Tunable Light Source for Photoacoustic Sensing Applications

2018 ◽  
Author(s):  
A. Kovacs ◽  
S. Keshavarzi ◽  
A. O. Perez ◽  
S. Palzer ◽  
U. Mescheder
Keyword(s):  
Light Source ◽  
Sensing Applications

Simple multiwavelength time-division multiplexed light source for sensing applications

2008 ◽  
Vol 33 (7) ◽  
pp. 738 ◽  
Author(s):  
Thilo Kraetschmer ◽  
Daryl Dagel ◽  
Scott T. Sanders
Keyword(s):  
Light Source ◽  
Sensing Applications ◽  
Time Division

scholarly journals Investigation on optical integration between LED Mid-IR light sources and Si-based waveguides for sensing applications

2021 ◽  
Vol 2145 (1) ◽  
pp. 012056
Author(s):  
Pawaphat Jaturaphagorn ◽  
Papichaya Chaisakul ◽  
Nattaporn Chattham ◽  
Pichet Limsuwan
Keyword(s):  
Integrated Circuits ◽  
Light Source ◽  
Light Emitting Diode ◽  
Coupling Scheme ◽  
Light Sources ◽  
Optical Coupling ◽  
Led Light ◽  
Carbon Dioxide Gas ◽  
Sensing Applications ◽  
Ir Light

Abstract Research on mid-IR silicon-based waveguides has recently received strong interest. Particularly, this paper focuses on one of the critical issues in micron-scale photonic integrated circuits, which is to efficiently couple a mid-IR LED (light emitting diode) light source to an external micron-scale waveguide. The optical coupling scheme is crucial for the exploitation of LED light sources in waveguide-based spectroscopic sensing applications. This paper reports optical coupling scheme between an LED mid-IR light source and a silicon rich silicon nitride (SiN) waveguide that could enable the use of LED-based light sources. Finally, the detection limit of the investigated device for carbon dioxide gas detection is calculated.

scholarly journals Portable and Affordable Light Source-Based Photoacoustic Tomography

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6173
Author(s):  
Mithun Kuniyil Ajith Singh ◽  
Wenfeng Xia
Keyword(s):  
Light Source ◽  
Photoacoustic Imaging ◽  
Imaging Modality ◽  
Clinical Translation ◽  
Photoacoustic Tomography ◽  
Light Sources ◽  
Excitation Light ◽  
Sensing Applications ◽  
Wide Range ◽  
Technological Developments

Photoacoustic imaging is a hybrid imaging modality that offers the advantages of optical (spectroscopic contrast) and ultrasound imaging (scalable spatial resolution and imaging depth). This promising modality has shown excellent potential in a wide range of preclinical and clinical imaging and sensing applications. Even though photoacoustic imaging technology has matured in research settings, its clinical translation is not happening at the expected pace. One of the main reasons for this is the requirement of bulky and expensive pulsed lasers for excitation. To accelerate the clinical translation of photoacoustic imaging and explore its potential in resource-limited settings, it is of paramount importance to develop portable and affordable light sources that can be used as the excitation light source. In this review, we focus on the following aspects: (1) the basic theory of photoacoustic imaging; (2) inexpensive light sources and different implementations; and (3) important preclinical and clinical applications, demonstrated using affordable light source-based photoacoustics. The main focus will be on laser diodes and light-emitting diodes as they have demonstrated promise in photoacoustic tomography—the key technological developments in these areas will be thoroughly reviewed. We believe that this review will be a useful opus for both the beginners and experts in the field of biomedical photoacoustic imaging.

Two MOEMS Microphone Designs for Acoustic Sensing Applications

2005 ◽  
Vol 883 ◽  
Author(s):  
Berit S. Avset ◽  
Kari A. H. Bakke ◽  
Britta. G. Fismen ◽  
Ib-Rune Johansen ◽  
Henrik Rogne ◽  
...  
Keyword(s):  
Light Source ◽  
Low Cost ◽  
Ring Structure ◽  
Air Gap ◽  
The Other ◽  
Diffractive Lens ◽  
Measured Intensity ◽  
Sensing Applications ◽  
Fabry Perot ◽  
Metallic Ring

AbstractTwo different micro-optical microphones are presented. The first is based on interferometric read-out of a deflecting membrane, based on the Fabry-Perot principle. The sensing device is produced in Silicon by combining standard CMOS and MEMS processing. This ensures that high accuracy alignment and low cost production can be obtained. Optical sensor elements with a ring structure are included on one of the Fabry-Perot surfaces whereas the other surface is an optically transparent membrane. Light from an uncollimated light source such as a semiconductor laser or a LED, will form a ring pattern when transmitted through the membrane.The other microphone principle presented is based on a diffractive lens. The structure has a metallic ring pattern separated from a reflecting membrane with an air gap. When the air gap is an odd number of quarter wavelengths of the impinging light, these surfaces form a binary phase diffractive lens. By placing a light source and a detector in the focal plane of the lens, the measured intensity will be highly sensitive to the position of the membrane. Similarly to the first microphone this device can be mass produced at low cost using micromachining techniques.Results from prototype devices will be presented, proving both principles and showing excellent properties compared to expensive commercially available condenser microphones.

scholarly journals Broadband mid-infrared amplified spontaneous emission from Er/Dy co-doped fluoride fiber with a simple diode-pumped configuration

