Design of spectrometer based on volume phase grating for near infrared range

In order to design and fabricate a spectrometer for the infrared range widely used in the different applications, Volume Phase Grating (VPG) with. low Polarization Dependence Loss (PDL) and high efficiency has been adopted as the dispersion element. VPG is constructed by coating an optical substrate with a thin film of dichromated. gelatin and exposing the film to two mutually coherent laser beams to form index modulation. The diffraction efficiency for a VPG is governed by Bragg effects. The depth (d) and index modulation contrast of the grating structure control the efficiency at which the light is diffracted when the Bragg condition is satisfied. Gradient index lens with high performance and low aberration are used as collimating system instead of standard lens. The spot diagrams and MTF curve of the collimating lens are shown in the paper. The receive system is InCaAs photodiode (PD) array including 512 pixels with 25 mum pitch. The spectrum resolution of the spectrometer reaches to 0.2nm and wavelength accuracy is 40pm.

Ternary lanthanide (Er3+, Nd3+, Yb3+, Sm3+, Pr3+) complex-functionalized mesoporous SBA-15 materials that emit in the near-infrared range

The tertiary lanthanide complexes [Ln(hfth)(3)phen] (Ln=Er, Nd, Yb, Sm) and [Pr(tfnb)(3)phen] have been Successfully covalently attached in the ordered SBA-15 mesoporous materials via a functionalized 1,10-phenanthroline group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (Phen-Si). The derivative materials [denoted as Ln(hfth)(3)phen-S15 and Pr(tfnb)(3)phen-S15; Ln=Er, Yb, Nd, Sm; hfth=4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate; tfnb=4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate] were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption/desorption.

Fast Discrimination of Commerical Corn Varieties Based on Near Infrared Spectra

The existing methods for the discrimination of varieties of commodity corn seed are unable to process batch data and speed up identification, and very time consuming and costly. The present paper developed a new approach to the fast discrimination of varieties of commodity corn by means of near infrared spectral data. Firstly, the experiment obtained spectral data of 37 varieties of commodity corn seed with the Fourier transform near infrared spectrometer in the wavenurnber range from 4 000 to 12 000 cm (1). Secondly, the original data were pretreated using statistics method of normalization in order to eliminate noise and improve the efficiency of models. Thirdly, a new way based on sample standard deviation was used to select the characteristic spectral regions, and it can search very different wavenumbers among all wavenumbers and reduce the amount of data in part. Fourthly, principal component analysis (PCA) was used to compress spectral data into several variables, and the cumulate reliabilities of the first ten components were more than 99.98%. Finally, according to the first ten components, recognition models were established based on BPR. For every 25 samples in each variety, 15 samples were randomly selected as the training set. The remaining 10 samples of the same variety were used as the first testing set, and all the 900 samples of the other varieties were used as the second testing set. Calculation results showed that the average correctness recognition rate of the 37 varieties of corn seed was 94.3%. Testing results indicate that the discrimination method had higher precision than the discrimination of various kinds of commodity corn seed. In short, it is feasible to discriminate various varieties of commodity corn seed based on near infrared spectroscopy and BPR.

Gold nanoparticle-based near-infrared fluorescent detection of biological thiols in human plasma

In this work, a new fluorescent method for sensitive detection of biological thiols in human plasma was developed using a near-infrared (NIR) fluorescent dye, FR 730. The sensing approach was based on the strong affinity of thiols to gold and highly efficient fluorescent quenching ability of gold nanoparticles (Au NPs). In the presence of thiols, the NIR fluorescence would enhance dramatically due to desorption of FR 730 from the surfaces of Au NPs, which allowed the analysis of thiol-containing amino acids in a very simple approach. The size of Au NPs was found to affect the fluorescent assay and the best response for cysteine detection was achieved when using Au NPs with the diameter of 24 nm, where a linear range of 2.5 x 10(-8) M to 4.0 x 10(-6) M and a detection limit of as low as 10 nM was obtained. This method also demonstrated a high selectivity to thiol-containing amino acids due to the strong affinity of thiols to gold.

Synthesis and Application of Thiadiazoloquinoxaline-Containing Chromophores as Dopants for Efficient Near-Infrared Organic Light-Emitting Diodes

series of a donor-acceptor-donor type of near-infrared (NIR) fluorescent chromophores based on [1,2,5]thiadiazolo[3,4-g]quinoxaline (TQ) as an electron acceptor and triphenylamine as an electron donor are synthesized and characterized. By introducing pendent phenyl groups or changing the pi-conjugation length in the TQ core, we tuned tile energy levels of these chromophores, resulting in the NIR emission in a range from 784 to 868 nm. High thermal stability and glass transition temperatures allow these chromophores to be used as dopant emitters, which can be processed by vapor deposition for the fabrication of organic light-emitting diodes (OLEDs) having the multilayered structure of ITO/MoO3/NPB/Alq(3):dopant emitter/BCP/Alq(3)/LiF/Al. The electroluminescence spectra of the devices based on these new chromophores cover a range from 748 to 870 nm. With 2 wt % of dopant 1, the LED device shows an exclusive NIR emission at 752 nm with the external quantum efficiency (EQE) as high as 1.12% over a wide range of current density (e.g., around 200 mA cm(-2)).

