We introduce a novel approach for measuring glucose concentration through mid-infrared transmission spectroscopy. This method utilizes a high-speed infrared spectroscopic technique employing a mid-infrared wavelength-swept (center wavelength 9.3 μm) pulse quantum cascade laser (QCL). Additionally, a special asynchronous signal control method is developed to reduce the measurement time to 20 ms. With the high power of the QCL and the proposed algorithm, the concentration of glucose solution samples can be accurately measured.
A highly sensitive near-infrared spectroscopy technique was developed for remote sensing of concrete structures. We have employed a multichannel Fourier transform spectroscopy to achieve this purpose which use an area sensor instead of an often-used linear sensor. In this study, chloride concentrations on the surface of concrete were evaluated.
By using a “slit-less” Fourier-transform spectrometer, we demonstrate that cardiac-pulsation amplitude of absorbance can be extracted from 3.5-level absorbance unit (AU) spectra of a human fingertip with a resolution of < 0.0005 AU and a spectral resolution of < several tens of nanometers, even with a low-cost “non-cooled” NIR detector. From the extracted spectrum over 1,000-1,400 nm, the average amounts of pulsating blood components (water, HbO2, and lipids/proteins) in a fingertip are deduced in the sub-milligram order. The results indicate the capacity of the spectrometer for a portable non-invasive blood monitor as well as for a high-end analytic instrument.
Two-dimensional distribution of oxygen saturation levels across the human retina is predicted by measuring the multispectral images. A liquid crystal tunable filter is used to scan wavelength ranging from 500 to 700 nm to acquire the multispectral images with the spectral resolution of 20 nm. After preprocessing reflected spectra at every pixel to cancel common offsets and amplifications, the partial least squares regression is adopted to estimate the oxygen saturation levels at each pixel point. All the resulted response values compose the oxygen saturation level map. The effects of preprocessing types on the predicted oxygen saturation levels are also discussed.
The straightness of a linear stage consists of three rotation angle errors and two lateral displacement errors. We show a novel straightness measurement system by using laser beams, simple optical components and position sensing devices.
We demonstrate light propagation in a novel type of optical waveguide, which consisting of periodically arrayed dielectric particles. Advantages provided by this waveguide are that dynamic optical interconnection can be realized and that a multichannel waveguide is easily formed. To fabricate the system of periodic micro cavities, we used polystyrene- latex particles that have a uniform size of 15.6 micrometers . The second harmonic of a Nd:YVO4 laser, the wavelength 532 nm, was introduced to the sample substrate in order to excite the fluorescence of Rhodamine 6G. Some discrete frequencies of fluorescence were selected to agree with the phase matching condition and produce a resonance mode in a microsphere. Part of the energy transferred to the adjacent spheres via evanescent light. Thus, some discrete frequencies of the fluorescence propagated through the microspheres. Since the particles are arrayed symmetrically, the resonance light can propagate in three different directions. The propagating direction can be controlled to regulate the location of a focused spot. In addition, if you illuminate the next microsphere, the excited light propagates in the next line of arrayed microspheres. The assembled microspheres can be taken as a multichannel waveguide.
Optical tweezer is a powerful tool for manipulating samples under a microscope. However, this technique is limited to transparent objects because it has been believed that it is the light refraction that play a significant role to manipulate the microscopic objects. We took notice of a optical force generated by a surface diffraction wave, so called creeping wave [1] , and found that it can be applicable to trap metallic objects [21. In this presentation, we show that gold Mie particles (0.5 - 3.0 im in diameter) can be trapped optically in two dimensions.
The near-field scanning optical microscope (NSOM) has been developed to extract optical information from a nanometric area of sample. The amount of information contained in an NSOM image is potentially vast but it could not yet be fully exploited because of the need for a more complete understanding of the effects of the probe-sample interaction on the imaging process. A better understanding will lead to an unambiguous analysis of an NSOM image and will make the NSOM a reliable imaging tool. In this paper, we present the analysis of NSOM imaging through the numerical calculation based on an electromagnetic-theory-based algorithm,called Finite-Difference Time-Domain method (FDTD).
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