scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Multiple‐pass laser beam deflection probe for detection of acoustic and weak shock waves in fluids

01 Sep 1995-Review of Scientific Instruments (American Institute of Physics)-Vol. 66, Iss: 9, pp 4644-4648
TL;DR: In this article, the authors examined a laser beam deflection arrangement for detection of acoustic and weak shock waves in fluids, where the probe beam passes the wave propagation region several times before it reaches the deflectiondetecting photodetector.
Abstract: We examine a novel laser beam deflection arrangement for detection of acoustic and weak shock waves in fluids. Novelty of the arrangement is folding of the probe beam by two parallel plane mirrors in such a way that the probe beam passes the wave propagation region several times before it reaches the deflection‐detecting photodetector. In this way the probed wave interacts with several segments of the probing beam in sequence. A single oscilloscope trace of the photodetector output thus gives us the possibility to study the evolution of the probed wave at several distances from the source. To demonstrate the potentials of the arrangement we present wave forms of spherical blast waves detected in air during laser ablation of solid samples. We also discuss a simple theoretical model that qualitatively explains the most characteristic features of this arrangement.
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, the authors used an optical probe based on deflections of a laser beam to measure the cavitation bubble and the shock wave in distilled water by a Nd:YAG pulsed laser.
Abstract: High-intensity light from a laser pulse can produce optical breakdown in a liquid, followed by a shock wave and the growth of a cavitation bubble. When the bubble reaches its maximum radius the liquid pressure causes it to collapse, which in turn initiates the growth of another bubble. The oscillations can repeat themselves several times, and a shock wave is emitted after every collapse. In our study the breakdown was induced in distilled water by a Nd:YAG pulsed laser, which was designed for ocular photodisruption. The main focus of our experiments was measurement of the cavitation bubble and the shock waves using an optical probe based on deflections of a laser beam. The applied experimental setup made it possible to carry out one- or two-dimensional scanning of the cavitation bubble based on automatic control of the experiment. Since the beam-deflection probe (BDP) allowed simultaneous measurements of the cavitation bubble and the shock waves, we developed a method for reducing the measurement noise of...

94 citations

01 Jan 1990
TL;DR: In this paper, the beam deflection signal due to an acoustic wave and a thermal wave are both distorted as the excimer laser beam fluence is raised through the ablation threshold.
Abstract: Probe beam deflection is used for identification of the laser fluence threshold for excimer laser photoablation of various materials. The beam deflection signal due to an acoustic wave and a thermal wave are both distorted as the excimer laser beam fluence is raised through the ablation threshold.

75 citations

Journal ArticleDOI
TL;DR: In this paper, the cavitation bubble's oscillations and the corresponding shock waves were measured from the deflections of a laser beam using a fast quadrant photodiode, built into the optical probe.
Abstract: High-intensity light from a laser pulse can produce laser-induced breakdown in a liquid followed by a shock wave and the growth of a cavitation bubble. When the bubble reaches its maximum radius, the pressure of the surrounding liquid causes it to collapse; this results in bubble oscillations. The cavitation bubble's oscillations and the corresponding shock waves were measured from the deflections of a laser beam. These deflections were detected using a fast quadrant photodiode, built into the optical probe. The precise relative-positioning system and the small diameter of the beam's waist made it possible to detect and analyse the signals from the shock wave and the cavitation bubble. Here, we have demonstrated that a method based on a beam-deflection probe can be used to measure the fast phenomena that follow immediately after laser-induced breakdown as well as the whole dynamics of the bubble oscillations, which corresponds to a three-orders-of-magnitude larger time scale.

39 citations

Journal ArticleDOI
TL;DR: In this paper, a gas-coupled laser acoustic detection (GCLAD) was used to detect surface-acoustic wave forms in graphite/polymer composite panels.
Abstract: Airborne acoustic waves have been detected by a laser-beam deflection technique in both the ultrasonic and audio frequency ranges. For ultrasonic applications, a probe beam is directed parallel to the surface of a sample. Ultrasonic waves in the solid are detected when an acoustic wave is radiated from the surface into the ambient air, where the density variations cause a beam deflection. Gas-coupled laser acoustic detection (GCLAD) has been used to record well-resolved through-transmission and surface-acoustic wave forms in various materials. GCLAD has also been incorporated into a C-scanning system where it has been used to image subsurface flaws in graphite/polymer composite panels. Because the laser beam is not reflected from the sample surface, the technique is not dependent upon the surface optical properties of the material under investigation. It is particularly useful for testing graphite/polymer composites and other materials with rough surfaces. The beam-deflection technique has been tested qua...