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kenji Goya ◽  
Akira Mori ◽  
Shigeki Tokita ◽  
Ryo Yasuhara ◽  
Tetsuo Kishi ◽  
...  
Keyword(s):  
Light Source ◽  
Spontaneous Emission ◽  
Gas Sensing ◽  
Amplified Spontaneous Emission ◽  
Ion Concentration ◽  
Light Sources ◽  
Multimode Laser ◽  
Mid Infrared ◽  
Sensing Applications ◽  
Co Doped

AbstractEr3+/Dy3+ co-doped double-clad ZBLAN optical fiber has been used to obtain amplified spontaneous emission (ASE) broadband light sources cladding-pumped by 980-nm multimode laser diode (LD) sources. It has been demonstrated that mid-infrared broadband emission extending from 2515 to 3735 nm was obtained by energy transfer between Er3+ and Dy3+. We experimentally investigated the optimum design of Er3+/Dy3+ co-doped ZBLAN fiber in terms of ion concentration, fiber length, pumping configuration, and pumping power. The ASE output power was more than 2.5 mW when the LD pump power was set at 5 W. To assess its potential for gas sensing applications, the fabricated ASE light source was used to successfully detect methane gas with concentrations at 1% and 5%. The simple and stable construction of our ASE light source is suitable for practical purposes.

A Method for Setting the Clearance Angle

1972 ◽  
Vol 30 ◽  
pp. 388-389
Author(s):  
Michael T. Bucek ◽  
Howard J. Arnott
Keyword(s):  
Experimental Evidence ◽  
Light Source ◽  
Black Spot ◽  
Critical Factor ◽  
Clearance Angle ◽  
Crude Approximation ◽  
Ultrathin Sections

It is believed by the authors, with supporting experimental evidence, that as little as 0.5°, or less, knife clearance angle may be a critical factor in obtaining optimum quality ultrathin sections. The degree increments located on the knife holder provides the investigator with only a crude approximation of the angle at which the holder is set. With the increments displayed on the holder one cannot set the clearance angle precisely and reproducibly. The ability to routinely set this angle precisely and without difficulty would obviously be of great assistance to the operator. A device has been contrived to aid the investigator in precisely setting the clearance angle. This device is relatively simple and is easily constructed. It consists of a light source and an optically flat, front surfaced mirror with a minute black spot in the center. The mirror is affixed to the knife by placing it permanently on top of the knife holder.

A confocal laser scanning microscope for fluorescence and reflection at video rates

1989 ◽  
Vol 47 ◽  
pp. 134-135
Author(s):  
P.M. Houpt ◽  
A. Draaijer
Keyword(s):  
Light Source ◽  
Laser Scanning ◽  
Focal Point ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Point Light Source ◽  
Volume Of Interest ◽  
Ion Laser ◽  
Point Light ◽  
Point Detector

In confocal microscopy, the object is scanned by the coinciding focal points (confocal) of a point light source and a point detector both focused on a certain plane in the object. Only light coming from the focal point is detected and, even more important, out-of-focus light is rejected.This makes it possible to slice up optically the ‘volume of interest’ in the object by moving it axially while scanning the focused point light source (X-Y) laterally. The successive confocal sections can be stored in a computer and used to reconstruct the object in a 3D image display.The instrument described is able to scan the object laterally with an Ar ion laser (488 nm) at video rates. The image of one confocal section of an object can be displayed within 40 milliseconds (1000 х 1000 pixels). The time to record the total information within the ‘volume of interest’ normally depends on the number of slices needed to cover it, but rarely exceeds a few seconds.

Inter-Method Reliability of Pulse Volume Related Measures Derived Using Finger-Photoplethysmography

2018 ◽  
Vol 32 (4) ◽  
pp. 182-190 ◽  
Author(s):  
Kenta Matsumura ◽  
Koichi Shimizu ◽  
Peter Rolfe ◽  
Masanori Kakimoto ◽  
Takehiro Yamakoshi
Keyword(s):  
Light Intensity ◽  
Adverse Effects ◽  
Light Source ◽  
Direct Current ◽  
Resting State ◽  
Current Component ◽  
Psychophysiological Measures ◽  
Pulse Volume ◽  
Optical Paths ◽  
Sensor Positions

Abstract. Pulse volume (PV) and its related measures, such as modified normalized pulse volume (mNPV), direct-current component (DC), and pulse rate (PR), derived from the finger-photoplethysmogram (FPPG), are useful psychophysiological measures. Although considerable uncertainties exist in finger-photoplethysmography, little is known about the extent of the adverse effects on the measures. In this study, we therefore examined the inter-method reliability of each index across sensor positions and light intensities, which are major disturbance factors of FPPG. From the tips of the index fingers of 12 participants in a resting state, three simultaneous FPPGs having overlapping optical paths were recorded, with their light intensity being changed in three steps. The analysis revealed that the minimum values of three coefficients of Cronbach’s α for ln PV, ln mNPV, ln DC, and PR across positions were .948, .850, .922, and 1.000, respectively, and that those across intensities were .774, .985, .485, and .998, respectively. These findings suggest that ln mNPV and PR can be used for psychophysiological studies irrespective of minor differences in sensor attachment positions and light source intensity, whereas and ln DC can also be used for such studies but under the condition of light intensity being fixed.

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