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]).
We proposed the imaging-type 2-dimensional Fourier spectroscopy that is a near-common-path interferometer with
strong robustness against mechanical vibrations. We introduced the miniature uncooled infrared microbolometer arrays
for smartphone (e.g. product name: FILR ONE price: around 400USD). And we constructed the phase-shifter with the
piezo impact drive mechanism (maker: Technohands.co.Ltd., stroke: 4.5mm, resolution: 0.01μm, size: 20mm, price:
around 800USD). Thus, we realized the palm-size mid-infrared spectroscopic imager [size: L56mm×W69mm×H43mm
weight: 500g]. And by using wide-angle lens as objective lens, the proposed method can obtain the wide-field 2-
dimensional middle-infrared (wavelength: 7.5-13.5[μm]) spectroscopic imaging of radiation lights emitted from human
bodies itself
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).
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.
We are aiming at the realization of the measurement technology for the biological-substance distributions, such as sebum, on entire faces at the daily-life environment. We proposed the imaging-type 2-dimensional Fourier spectroscopy [1] that is the palmtop-size portable measurement apparatus and has the strong robustness for mechanical vibrations. And the proposed method can measure the wide-field 2-dimensional middle-infrared spectroscopic-imaging of radiation lights emitted from human bodies itself without light sources. In the proposed method, we install the phase-shifter, that can give an arbitrary phase difference for the half-flux of objective beams, at the optical Fourier transform plane of the infinity corrected optical system. The near-common-path interferometer that is a phase-shift interferometer between objective beams can be realized. In this proposed method, the emitted rays from each single-bright-point on measurement surfaces can interfere with each other. Thus, even if the middle infrared-lights from human bodies are the spatially incoherent light, we can acquire the interferograms at each pixel on an imaging array-device in accordance with the amount of phase shift as the 2-dimensional image-intensity changes. We demonstrated the feasibility of the middle infrared spectroscopic imaging of whole human faces without active illuminations.
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