Faculty of Computing

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Now showing 1 - 10 of 12
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    PublicationEmbargo
    Precision Controlled Variable Phase Filter for Imaging Type Two-Dimensional Spectroscopic Tomography
    (IEEE, 2013-09-01) Abeygunawardhana, P. K. W; Suzuki, S; Ishimaru, I; Nishiyama, A
    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. Variable phase filter has a piezoelectric actuator which has the stroke of 30μm. However, it is not enough for mid-infrared application. Smooth Impact drive mechanism with longer stroke was used here. However, smooth control is challengeable. This paper proposed the control of SIDM using PID control and Pseudo inverse differentiation. Proposed controller implemented and experiment result proved the effectiveness of proposed method.
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    PublicationEmbargo
    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.
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    PublicationEmbargo
    Signal conditioning for imaging type Fourier spectroscopy using Independent Component Analysis
    (IEEE, 2014-10-22) Abeygunawardhana, P. K. W; Fujiwara, M; Suzuki, S; Ishimaru, I
    Biomedical Signal Processing, in which Spectroscopic measurement plays a crucial role, has been the center of attraction by many researchers during the past few years. Two - dimensional imaging type Fourier spectroscopy is a technique which can limit the measuring depth into focal plane. Although the various substances including bio genic substances can be measured, measured results include two or more signals mixed together. In this paper, Independent Component Analysis known as ICA has been used to separate those mixed signals.
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    PublicationOpen Access
    Signal Improvement in Imaging Type Two-Dimensional Fourier Spectroscopy for Wild-Field Internal Non-Destructive Inspection
    (2015-01) Abeygunawardhana, P. K. W; Fujiwara, M; Suzuki, S; Ishimaru, I; Nishiyama, A
    —Imaging type two-dimensional Fourier spectroscopy is the wave front-division interferometer which limits the measurement depth into focal plane. This method has shown the potential in many areas such as measurement of biological substances and non-destructive inspections. Presence of noise in the signal may affect the end result of test. This paper proposes the algorithm for improving spectral data by finding low noisy point and filtering them. Cross correlation with median noisy signal is used to find the best signal to be considered. Experiment was conducted for testing fingerprint, alcohol measurement and measurement of ink. Proposed algorithm was conducted for the data obtained from ink measurement.
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    PublicationOpen Access
    Spectrum correction considering light source fluctuation for non-invasive blood glucose sensing
    (SPIE, 2014-03-04) Suzuki, S; Ishida, A; Abeygunawardhana, P. K. W; Wada, K; Nishiyama, A; Ishimaru, I
    The purpose of this study is to correct baseline shift in absorbance spectrums caused by light source fluctuation. To improve quantitative evaluation performance of blood glucose level, baseline shift is corrected by multiple scatter correction (MSC). Moreover, to increase the effect of the MSC, water vapor absorbance is subtracted, and relative glucose absorbance are calculated by dividing with hemoglobin absorbance at 1544 [cm-1]. In order to verify the effectiveness of the proposed spectrum correction method, light source fluctuation is simulated on the Fourier transform infrared spectroscopy (FT-IR), and we apply the proposed method to the spectrums measured by FT-IR. From the simulation results, the baseline shift was successfully reduced by proposed method.
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    PublicationOpen Access
    In-situ monitoring of blood glucose level for dialysis machine by AAA-battery-size ATR Fourier spectroscopy
    (Optical Society of America, 2015-06-21) Hosono, S; Shun, S; Ishida, A; Suzuki, Y; Inohara, D; Kosuke, N; Abeygunawardhana, P. K. W; Suzuki, S; Nishiyama, A; Kenji, W. A. D. A; Ishimaru, I
    For blood glucose level measurement of dialysis machines, we proposed AAA-battery-size ATR (Attenuated total reflection) Fourier spectroscopy in middle infrared light region. The proposed one-shot Fourier spectroscopic imaging is a near-common path and spatial phase-shift interferometer with high time resolution. Because numerous number of spectral data that is 60 (= camera frame rare e.g. 60[Hz]) multiplied by pixel number could be obtained in 1[sec.], statistical-averaging improvement realize high-accurate spectral measurement. We evaluated the quantitative accuracy of our proposed method for measuring glucose concentration in near-infrared light region with liquid cells. We confirmed that absorbance at 1600[nm] had high correlations with glucose concentrations (correlation coefficient: 0.92). But to measure whole-blood, complex light phenomenon caused from red blood cells, that is scattering and multiple reflection or so, deteriorate spectral data. Thus, we also proposed the ultrasound-assisted spectroscopic imaging that traps particles at standing-wave node. Thus, if ATR prism is oscillated mechanically, anti-node area is generated around evanescent light field on prism surface. By elimination complex light phenomenon of red blood cells, glucose concentration in whole-blood will be quantify with high accuracy. In this report, we successfully trapped red blood cells in normal saline solution with ultrasonic standing wave (frequency: 2[MHz]).
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    PublicationEmbargo
    Quantitative spectroscopic tomography for the non-invasive measurement of the biogenic-substances
    (IEEE, 2012-11-21) Qi, W; Kojima, D; Sato, S; Suzuki, S; Abeygunawardhana, P. K. W; Nishiyama, A; Ishimaru, I
    The non-invasive blood sugar sensor by using imaging-type 2-dimensional Fourier spectroscopy is to be realized in this work. The spectroscopic imaging, that observes the biological tissue by the dark-field image, can measure the biogenic substance quantitatively such as the glucose concentration. 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. Thus, the quantitative bandpass plate on which the grating is locally formed has been proposed in this paper. Here, the diffractive light, whose diffraction angle depends on the wavelength, has been used as the reference light Object lens is used to narrow down the reference light and narrowed band pass diffraction light is obtained. The changes of imaging intensities with interference phenomenon on whole area of the observation image can be confirmed using the quantitative band pass filter. Thus, the light-source fluctuation from the amplitude of the reference light intensity and the phase-shift uncertainly from the interference-phase can be corrected respectively. In this paper, the theoretical accuracy of Fourier spectroscopy calculated with the numerical simulation and the background correction method of the spectral-absorption-index image by the diffraction grating type quantitative bandpass plate are presented.
