CIE TN 010:2019 Determination of the Optical Beam Axis, Centre Beam Intensity, and Beam Angle of Directional Light Sources

2019 ◽  
Author(s):  
A Bergen ◽  
P Blattner ◽  
A Klej ◽  
Q Li ◽  
T Menegotto ◽  
...  
Keyword(s):  
Optical Beam ◽  
Beam Intensity ◽  
Beam Axis ◽  
Light Sources ◽  
Beam Angle

scholarly journals Enhancement of Photoacoustic Signal Strength with Continuous Wave Optical Pre-Illumination: A Non-Invasive Technique

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1190
Author(s):  
Anjali Thomas ◽  
Souradip Paul ◽  
Joy Mitra ◽  
Mayanglambam Suheshkumar Singh
Keyword(s):  
Methylene Blue ◽  
Continuous Wave ◽  
Optical Power ◽  
Signal Strength ◽  
Optical Beam ◽  
Clinical Translation ◽  
Optical Absorption Coefficient ◽  
Invasive Technique ◽  
Light Sources ◽  
Chicken Tissue

Use of portable and affordable pulse light sources (light emitting diodes (LED) and laser diodes) for tissue illumination offers an opportunity to accelerate the clinical translation of photoacoustic imaging (PAI) technology. However, imaging depth in this case is limited because of low output (optical) power of these light sources. In this work, we developed a noninvasive technique for enhancing strength (amplitude) of photoacoustic (PA) signal. This is a photothermal-based technique in which a continuous wave (CW) optical beam, in addition to short-pulse ~ nsec laser beam, is employed to irradiate and, thus, raise the temperature of sample material selectively over a pre-specified region of interest (we call the process as pre-illumination). The increase in temperature, in turn enhances the PA-signal strength. Experiments were conducted in methylene blue, which is one of the commonly used contrast agents in laboratory research studies, to validate change in temperature and subsequent enhancement of PA-signal strength for the following cases: (1) concentration or optical absorption coefficient of sample, (2) optical power of CW-optical beam, and (3) time duration of pre-illumination. A theoretical hypothesis, being validated by numerical simulation, is presented. To validate the proposed technique for clinical and/or pre-clinical applications (diagnosis and treatments of cancer, pressure ulcers, and minimally invasive procedures including vascular access and fetal surgery), experiments were conducted in tissue-mimicking Agar phantom and ex-vivo animal tissue (chicken breast). Results demonstrate that pre-illumination significantly enhances PA-signal strength (up to ~70% (methylene blue), ~48% (Agar phantom), and ~40% (chicken tissue)). The proposed technique addresses one of the primary challenges in the clinical translation of LED-based PAI systems (more specifically, to obtain a detectable PA-signal from deep-seated tissue targets).

scholarly journals Multivariate Analysis of Photoacoustic Spectra for the Detection of Short-Chained Hydrocarbon Isotopologues

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2266 ◽  
Author(s):  
Alain Loh ◽  
Marcus Wolff
Keyword(s):  
Multivariate Analysis ◽  
Continuous Wave ◽  
Light Sources ◽  
Least Squares Regression ◽  
Detection Scheme ◽  
Concentration Determination ◽  
Multiple Measurements ◽  
Interband Cascade Lasers ◽  
Cascade Lasers

We report, to our knowledge, the first optical detection scheme for short-chained hydrocarbon isotopologues. The sensor system is based on photoacoustic spectroscopy (PAS). Two continuous wave, thermoelectrically cooled, distributed feedback interband cascade lasers (DFB-ICLs) with emission wavelengths around 3.33 and 3.38 μm, respectively, served as light sources. The investigations comprised the main stable carbon isotopologues of methane (12CH4, 13CH4), ethane (12CH3-12CH3, 13CH3-12CH3, 13CH3-13CH3), and propane (12CH3-12CH2-12CH3, 13CH3-12CH2-12CH3). They were selected because of their importance for numerous applications from climate and planetary research to natural gas exploration. Multiple measurements of single components in nitrogen and synthetic mixtures were conducted at room temperature and atmospheric pressure. Depending on the investigated hydrocarbon isotopologue, detection limits ranging from 0.043 ppmv to 3.4 ppmv were achieved. For a selective concentration determination, multivariate analysis (MVA) was applied. Partial least-squares regression (PLSR) was used to calculate concentrations from the PA spectra. The implementation of MVA has shown that the PA setup in principle works reliably and that the selective concentration determination of short-chained hydrocarbon isotopologues is possible.

Bubble Behaviour in Viscous Flows: Experimental and Numerical Determination of 3D-Trajectories

2006 ◽  
Author(s):  
Sylvain Chaminade ◽  
Jean Toutain ◽  
Stefan Dilhaire ◽  
Eric Arquis ◽  
Christine Marraud ◽  
...  
Keyword(s):  
Viscous Flows ◽  
Coupling Model ◽  
Light Sources ◽  
Visualization Method ◽  
Air Bubble ◽  
Video Cameras ◽  
Silicon Oil ◽  
Selection Of ◽  
Bubble Behaviour

We studied the air bubble behavhiour in viscous flows. A one-way coupling model was developed, based on lagrangian method. In order to validate this model, experiments were carried out. Our experimental installation was based on shadow visualization method. Bubbles were introduced in a transparent Plexiglas tank filling with viscous fluid (e.g. silicon oil) and were illuminated by diffused lights. In order to reconstruct 3D-trajectories, two video cameras, orthogonally placed, took pictures of shape bubbles and a post treatment of images acquired allowed us to determine the position of the center and the radius of each bubble. Thus, from this information of each plane, we could determine the 3D parameters of bubbles. Superluminescent LEDs with different wave-lengths were used as light sources. The choice of the wavelengths for each plane illumination and the selection of appropriated RGB filter of CCD sensor allowed us to prevent dissymmetry of bubble shape which was due to parasitic orthogonal illumination. Numerical results agree with experimental data.

DETERMINATION OF TRANSFER FUNCTIONS OF MCP-200 ALLOY USING 6 MV PHOTON BEAM FOR BEAM INTENSITY MODULATION

2004 ◽  
Vol 04 (03) ◽  
pp. 305-310 ◽  
Author(s):  
MUHAMMAD MAQBOOL
Keyword(s):  
Linear Accelerator ◽  
Transfer Functions ◽  
Theoretical Data ◽  
Intensity Modulation ◽  
Beam Intensity ◽  
Experimental Results ◽  
Photon Beam ◽  
Photographic Film ◽  
Optimum Dose

Transfer functions of MCP-200 alloy were determined for beam intensity modulation. 6 MV Photon beam, obtained from linear accelerator, is attenuated by blocks of MCP-200 alloy with different thicknesses placed at a distance of one meter from the source. The attenuated beam was allowed to fall on photographic film and optical densities were measured. Films were scanned and profiles were obtained for different thicknesses of the alloy and in the absence of any attenuator. Transfer functions were obtained theoretically as well as analytically by fitting the experimental results into theoretical data. The whole work was completed using optimum dose units and found to be 30 cGy.

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