blood flow of human retinal arterioles and veinules areanalyzed with this system. It is found that the blood flow evaluated from BR(the Blur Rate of the speckles) is influenced by the width of the vessels.