Analysis of photoacoustic signal dependence on modulation frequency for YAG crystal doped with Cr+3

2001 ◽  
Author(s):  
Anna Sikorska
Keyword(s):  
Modulation Frequency ◽  
Photoacoustic Signal ◽  
Signal Dependence

Investigation of the photoacoustic signal dependence on laser power

2007 ◽  
Author(s):  
Jan Niemi ◽  
Torbjörn Löfqvist ◽  
Per Gren
Keyword(s):  
Laser Power ◽  
Photoacoustic Signal ◽  
Signal Dependence

STUDY OF THERMAL TRANSPORT PARAMETERS IN PbI2 SINGLE CRYSTAL USING A PHOTOACOUSTIC TECHNIQUE

2006 ◽  
Vol 20 (20) ◽  
pp. 1253-1260 ◽  
Author(s):  
D. S. AHLAWAT ◽  
D. MOHAN ◽  
S. K. GHOSHAL ◽  
R. D. SINGH ◽  
MEENAKSHI SHARMA
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Single Crystal ◽  
Characteristic Frequency ◽  
Modulation Frequency ◽  
Thermal Effusivity ◽  
Photoacoustic Signal ◽  
Photoacoustic Technique ◽  
Front Side ◽  
Transport Parameters

The present work discusses the study of the transport properties of the PbI 2 single crystal using an indigenously developed photoacoutistic spectrometer. The amplitude photoacoustic signal, being a function of the modulation frequency of the incident optical beam, has been measured by using the front-side detection configuration. The characteristic frequency (fc) of the single crystal has been found to be 55 Hz. The values of thermal diffusivity, thermal conductivity and thermal effusivity in the case of PbI 2 have been derived experimentally. Their values have been compared with the values reported in a case which studied other materials in the literature. Thermal diffusion lengths have also been calculated at different chopping frequencies from 15 Hz to 90 Hz.

Signal Dependence on Light Modulation Frequency in Optogalvanic Spectroscopy

1999 ◽  
Vol 53 (12) ◽  
pp. 1651-1653 ◽  
Author(s):  
D. A. Rusak ◽  
J. E. Anderson ◽  
R. A. Keller ◽  
C. W. Wilkerson ◽  
E. E. Kunhardt
Keyword(s):  
Modulation Frequency ◽  
Light Modulation ◽  
Optogalvanic Spectroscopy ◽  
Signal Dependence

scholarly journals Electro-acustic influence of the measuring system on the photoacoustic signal amplitude and phase in frequency domain

2016 ◽  
Vol 14 (1) ◽  
pp. 9-20 ◽  
Author(s):  
Sanja Aleksic ◽  
Dragana Markushev ◽  
Dragan Pantic ◽  
Mihajlo Rabasovic ◽  
Dragan Markushev ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Flicker Noise ◽  
Modulation Frequency ◽  
Signal Amplitude ◽  
Photoacoustic Signal ◽  
Measuring System ◽  
Coherent Noise ◽  
Characteristic Frequencies ◽  
Signal Distortions ◽  
Set Up

The paper discusses the most common impacts of the measuring system on the amplitude and phase of the photoacoustic signals in the frequency domain using the open-cell experimental set-up. The highest signal distortions are detected at the ends of the observed modulation frequency range from 20 Hz to 20 kHz. The attenuation of the signal is observed at lower frequencies, caused by the electronic filtering of the microphone and sound card, with characteristic frequencies of 15 Hz and 25 Hz. At higher frequencies, the dominant signal distortions are caused by the microphone acoustic filtering, having characteristic frequencies around 9 kHz and 15 kHz. It has been found that the microphone incoherent noise, the so called flicker noise, is negligibly small in comparison to the signal and does not affect the signal shape. However, a coherent noise originating from the power modulation system of the light source significantly affects the shape of the signal in the range greater than 10 kHz. The effects of the coherent noise and measuring system influence are eliminated completely using the relevant signal correction procedure targeting the photoacoustic signal generated by the sample.

scholarly journals Нелинейный фотоакустический отклик на механические напряжения вблизи отверстия в пластине из алюминиевого сплава Д16

2020 ◽  
Vol 46 (4) ◽  
pp. 22
Author(s):  
А.Л. Глазов ◽  
Н.Ф. Морозов ◽  
К.Л. Муратиков
Keyword(s):  
Aluminum Alloy ◽  
Laser Radiation ◽  
Thermal Effect ◽  
Modulation Frequency ◽  
Photoacoustic Signal ◽  
Theoretical Description ◽  
Mechanical Stresses ◽  
Electronic Subsystem ◽  
Sound Generation ◽  
Photoacoustic Effect

