Laser schlieren microphone for optoacoustic spectroscopy

J. G. Choi, G. J. Diebold

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

This paper describes a laser schlieren microphone, where a low-power He-Ne laser beam is deflected by a reflecting diaphragm mounted on an optoacoustic Helmholtz resonator. The sinusoidal pressure variations in the resonator distort the surface of the diaphragm so that the reflected laser beam is alternately focused and defocused. The deflection is converted into an amplitude modulation of the beam by an iris located at a distance from the resonator and detected with a photodiode. The light beam can be modulated at a high frequency and the signal from the photodiode processed with a lock-in amplifier so that noise with a power spectral density proportional to the inverse of the frequency is significantly reduced in the final optoacoustic signal. A mathematical description of the laser schlieren microphone is given that shows the system to respond linearly to small signals. An experiment was done to determine the range of linear response of the microphone to large amplitude optoacoustic signals.

Original languageEnglish
Pages (from-to)4087-4091
Number of pages5
JournalApplied Optics
Volume21
Issue number22
DOIs
Publication statusPublished - 1982 Nov 15

Fingerprint

Photoacoustic spectroscopy
Photoacoustic effect
Microphones
microphones
Resonators
Diaphragms
Photodiodes
Laser beams
Lasers
diaphragms
spectroscopy
lasers
photodiodes
Amplitude modulation
resonators
Power spectral density
laser beams
Helmholtz resonators
light beams
deflection

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

Cite this

Choi, J. G. ; Diebold, G. J. / Laser schlieren microphone for optoacoustic spectroscopy. In: Applied Optics. 1982 ; Vol. 21, No. 22. pp. 4087-4091.
@article{67501019abca420c95c62c1326eb95ed,
title = "Laser schlieren microphone for optoacoustic spectroscopy",
abstract = "This paper describes a laser schlieren microphone, where a low-power He-Ne laser beam is deflected by a reflecting diaphragm mounted on an optoacoustic Helmholtz resonator. The sinusoidal pressure variations in the resonator distort the surface of the diaphragm so that the reflected laser beam is alternately focused and defocused. The deflection is converted into an amplitude modulation of the beam by an iris located at a distance from the resonator and detected with a photodiode. The light beam can be modulated at a high frequency and the signal from the photodiode processed with a lock-in amplifier so that noise with a power spectral density proportional to the inverse of the frequency is significantly reduced in the final optoacoustic signal. A mathematical description of the laser schlieren microphone is given that shows the system to respond linearly to small signals. An experiment was done to determine the range of linear response of the microphone to large amplitude optoacoustic signals.",
author = "Choi, {J. G.} and Diebold, {G. J.}",
year = "1982",
month = "11",
day = "15",
doi = "10.1364/AO.21.004087",
language = "English",
volume = "21",
pages = "4087--4091",
journal = "Applied Optics",
issn = "1559-128X",
publisher = "The Optical Society",
number = "22",

}

Laser schlieren microphone for optoacoustic spectroscopy. / Choi, J. G.; Diebold, G. J.

In: Applied Optics, Vol. 21, No. 22, 15.11.1982, p. 4087-4091.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Laser schlieren microphone for optoacoustic spectroscopy

AU - Choi, J. G.

AU - Diebold, G. J.

PY - 1982/11/15

Y1 - 1982/11/15

N2 - This paper describes a laser schlieren microphone, where a low-power He-Ne laser beam is deflected by a reflecting diaphragm mounted on an optoacoustic Helmholtz resonator. The sinusoidal pressure variations in the resonator distort the surface of the diaphragm so that the reflected laser beam is alternately focused and defocused. The deflection is converted into an amplitude modulation of the beam by an iris located at a distance from the resonator and detected with a photodiode. The light beam can be modulated at a high frequency and the signal from the photodiode processed with a lock-in amplifier so that noise with a power spectral density proportional to the inverse of the frequency is significantly reduced in the final optoacoustic signal. A mathematical description of the laser schlieren microphone is given that shows the system to respond linearly to small signals. An experiment was done to determine the range of linear response of the microphone to large amplitude optoacoustic signals.

AB - This paper describes a laser schlieren microphone, where a low-power He-Ne laser beam is deflected by a reflecting diaphragm mounted on an optoacoustic Helmholtz resonator. The sinusoidal pressure variations in the resonator distort the surface of the diaphragm so that the reflected laser beam is alternately focused and defocused. The deflection is converted into an amplitude modulation of the beam by an iris located at a distance from the resonator and detected with a photodiode. The light beam can be modulated at a high frequency and the signal from the photodiode processed with a lock-in amplifier so that noise with a power spectral density proportional to the inverse of the frequency is significantly reduced in the final optoacoustic signal. A mathematical description of the laser schlieren microphone is given that shows the system to respond linearly to small signals. An experiment was done to determine the range of linear response of the microphone to large amplitude optoacoustic signals.

UR - http://www.scopus.com/inward/record.url?scp=0020208786&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0020208786&partnerID=8YFLogxK

U2 - 10.1364/AO.21.004087

DO - 10.1364/AO.21.004087

M3 - Article

C2 - 20401014

AN - SCOPUS:0020208786

VL - 21

SP - 4087

EP - 4091

JO - Applied Optics

JF - Applied Optics

SN - 1559-128X

IS - 22

ER -