Absorption of pulsed laser radiation by a single particle generates a photoacoustic wave whose time profile can be measured with a wideband pressure transducer. Solution of the wave equation for pressure in one, two, and three dimensions shows that the photoacoustic wave is determined by the geometry and dimensions of the particle, and by its sound speed and density relative to the fluid that surrounds it. Photoacoustic waves, referred to here as signatures, are reported in experiments in which fluid droplets, cylinders, and layers are irradiated with 10-nanosecond laser pulses.

http://science.sciencemag.org/content/sci/250/4977/101.full.pdf

Photoacoustic "signatures" of particulate matter: optical production of acoustic monopole radiation.

Introduction Photoacoustic (sometimes called optoacoustic) and photothermal methods measure the heat emitted by radiationless processes deactivating excited species. These methods are complementary to other photophysical and photochemical methods and most of them have the advantage of being applicable also to non-transparent and to highly scattering media. The basis of photoacoustic spectroscopy (PAS) and its applications have been extensively reviewed (Brisset, 1983; Pao, 1977; Rosencwaig, 1980; Tam, 1983) as well as the uses in biology (Cahen et al., 1980; Moore, 1983). Selected examples of the applications of PAS to biology have been presented by Balasubramanian and Rao (1981, 1986). I also refer the reader to communications on the subject presented at the Third International Conference on Photoacoustic and Photothermal Spectroscopy, Paris, France, 1983 (Biichner et al., 1983; Carpentier et al., 1983; Giese and Kolmel, 1983; Jabben et al . , 1983; Kirkbright et al. , 1983; Moore et al . , 1983; Poulet and Chambron, 1983; Renard and Delmelle, 1983; Veeranjaneyulu and Das, 1983; Xiao etal., 1983) and to those presented at the Fourth lnternational Topical Meeting on Photoacoustic, Thermal, and related Sciences, Ville d’Esterel, Quebec, Canada, 1985 (Boucher and Leblanc, 1985; Buschmann and Prehn, 1985; Canaani and Malkin, 1985; Canaani et al., 1985a and c; Carpentier et al. , 1985a; Desormeaux and Leblanc, 1985; Larue e ta l . , 1985; Malkin, 1985; Nicolaus et a[ . , 1985; Pessoa et al . , 1985; Upadhyaya, 1985). This review briefly summarizes the reports on PAS applied to biological samples, especially those published in the last two years. It focuses mainly on the question of the time profile of the heat emission after electronic excitation. In general, instrumentation problems and analytical applications will not be dealt with in depth, apart from some novel contributions. Since the photoacoustic spectrum is essentially the action spectrum of the heat emitted by the sample after the absorption of light (Moore, 1983), the data can be used to determine the energy content of the heat emitting species (vide infra). The knowledge of the heat-time profile permits the eventual determination of lifetime and energy content of short-lived species formed in the course of a reaction, as well as the quantum yield of their production. The techniques also provide information on the thermoelastic properties of the medium. The latter aspect, however, will also be omitted from this review, Two modes can be used for the excitation of the sample. One of them utilizes an intensity-modulated continuous wave (conventional or laser) source, and phase sensitive detection. For the detection of the heat release different transducers may be used. PAS detects the thermally induced pressure wave by means of a gas coupled microphone. Photorefractive techniques detect the induced change of refractive index above or within the sample. If the exciting source is a laser beam, this sensing can be accomplished by observing the changes which the thermal lens induces upon the focus of the excitation beam (thermal-lensing or thermal-blooming) (Fang and Swofford, 1983; Whinnery, 1974). A probe laser beam can also be used to detect the refractive index changes. The general principles of the photorefractive techniques and their applications to absorption measurements have been reviewed by Fang and Swofford (1983). Boccara et al. (1980) and Jackson et al. (1981) have described the collinear and transverse arrangement of the excitation and probe beams and have compared the acoustic and beam deflection detection techniques. An IR detector has been used to detect the heat deposited in the sample (Nordal and Kanstad, 1979). This alternative has been called photothermal detection. In the other mode a pulse of light (normally a pulsed laser) excites the sample. The heat emitted is detected either with a piezoelectric transducer via the acoustic pulse generated (Pate1 and Tam, 1981), with a probe laser beam (Fuke et al . , 1983; Mori et al., 1982; Rossbroich et al . , 1985), or with an infrared detector (Tam, 1985).

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1751-1097.1986.tb05645.x

Photo acoustic and photothermal methods applied to the study of radiationless deactivation processes in biological systems and in substances of biological interest

Generating underwater acoustic signals from a remote, aerial location by use of a high-energy pulsed infrared laser has been demonstrated. The laser beam is directed from the air and focused onto the water surface, where the optical energy was converted into a propagating acoustic wave. Sound pressure levels of 185 dB re microPa (decibel re microPa) were consistently recorded under freshwater laboratory conditions at laser-pulse repetition rates of up to 1000 pulses/s. The nonlinear optoacoustic transmission concept is outlined, and the experimental results from investigation of the time-domain and frequency-domain characteristics of the generated underwater sound are provided. A high repetition rate, high-energy per pulse laser was used in this test under freshwater laboratory conditions. A means of deterministically controlling the spectrum of the underwater acoustic signal was investigated and demonstrated by varying the laser-pulse repetition rate.

Experimental demonstration of multiple pulse nonlinear optoacoustic signal generation and control

A remote, aerial, laser-based sonar and communications concept has been demonstrated to direct laser beams from the air onto the water surface to remotely generate and detect underwater sound. This forms the basis for a portable, aerial sonar and communications system for both detecting underwater objects such as vehicles and mines as well as for bi-directional acoustic communication between an in-air platform and a submerged platform operating at speed and depth. Two laser systems are required. The first laser system is a high-energy laser, the opto-acoustic transmitter, whose optical energy is converted to acoustic energy at the water surface. The second laser system is a laser interferometer, the acousto-optic sensor that detects underwater sound by measuring the vibrations of the water surface caused by the incident underwater sound field. Historically, acoustic transmitters and detectors need to be submerged to interact with the underwater environment. This remote, aerial, laser-based sonar and communication system presents a revolutionary change in the way sonar and communications can be realized, by remotely activating and detecting underwater acoustics from the air.

Remote, aerial, opto-acoustic communications and sonar

Generation of ultrasonic displacements under the thermoelastic effect has the advantage of being contactless and nondestructive. Unfortunately, the directivity and energy of the sound field of such a source are limited. In order to change these parameters the authors use a moving thermoelastic source by moving the laser beam on the solid surface. Moving the laser beam allows control of the ultrasonic beam directivity and an increase in the energy of the sound field. For this purpose, a large impulse of dye laser deflected by an acoustooptic cell working under the Bragg mode is used. Experimental results, in an aluminum sample give good agreement with the theoretical prediction. >

Directivity patterns of a moving thermoelastic source in solid media

Optical generation of sound in a liquid - Thermal mechanism /Review/

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

L. M. Liamshev

Author Tools

Chat about Author

Papers

Optical generation of sound in a liquid - Thermal mechanism /Review/