scholarly journals Through-bottle whisky sensing and classification using Raman spectroscopy in an axicon-based backscattering configuration

2020 ◽  
Vol 12 (37) ◽  
pp. 4572-4578
Author(s):  
Holly Fleming ◽  
Mingzhou Chen ◽  
Graham D. Bruce ◽  
Kishan Dholakia
Keyword(s):  
Raman Spectroscopy ◽  
Laser Beam ◽  
Optical Design

A novel optical design allows through-bottle Raman spectroscopy of alcohols with minimised glass contributions to the signal, by using a shaped laser beam which forms a ring on the glass and a focus within the contents.

A Furnace for Molten Salt Raman Spectroscopy to 800°C

1971 ◽  
Vol 25 (1) ◽  
pp. 82-84 ◽  
Author(s):  
Arvin S. Quist
Keyword(s):  
Raman Spectroscopy ◽  
Laser Beam ◽  
Molten Salts ◽  
Spectroscopic Studies ◽  
Sample Container ◽  
Raman Spectroscopic ◽  
Laser Raman ◽  
Different Types ◽  
Sample Chamber ◽  
Metal Block

A vacuum tight furnace has been constructed and used for laser-Raman spectroscopic studies of molten salts to 800°C. The sample container is positioned within the furnace by a removable metal block, several designs of which have been used with different types of sample containers. The sample under investigation is easily and rapidly aligned in the laser beam by means of micrometer screws located on the positioning table which supports the furnace. The compactness of the entire unit allows it to be readily moved into and out of the sample chamber of the spectrometer.

Applications of the Rotating Solid Sample Technique in Raman Spectroscopy

1972 ◽  
Vol 26 (6) ◽  
pp. 589-593 ◽  
Author(s):  
Howard J. Sloane ◽  
R. B. Cook
Keyword(s):  
Raman Spectroscopy ◽  
General Solution ◽  
Laser Beam ◽  
Resonance Raman ◽  
Solid Sample ◽  
Energy Losses ◽  
Solid Samples ◽  
Pale Yellow ◽  
Sample Technique ◽  
Argon Ion

Use of a rotating solid sample device in the Raman examination of deeply colored highly absorbing samples was investigated. A wide variety of inorganic, organic, and metallorganic compounds ranging in color from pale yellow to orange-red and black were studied using 4880 Å or 5145 Å argon ion excitation. Good quality spectra were obtained from solid samples which previously were either destroyed by conventional static excitation or required defocusing or attenuation of the laser beam with attendant energy losses. The technique appears to offer a general solution to the problem of highly absorbing samples which decompose because of localized overheating by absorption of the source radiation. In some cases, resonance Raman effects may be studied.

Optical Design of CO2 Laser Beam Expanding System with High Variable Expanding Ratio

2015 ◽  
Vol 35 (s2) ◽  
pp. s222002
Author(s):  
姜波 Jiang Bo ◽  
吴越豪 Wu Yuehao ◽  
戴世勋 Dai Shixun ◽  
聂秋华 Nie Qiuhua
Keyword(s):  
Laser Beam ◽  
Co2 Laser ◽  
Optical Design

Characteristics of the defocused spherical Fabry-Pérot interferometer as a quasi-linear dispersion instrument for high resolution spectroscopy of pulsed laser sources

1968 ◽  
Vol 263 (1140) ◽  
pp. 209-223 ◽  
Keyword(s):  
Laser Beam ◽  
Optical Design ◽  
Pulsed Laser ◽  
Resolving Power ◽  
High Resolution Spectroscopy ◽  
Radius Of Curvature ◽  
Spherical Mirror ◽  
Linear Dispersion ◽  
Fabry Perot ◽  
Very High

Defocused spherical mirror Fabry—Pérot etalons, in which the mirror separation is slightly less than the common radius of curvature, produce a multiple-beam fringe pattern of concentric rings, with quasi-linear spectral dispersion over an appreciable annular region corresponding to two free spectral ranges. The characteristics of these interferograms are discussed in relation to their many advantages for pulsed laser spectroscopy. These advantages include: (i) accuracy of frequency difference measurement; (ii) high illumination of the detector with moderate energy density in the laser beam; (iii) ease of alinement and permanent adjustment of the mirrors leading to the attainment in practice of a very high instrumental finesse (N R values of up to 90 have been achieved); (iv) measurement of degree of spatial coherence of laser beam; (v) ease of matching the interferogram to the spatial resolution of the detector. A simple optical path relation determines the positions of the fringes and the location of the quasilinear dispersion region. The interfering wavefronts, formed by multiple reflexion, have been numerically computed and summed to provide information on the finesse, fringe profiles, contrast and optimum conditions of use of this new, very high resolving power (107 to 108) quasi-linear spectrographic disperser. Constructional details are described and optical design criteria are discussed, together with the various experimental arrangements for employing the instrument. Comparison is made with the equivalent confocal and plane Fabry—Pérot etalons and methods of simultaneously measuring

scholarly journals Raman spectrum of group IV nanowires: influence of temperature

