Browsing by Author "Nakada, S"

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Embargo
Compact optical system for imaging type two-dimensional spectroscopic tomography
(IEEE, 2013-12-17) Abeygunawardhana, P. K. W; Nakada, S; Suzuki, S; Nishiyama, A; Ishimaru, I
Spectroscopic measurement is being widely used for non-invasive blood sugar measurement in recent past. Imaging type two-dimensional spectroscopic tomography has been designed using wave front division interferometer. Variable phase filter, which has fixed mirror and movable mirror, has been used to introduce the phase shift between rays. Capability of measuring biogenic substances using this method has been proved. For the quantitative analysis with high accuracy, the correction of the background such as the light-source fluctuation and the phase-shift uncertainty is inevitable issue. Background noises and vibrations in test bed are part of the causes that could results such errors. This paper proposes a new closed optical system to improve the system performance. One-shot type spectroscopic tomography and Smooth Impact Drive Mechanism are used here.
Open Access
Quantitative measurement of biological substances in daily-life environment with the little-finger-size one-shot spectroscopic tomography
(International Society for Optics and Photonics, 2014-02-28) Ishida, A; Sato, S; Nakada, S; Suzuki, S; Abeygunawardhana, P. K. W; Wada, K; Nishiyama, A; Ishimaru, I
In daily-life environment, the quantitative measurement of biological substances, such as the blood glucose level in the human skin, is strongly required to realize the non-invasive healthcare apparatus. Fourier-spectroscopic-tomography of the little-finger-size with high time-resolution and with the strong robustness for mechanical vibrations is proposed. The proposed method is a kind of near-common-path interferometer with spatial phase-shift method. We install the transmission-type relative-inclined phase-shifter on the optical Fourier transform plane of the infinity corrected optical system. The phase shifter is constructed with the cuboid and wedge prisms to give the relative phase-shift spatially between each half-flux of the objective beams. The interferograms from each single-bright-point on an objective surface in a line are formed as fringe patterns on 2-dimensional imaging array devices. And because the proposed method is based on the imaging optics, only emitted rays from a focal plane can contribute forming of interferograms. Thus, the measurement plane can be limited onto the focal plane only. From the spectroscopic tomography, only at a localized vessel area in human skins, we can get the pinpointed near-infrared spectroscopic data. And we can expect the improvement of the determination precision, because a Fourier spectroscopic-character is acquired from multiple intensity data in accordance with amount of phase-shift. From the statistical point of view, the gradation of detector is improved with the square root of sample number, based on t-distribution. We constructed the statistical model to assure the determination accuracy, and demonstrated the feasibility of the glucose sensor using liquid cells.