Applications of an optical parametric system in opto-acoustic experiments
Applications of an optical parametric system in opto-acoustic experiments
An account is given of experiments in opto-acoustic (or photo-acoustic) spectroscopy which utilised a source of pulsed laser radiation, a computer controlled optical parametric oscillator (OPO). This device provided continuously tunable radiation in the range 2.12 to 1. 42/µm (signal output) and 2.12 to 4.2µm (idler output). Pulse energies approaching 20 ml in 10 ns were achieved during the work described here. The tuning range could be extended to 25nm by frequency mixing the two output waves in a non-linear crystal. A successful demonstration of a new technique for Raman spectroscopy is reported. Gas molecules that were Raman-excited by two laser beams were detected by the opto-acoustic effect. The OPO provided the two beams ; their necessary coincidence was thus ensured. Initial experiments produced spectra of the 775 cm-1 Raman transition of SF6 gas at atmospheric pressure. The design and performance of an opto-acoustic cell used for this work are discussed. The lowest absorption detected was 2 x 10-9J ml per laser pulse. Possible factors which limited the performance, and therefore the sensitivities of both the Raman and single photon absorption spectroscopy are identified. Another application reported here was in the spectroscopy of gases at high temperatures (>1000°C). The development of a method for remotely detecting opto-acoustic signals, which used a visible laser beam as a probe, is described. Other work discussed includes the opto-acoustic spectroscopy of gas in a flame and molecular fluorescence experiments. A theoretical description of the opto-acoustic effect in gases, for pulsed laser excitation, is also presented. This attempts to cover the process from the absorption of radiation to the resulting acoustic signal in a gas cell.
University of Southampton
Tupper, Graham David
23d334c6-4939-4481-9f46-0c89d6736c85
1983
Tupper, Graham David
23d334c6-4939-4481-9f46-0c89d6736c85
Tupper, Graham David
(1983)
Applications of an optical parametric system in opto-acoustic experiments.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
An account is given of experiments in opto-acoustic (or photo-acoustic) spectroscopy which utilised a source of pulsed laser radiation, a computer controlled optical parametric oscillator (OPO). This device provided continuously tunable radiation in the range 2.12 to 1. 42/µm (signal output) and 2.12 to 4.2µm (idler output). Pulse energies approaching 20 ml in 10 ns were achieved during the work described here. The tuning range could be extended to 25nm by frequency mixing the two output waves in a non-linear crystal. A successful demonstration of a new technique for Raman spectroscopy is reported. Gas molecules that were Raman-excited by two laser beams were detected by the opto-acoustic effect. The OPO provided the two beams ; their necessary coincidence was thus ensured. Initial experiments produced spectra of the 775 cm-1 Raman transition of SF6 gas at atmospheric pressure. The design and performance of an opto-acoustic cell used for this work are discussed. The lowest absorption detected was 2 x 10-9J ml per laser pulse. Possible factors which limited the performance, and therefore the sensitivities of both the Raman and single photon absorption spectroscopy are identified. Another application reported here was in the spectroscopy of gases at high temperatures (>1000°C). The development of a method for remotely detecting opto-acoustic signals, which used a visible laser beam as a probe, is described. Other work discussed includes the opto-acoustic spectroscopy of gas in a flame and molecular fluorescence experiments. A theoretical description of the opto-acoustic effect in gases, for pulsed laser excitation, is also presented. This attempts to cover the process from the absorption of radiation to the resulting acoustic signal in a gas cell.
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Published date: 1983
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Local EPrints ID: 459434
URI: http://eprints.soton.ac.uk/id/eprint/459434
PURE UUID: d0f5b4df-d40d-4b96-986f-0e4c369826e6
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Date deposited: 04 Jul 2022 17:10
Last modified: 11 May 2023 17:06
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Author:
Graham David Tupper
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