ワンショットデジタルホログラフィによる赤血球の三次元計測

Abstract

In these years, because of applications for medical analysis, such as biopsy, demand of 3D microscope is arising. Typical existing 3D microscopes are Scanning Electron Microscope (SEM) and confocal laser scanning microscopy (CLSM). SEM is a type of electron microscope that produces images of an object by scanning it with a focused beam of electrons. The electrons interact with atoms in the object, producing various signals that can be detected and that contain information about the sample’s surface topography and composition. However, SEM needs a vacuum system during measurement, and it is big size and price high. CLSM is a technique for obtaining high-resolution optical images with depth selectivity. It is its ability to acquire in-focus images from selected depths, a process known as optical sectioning. Images are acquired point-by-point and reconstructed with a computer, allowing 3D reconstructions of topologically complex objects. However, 3D measurement using CLSM is time consuming because it has to scan an object point-by-point, and 3D measurement accuracy of CLSM is about 1μm which is difficult to measure nano-structure objects. To resolve problems in existing 3D microscopes, 3D microscope using single-shot phase-shift digital holography is proposed in this paper. In proposal 3D microscope, at first, a Michelson interferometer and general optical components are used, so reduction in system size and price-down can be realized easily. Second, the proposal 3D measurement method, single-shot phase-shift digital holography, uses Fourier-transform method of fringe-pattern which has been used for interferometry originally. Using the proposal method, 3D shape of an object can be measured in real-time(60ms) with 5.5nm accuracy in height direction and 0.59μm resolution in XY plane. Finally, 3D shapes of human red blood cells are measured in measurement experiment. According to result of experiment, we conclude that the proposed 3D microscope can be applied to the field of precision medical analysis.