Bi-doped BaF2 crystal for broadband near-infrared light source

Bi-doped BaF2 crystal was grown by the temperature gradient technique and its spectral properties were investigated. The absorption, emission and excitation spectra were measured at room temperature. Two broadband emissions centered at 1070 and 1500 nm were observed in Bi-doped BaF2 crystal. This extraordinary luminescence should be ascribed to Bi-related centers at distinct sites. We suggest Bi2+ or Bi+ centers adjacent to F vacancy defects are the origins of the observed NIR emissions. (C) 2009 Optical Society of America

Study of the effect of alcohol on single human red blood cells using near-infrared laser tweezers Raman spectroscopy

The effect of alcohol solution on single human red blood Cells (RBCs) was investigated using near-infrared laser tweezers Raman spectroscopy (LTRS). In our system, a low-power diode laser at 785 nm was applied for the trapping of a living cell and the excitation of its Raman spectrum. Such a design could simultaneously reduce the photo-damage to the cell and suppress the interference from the fluorescence on the Raman signal. The denaturation process of single RBCs in 20% alcohol solution was investigated by detecting the time evolution of the Raman spectra at the single-cell level. The vitality of RBCs was characterized by the Raman band at 752 cm(-1), which corresponds to the porphyrin breathing mode. We found that the intensity of this band decreased by 34.1% over a period of 25 min after the administration of alcohol. In a further study of the dependence of denaturation on alcohol concentration, we discovered that the decrease in the intensity of the 752 cm(-1) band became more rapid and more prominent as the alcohol concentration increased. The present LTRS technique may have several potential applications in cell biology and medicine, including probing dynamic cellular processes at the single cell level and diagnosing cell disorders in real time. Copyright (c) 2005 John Wiley T Sons, Ltd.

Study of near-infrared nonvolatile two-center holographic recording in LiNbO3:Fe:Rh crystal

The near-infrared nonvolatile holographic recording has been realized in a doubly doped LiNbO3:Fe:Rh crystal by the traditional two-center holographic recording scheme, for the first time. The recording performance of this crystal has been investigated by recording with 633 nm red light, 752 nm red light and 799 nm near-infrared light and sensitizing with 405 nm purple light. The experimental results show that, co-doped with Fe and Rh, the near-infrared absorption and the photovoltaic coefficient of shallow trap Fe are enhanced in this LiNbO3:Fe:Rh crystal, compared with other doubly doped LiNbO3 crystals Such as LiNbO3:Fe:Mn. It is also found that the sensitizing light intensity affects the near-infrared recording sensitivity in a different way than two-center holographic recording with shorter wavelength, and the origin of experimental results is analyzed. (C) 2007 Elsevier GrnbH. All rights reserved.

Near infrared broadband emission from bismuth-dysprosium codoped chalcohalide glasses

We investigate the broadband infrared emission of bismuth doped and bismuth/dysprosium codoped chalcohalide glasses. It is found that the bismuth/dysprosium codoping can drastically enhance the fluorescence as compared with either bismuth or dysprosium doped glasses. Meanwhile, the full width at half maximum of bismuth/dysprosium codoped glasses is over 170 nm, which is the largest value among all the reported rare-earth doped chalcohalide glasses. An ideal way for energy consumption between bismuth and dysprosium ions is supposed. Such improved gain spectra of both bismuth and dysprosium ions may have potential applications in developing broadband fibre amplifiers.

Broadband near-infrared emission from transparent Ni2+-doped silicate glass ceramics

Transparent Ni2+-doped MgO-Al2O3-TiO2-SiO2 glass ceramics were prepared, and the optical properties of Ni2+-doped glass ceramics were investigated. Broadband emission centered at 1320 nm was observed by 980 nm excitation. The longer wavelength luminescence compared with Ni2+-doped Li2O-Ga2O3-SiO2 glass ceramics is ascribed to the low crystal field hold by Ni2+ in MgO-Al2O3-TiO2-SiO2 glass ceramics. The change in optical signals at the telecommunication bands with or without 980 nm excitation was also measured when the seed beam passes through the bulk gain host.(C) 2007 American Institute of Physics.