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    PublicationOpen Access
    Measurement of the mid-infrared Fourier spectroscopic imaging of whole human face by portable apparatus (size: 50* 50 mm, weight: 200 g)
    (International Society for Optics and Photonics, 2014-11-20) Qi, W; Suzuki, Y; Fujiwara, M; Saito, T; Suzuki, S; Abeygunawardhana, P. K. W; Wada, K; Nishiyama, A; Ishimaru, I
    In the daily living space, measurement of the biological-substance distributions such as sebum can be realized by the proposed method of imaging-type 2-dimensional Fourier spectroscopy. This method has the strong robustness for mechanical vibrations. So, the spectrometer (size: 50*50mm, weight: 200g) can be produced without anti-vibration mechanism. Moreover, the phase shifter is a core part of the spectrometer, and it is constructed by the low-price bimorph type actuator which is depending on the vibration control of the piezoceramic in proposed method. It is appropriate as the actuator of the phase shifter from the evaluation results of the actuator straightness and position accuracy in the midinfrared region. As we know, the Fourier spectroscopy has a high light utilization efficiency. Therefore, the low price microbolometer can be used as the imaging sensor. So, the low-price (10,000 U.S. dollars), compact and high portability spectrometer can be produced. Furthermore, the much higher position accuracy in the short wavelength region is requested as we know, the phase shift correction method has been proposed. In this paper, high performance evaluations of the portable spectroscopy apparatus have been discussed by using the CO2 laser spectroscopy results in the midinfrared region. Then, the phase shift correction method was explained. At the end, we demonstrated the feasibility of the mid-infrared imaging of whole human faces without active illuminations.
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    PublicationOpen Access
    Proposal of AAA-battery-size one-shot ATR Fourier spectroscopic imager for on-site analysis: Simultaneous measurement of multi-components with high accuracy
    (International Society for Optics and Photonics, 2015-03-12) Hosono, S; Qi, W; Sato, S; Suzuki, Y; Fujiwara, M; Hiramatsu, H; Suzuki, S; Abeygunawardhana, P. K. W; Wada, K; Nishiyama, A; Ishimaru, I
    For simultaneous measurement of multi-components on-site like factories, the ultra-compact (diameter: 9[mm], length: 45[mm], weight: 200[g]) one-shot ATR (Attenuated Total Reflection) Fourier spectroscopic imager was proposed. Because the proposed one-shot Fourier spectroscopic imaging is based on spatial-phase-shift interferometer, interferograms could be obtained with simple optical configurations. We introduced the transmission-type relativeinclined phase-shifter, that was constructed with a cuboid prism and a wedge prism, onto the optical Fourier transform plane of infinity corrected optical systems. And also, small light-sources and cameras in the mid-infrared light region, whose size are several millimeter on a side, are essential components for the ultra-compact spectroscopic configuration. We selected the Graphite light source (light source area: 1.7×1.7[mm], maker: Hawkeye technologies) whose radiation factor was high. Fortunately, in these days we could apply the cost-effective 2-dimensional light receiving device for smartphone (e.g. product name: LEPTON, maker: FLIR, price: around 400USD). In the case of alcoholic drinks factory, conventionally workers measure glucose and ethanol concentrations by bringing liquid solution back to laboratories every day. The high portable spectroscopy will make it possible to measure multi-components simultaneously on manufacturing scene. But we found experimentally that absorption spectrum of glucose and water and ethanol were overlapped each other in near infrared light region. But for mid-infrared light region, we could distinguish specific absorption peaks of glucose (@10.5[μm]) and ethanol (@11.5[μm]) independently from water absorption. We obtained standard curve between absorption (@9.6[μm]) and ethanol concentration with high correlation coefficient 0.98 successfully by ATR imaging-type 2-dimensional Fourier spectroscopy (wavelength resolution: 0.057[μm]) with the graphite light source (maker: Hawkeye technologies, type: IR-75).
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    PublicationOpen Access
    Novel algorithm for background correction of the quantitative spectroscopic tomography of the biogenic-substances
    (International Society for Optics and Photonics, 2013-02-25) Abeygunawardhana, P. K. W; Qi, W; Kojima, D; Suzuki, S; Nishiyama, A; Ishimaru, I
    The non-invasive blood sugar sensor by using imaging-type 2-dimensional Fourier spectroscopy is to be realized in this work. The spectroscopic imaging, that observes the biological tissue by the dark-field image, can measure the biogenic substance quantitatively such as the glucose concentration. 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. Thus, the quantitative band-pass plate on which the grating is locally formed has been already proposed by [1]. In that paper, the diffractive light, whose diffraction angle depends on the wavelength, has been used as the reference light. Object lens is used to narrow down the reference light and narrowed band pass diffraction light is obtained. The changes of imaging intensities with interference phenomenon on whole area of the observation image can be confirmed using the quantitative band pass filter. This paper proposed background correction method of the interferogram in spectroscopic tomography. Correction algorithm mainly contained two parts as light source fluctuation error correction and phase shift error correction.