Papers by Keyword: Optical Detection

Abstract: The purpose of this work was to determine whether novel hybrid nanomaterials obtained in mild synthesis conditions between a Pt (II) metalloporphyrin, namely: Pt (II) 5,10,15,20-tetra (4-methoxy-phenyl)-porphyrin (PtTMeOPP) and nanoGold (n-Au) offer better recognition or detection properties toward hydrocortisone than the solely uncombined compounds. The Pt-porphyrin, gold-colloid and the hybrid nanomaterials were synthesized and characterized by UV-vis, FT-IR, ¹H-NMR, AFM and TEM microscopy. For the concentrations of hydrocortisone that have relevance for medical field, covering the range of 10^-8 to 10^-7 M, an excellent correlation of 0.99 was obtained between the intensity of absorption of the n-Au-PtTMeOPP hybrid plasmon and the hydrocortisone concentration, measured in THF-water system. So, this n-Au-PtTMeOPP conjugate system can be further developed to implement an accurate hydrocortisone optical sensor.

Abstract: A novel space environment effects equivalence model used for space optical detection is proposed in this paper. In this model, the effects on the space optical detection system are equivalent to defocus, image motion, vibration and noise. Besides, the equivalent modulation transfer function of the space optical detection system is presented. The proposed model can avoid analyzing so many space influence factors at the same time. Moreover, the model can provide some basis to determine the parameters of the detection system which are difficult to measure. Some numerical simulations are made to test the validity and capability of the proposed model.

Abstract: The experimental investigation on transparent solid/solid (Aluminum and Plexiglas) interface leaky waves generated by a pulse laser and detected with a photo elastic effect technique is reported. Three waves Lateral wave, Leaky Rayleigh (LR) wave and Leaky Interface wave (IW) are detected successfully; The velocity of the detected interface wave is in good agreement with theoretical calculation and the attenuation characteristic of the two Leaky waves is also in accordance with the theoretical prediction. The Leaky waves propagate along the weak bonding interface is also measured, it was found with the continue Epoxy solidifying, the wave amplitude gradually decrease and the two Leaky waves are more difficult to distinguish. The successful measurement should improve the scientific and technological potential for the research of solid/solid interface waves.

Abstract: In order to establish a larger sensing area (10m×10m) and perform higher precision of the measurement system during barrel weapon test of vertical target dispersion, an optical detector is provided additionally in acoustic array to form a new measurement model, which does not only have the advantage of large sensing area, but also of higher precision. The paper presents and gives the measuring formula of the measuring model, and provides analysis on the measurement error. The simulation result showes that the errors of x and y Coordinates are 5mm and 15mm respectively.

Abstract: Luminescent sensors are chemical systems that can deliver information on the presence of selected analytes through the variations in their luminescence emission. With the advent of luminescent nanoparticles several new applications in the field of chemical sensing were explored. Among them, quantum dots (QD) represent inorganic semiconductor nanocrystals that are advantageous over conventional organic dyes from many different points of view. In this short review, the optical detection of various analytes using QD-based probes/sensors is presented and significant sensors characteristics are discussed. The biosensing approaches are not included in this article.

Abstract: In this work, the results on using biosensor composed from quantum dots as transducer and acetylcholinesterase enzymes (AChE) to detect pesticides optically are presented. The used quantum dots were CdTe, CdSe/ZnS 10 monolayer (ML) and CdSe/ZnSe2ML/ZnS 8 ML – the brand new thick-shell quantum dots (QD). The study results pointed out that the CdSe/ZnS 10 ML and CdSe/ZnSe 2ML/ZnS 8ML quantum dots best fit for the role of transducers in biosensors. In the biosensor, acetylthiocholine (ATCh) is used as indicator for the AChE enzymes to work, since it is a very powerful hydrolyte with the presence of AChE enzymes. Moreover, the organophosphorus (OP) pesticides are the inhibitors for the AChE enzymes, thus, by the biosensors that we designed, we can detect pesticides by the change in photoluminescence (PL) intensity of QDs, with the detection of OP like parathion methyl is 0.05 ppm, and acetamiprid is 2.5 ppm.

Abstract: Accurate measurement of the aerosols concentration is important in many applications of aerosol science. Here we compare the adequacy of a peak function with the profiles distribution given by a particle counter (CPC) classified in the size range 5 to 500 nm, issued in a machine shop. The particle counter uses a laser source and an optical system for the detection of particles. Our experiments lead to some underestimation of the profile. This underestimation corresponds with the parasitic phenomena of air bubbles and water droplets which are recorded by default as particles. The results of this study underscore the compatibility of a function Gaussian modified by exponential with the distribution profile given by the particle counter (99%).

Abstract: The Young’s modulus of micromechanical silicon films is very different from bulk silicon structures. It is very meaningful to test Young’s modulus of micromechanical silicon films in related studies. Owing to its small and fragile characterstics, a suitable non-contact and nondestructive method is needed to test the Young’s modulus of micromechanical silicon films with plate-like and beamlike structures. Utilizing acoustic excitation and optical detection method based on theoretical analysis, a new resonant method is presented to determinate Young’s modulus of micromachined silicon films. By using this novel method, more accurate results have been achieved and the measuring error is 11%, better than the reported 14%.