The features of the behavior of the photoacoustic signal depending on mechanical stresses near the hole in the plate made of aluminum alloy D16 are investigated. A new nonlinear photoacoustic effect was discovered, which consists in the appearance of a nonlinear component of the photoacoustic signal depending on mechanical stresses near the hole. This dependence is recorded in the signal at the modulation frequency of the laser radiation. A theoretical description of the discovered effect of sound generation by the thermoelastic mechanism in stressed metals is proposed basing on the consideration of the thermal effect of laser radiation on their electronic subsystem.

scholarly journals Photoacoustic Properties of Polypyrrole Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2457
Author(s):  
Peter Keša ◽  
Monika Paúrová ◽  
Michal Babič ◽  
Tomáš Heizer ◽  
Petr Matouš ◽  
...  
Keyword(s):  
Contrast Agent ◽  
Photoacoustic Imaging ◽  
Particle Surface ◽  
Photoacoustic Signal ◽  
Ammonium Persulphate ◽  
Coated Nanoparticles ◽  
Polypyrrole Nanoparticles ◽  
Signal Dependence

Photoacoustic imaging, an emerging modality, provides supplemental information to ultrasound imaging. We investigated the properties of polypyrrole nanoparticles, which considerably enhance contrast in photoacoustic images, in relation to the synthesis procedure and to their size. We prepared polypyrrole nanoparticles by water-based redox precipitation polymerization in the presence of ammonium persulphate (ratio nPy:nOxi 1:0.5, 1:1, 1:2, 1:3, 1:5) or iron(III) chloride (nPy:nOxi 1:2.3) acting as an oxidant. To stabilize growing nanoparticles, non-ionic polyvinylpyrrolidone was used. The nanoparticles were characterized and tested as a photoacoustic contrast agent in vitro on an imaging platform combining ultrasound and photoacoustic imaging. High photoacoustic signals were obtained with lower ratios of the oxidant (nPy:nAPS ≥ 1:2), which corresponded to higher number of conjugated bonds in the polymer. The increasing portion of oxidized structures probably shifted the absorption spectra towards shorter wavelengths. A strong photoacoustic signal dependence on the nanoparticle size was revealed; the signal linearly increased with particle surface. Coated nanoparticles were also tested in vivo on a mouse model. To conclude, polypyrrole nanoparticles represent a promising contrast agent for photoacoustic imaging. Variations in the preparation result in varying photoacoustic properties related to their structure and allow to optimize the nanoparticles for in vivo imaging.

The Absorption Behavior of Water and Some Organic Liquids in the Near Infrared Studied by Photoacoustic Spectroscopy

1984 ◽  
Vol 39 (12) ◽  
pp. 1242-1249 ◽  
Author(s):  
U. Haas ◽  
H. Seiler
Keyword(s):  
Photoacoustic Spectroscopy ◽  
Near Infrared ◽  
Modulation Frequency ◽  
Incident Light ◽  
Photoacoustic Signal ◽  
Liquid Structure ◽  
Organic Liquids ◽  
Absorption Bands ◽  
Expected Frequency ◽  
Hydroxyl Absorption

The optical absorption of water and some organic liquids [CH3OH, CH3OD, CD3OD, C2H5OH, C4H9OH, (CH3)2CO, (C2H5)2O and C6H6] has been investigated in the near infrared by photoacoustic spectroscopy. Characteristical absorption bands of combinations and overtones of strong infrared fundamental vibrations are observed and can be used for qualitative analysis of these liquids. The amplitude of the photoacoustic signal shows an f-1-dependence of the modulation frequency f of the incident light for all absorption signals, except for the hydroxyl absorption bands of water and the alcohols. The deviation of the expected frequency dependence points to a modification of the liquid structure toward the surface of the liquid-gas boundary.

scholarly journals Photoacoustic Measurement of Ethane with Near-Infrared DFB Diode Laser

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Gang Cheng ◽  
Yuan Cao ◽  
Kun Liu ◽  
Gongdong Zhu ◽  
Guishi Wang ◽  
...  
Keyword(s):  
Diode Laser ◽  
Near Infrared ◽  
Second Harmonic ◽  
Modulation Frequency ◽  
Photoacoustic Signal ◽  
Minimum Detectable Concentration ◽  
Modulation Amplitude ◽  
Excitation Light ◽  
Detection Scheme ◽  
Detectable Concentration

A compact resonant photoacoustic sensor based on a near-infrared distributed-feedback (DFB) diode laser was developed for detection of ethane (C2H6). A DFB laser emission at 5937.25 cm−1 with a power of ∼5 mW was used as an excitation light source for generating the photoacoustic signal. Wavelength modulation and second harmonic detection scheme were employed. Modulation frequency and modulation amplitude were optimized for getting optimum performance. Performance evaluation based on the linearity response of the PAS sensor system with respect to C2H6 concentration levels was performed, and a good linear dependence of the PAS signal on the C2H6 concentration was obtained. A minimum detectable concentration of 9 ppmv was achieved for detection of C2H6 with a lock-in time constant of 10 ms.

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