2011 ◽  
Vol 1305 ◽  
Author(s):  
J. Anaya ◽  
C. Prieto ◽  
J. Souto ◽  
J. Jiménez ◽  
A. Rodríguez ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectrum ◽  
Laser Beam ◽  
Semiconductor Nanowires ◽  
Group Iv ◽  
Experimental Conditions ◽  
Influence Of Temperature ◽  
Spectrum Of Group ◽  
Group Iv Semiconductor ◽  
Heat Transport Equation

ABSTRACTGroup IV semiconductor nanowires are characterized by Raman spectroscopy. The results are analyzed in terms of the heating induced by the laser beam on the nanowires. By solving the heat transport equation one can simulate the temperature reached by the NWs under the exposure to a laser beam. The results are illustrated with Si and Si1-xGex nanowires. Both bundles of nanowires and individual nanowires are studied. The main experimental conditions contributing to the nanowire heating are discussed.

Raman Signal Enhancement in Deep Spectroscopy of Turbid Media

2007 ◽  
Vol 61 (8) ◽  
pp. 845-854 ◽  
Author(s):  
P. Matousek
Keyword(s):  
Raman Spectroscopy ◽  
Laser Radiation ◽  
Laser Beam ◽  
Near Infrared ◽  
Optical Element ◽  
Disease Diagnosis ◽  
Pharmaceutical Products ◽  
Turbid Media ◽  
Raman Signal

A new, passive method for enhancing spontaneous Raman signals for the spectroscopic investigation of turbid media is presented. The main areas to benefit are transmission Raman and spatially offset Raman spectroscopy approaches for deep probing of turbid media. The enhancement, which is typically several fold, is achieved using a multilayer dielectric optical element, such as a bandpass filter, placed within the laser beam over the sample. This element prevents loss of the photons that re-emerge from the medium at the critical point where the laser beam enters the sample, the point where major photon loss occurs. This leads to a substantial increase of the coupling of laser radiation into the sample and consequently an enhanced laser photon–medium interaction process. The method utilizes the angular dependence of dielectric optical elements on impacting photon direction with its transmission spectral profile shifting to the blue with increase in the deviation of photons away from normal incidence. This feature enables it to act as a unidirectional mirror passing a semi-collimated laser beam through unhindered from one side, and at the other side, reflecting photons emerging from the sample at random directions back into it with no restrictions to the detected Raman signal. With substantial restrictions to the spectral range, the concept can also be applied to conventional backscattering Raman spectroscopy. The use of additional reflective elements around the sample to enhance the Raman signal further is also discussed. The increased signal strength yields higher signal quality, a feature important in many applications. Potential uses include sensitive noninvasive disease diagnosis in vivo, security screening, and quality control of pharmaceutical products. The concept is also applicable in an analogous manner to other types of analytical methods such as fluorescence or near-infrared (NIR) absorption spectroscopy of turbid media or it can be used to enhance the effectiveness of the coupling of laser radiation into tissue in applications such as photodynamic therapy for cancer treatment.

scholarly journals A Study of High-Efficiency Laser Headlight Design Using Gradient-Index Lens and Liquid Lens

2020 ◽  
Vol 10 (20) ◽  
pp. 7331
Author(s):  
Yi-Chin Fang ◽  
Yih-Fong Tzeng ◽  
Chan-Chuan Wen ◽  
Chao-Hsien Chen ◽  
Hsiao-Yi Lee ◽  
...  
Keyword(s):  
Laser Beam ◽  
Light Source ◽  
High Efficiency ◽  
Optical Design ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Gradient Index ◽  
High Beam ◽  
Liquid Lens ◽  
Gradient Index Lens

In the field of vehicle lighting, due to the diode laser, its small size and high energy conversion efficiency, it can be effectively used as the headlight source of high beam. In recent years, it was adopted by European advanced car manufacturers as a new generation of automotive headlight lighting products. The current mature technology on the market is to extend the laser beam by means of reflection and to use a single high-power laser as the light source to meet the needs of surface lighting. In this research, we propose a new integrated optical design for an automotive headlight system with the rod lens, gradient-index lens (GRIN lens) and freeform lens to expand the laser beam. With regard to the diffusion of the beam by reflection and refraction, the liquid lens is used as a switch for the high beam and low beam lights to meet the needs of vehicle lighting functions and to use low-power diode lasers to synthesize the array light source. Compared with the 24-W LED headlight module available in the current market, the energy saved by this proposed optical design can increase efficiency by an average of 33%. The maximum illuminance is 56.6 lux in the high-beam mode, which is 18% higher than the standard value. Let the laser light meet the lighting requirements of regulatory standard values even beyond.

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