25 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used laser probe beam and multiple-pass deflection techniques for real-time and in situ monitoring of laser ablation plasma plumes in the mTorr pressure regime.

19 citations

References
More filters
Journal ArticleDOI
Andrew C. Tam1
TL;DR: In this article, the theory and applications of photo-acoustic (also called optoacoustic) methods belonging to the more general area of photothermal measurement techniques are reviewed, covering excitation of gaseous or condensed samples with modulated continuous light beams or pulsed light beams.
Abstract: This paper reviews the theory and applications of photoacoustic (also called optoacoustic) methods belonging to the more general area of photothermal measurement techniques. The theory covers excitation of gaseous or condensed samples with modulated continuous light beams or pulsed light beams. The applications of photoacoustic methods include spectroscopy, monitoring deexcitation processes, probing physical properties of materials, and generating mechanical motions. Several other related photothermal methods, as well as particle-acoustics and wave-acoustics methods are also described. This review complements an earlier and narrower review [Rev. Mod. Phys. 53, 517 (1981)] that is mainly concerned with sensitive detection by pulsed photoacoustic spectroscopy in condensed matter.

1,183 citations

Journal ArticleDOI
TL;DR: In this article, the effects of photoacoustic spectroscopy (PAS) in gaseous media are reviewed and a simple experimental method for the determination of Beyer's nonlinearity parameter B/A is presented.
Abstract: The laser generation of sound in liquids and gases is reviewed. The sound‐generating mechanisms of laser interaction with matter are discussed with emphasis on the thermoelastic process. The studies on strongly absorbing liquids include detailed theoretical considerations of the thermoelastic sound generation with pulsed lasers. Acoustic waveforms for H2O and D2O are calculated analytically on the basis of a model laser‐pulse shape. Both free and rigid boundaries on the surface of the liquid are considered. Good agreement between theory and experiments with respect to waveforms and amplitudes is obtained. The experiments are performed with a hybrid CO2 laser and piezoelectric or optical detection of the acoustic transients. In view of a present controversy, special emphasis is put on the temperature dependence of the acoustic amplitudes in H2O, D2O, and in aqueous MgSO4 solutions. Good agreement is found between experimental data and a new, pure thermal model which takes heat conduction into account. The distortion of the acoustic waveform during the propagation through the liquid is treated in terms of sound absorption, diffraction, and nonlinear acoustics. A simple experimental method for the determination of Beyer’s nonlinearity parameter B/A is presented. In the last section some characteristics of photoacoustic spectroscopy (PAS) in gaseous media are reviewed. This method has been demonstrated to be highly sensitive. The measurement of absorption coefficients as low as 10− 8 cm− 1 is possible. PA studies on H2O vapor are discussed with new results on line and continuum absorption in the 9–11‐μm wavelength range. Finally, the impact of PAS on trace gas analysis is demonstrated. With PAS the detection of gas concentrations in the ppb range is feasible. The operational characteristics of a stationary CO laser and a mobile CO2 laser‐PAS system are presented, including first results on continuous i n s i t u air pollution monitoring.

365 citations

01 Jan 1990
TL;DR: In this paper, the beam deflection signal due to an acoustic wave and a thermal wave are both distorted as the excimer laser beam fluence is raised through the ablation threshold.
Abstract: Probe beam deflection is used for identification of the laser fluence threshold for excimer laser photoablation of various materials. The beam deflection signal due to an acoustic wave and a thermal wave are both distorted as the excimer laser beam fluence is raised through the ablation threshold.

75 citations

Journal ArticleDOI
TL;DR: In this article, the beam deflection signal due to an acoustic wave and a thermal wave are both distorted as the excimer laser beam fluence is raised through the ablation threshold.
Abstract: Probe beam deflection is used for identification of the laser fluence threshold for excimer laser photoablation of various materials. The beam deflection signal due to an acoustic wave and a thermal wave are both distorted as the excimer laser beam fluence is raised through the ablation threshold.

73 citations

Journal ArticleDOI
TL;DR: In this paper, a laser deflection measurement system was developed which is both fast (τ≊20 ns) and sensitive (δφ≊0.5 μrad).
Abstract: A laser deflection measurement system has been developed which is both fast (τ≊20 ns) and sensitive (δφ≊0.5 μrad). This diagnostic is capable of sensing and discriminating between electrons and neutral particles in a multicomponent plasma, and yields quantitative results. The technique allows continuous measurements in time. Construction is inexpensive and simple to field. This system is, therefore, highly competitive with traditional techniques in diagnosing the development of transient plasmas.

57 citations