US 7,002,169 B2Granted

Method for generating photons by sonoluminescence

AssigneeCentre National de la Recherche Scientific (CNRS)

InventorsJean-Louis Thomas, Mathias Fink

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Abstract

A method of generating photons by sonoluminescence, from a gas bubble trapped in a liquid reservoir (2) by a standing ultrasound wave. An ultrasound impulse emitted by high-frequency transducers (T1–T8) is superposed on the standing wave, the high-frequency transducers being pre-focused onto the gas bubble and pre-synchronized with the light emissions from the gas bubble during an initial training stage in which said focusing and said synchronization are optimized.

Claims13

Dependent claims

A method of generating photons by sonoluminescence, said method comprising at least the following steps:

(a) generating at least one standing acoustic wave (S1) in a liquid reservoir (2), said standing acoustic wave having at least one antinode;
(b) trapping at least one gas bubble (5) in the liquid at said antinode of the standing acoustic wave, said gas bubble then being subjected to a periodic deformation cycle comprising expansion stages (10) and contraction stages (12) in alternation;
and
(e) generating acoustic wave impulses (S2) in the liquid, which compression acoustic wave impulse are superposed on the standing acoustic wave (S1), and cause photons to be emitted by the gas bubble, by sonoluminescence;
said method being characterized in that the acoustic wave impulses (S2) are caused to be emitted by a number n at least equal to 2 of impulse firing transducers (T1–T8) disposed around the gas bubble (5);
in that a focusing training step (c) and a synchronization step (d) 0 are interposed between the steps (b) and (e);
and
in that, during the focusing training step (c), the impulse firing transducers are caused to emit acoustic wave impulses (S2) with a first amplitude that is sufficiently small to avoid disturbing significantly the position and the deformation cycle of the gas bubble (5), acoustic signals generated by said acoustic wave impulse in the liquid reservoir are measured, and time offsets are deduced therefrom to be applied to respective (T1–T8) so as to focus said acoustic wave impulses onto the gas bubble (5);
in that, during the step (d), instants at which acoustic wave impulses (S2) are emitted by the various impulse firing transducers (T1–T8) are determined so that each wave impulse (2) generated by the impulse firing transducers reaches the gas bubble (5) either during a contraction stage if the wave impulse is compression wave, or during an expansion stage if the wave impulse is an expansion wave;
and
in that, during the step (e), the impulse firing transducers (T1–T8) are caused to generate the acoustic wave impulses at the respective emit instants determined at the step (d), with a second amplitude that is large than the first amplitude.

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Abstract

A method of generating photons by sonoluminescence, said method comprising at least the following steps:

(a) generating at least one standing acoustic wave (S1) in a liquid reservoir (2), said standing acoustic wave having at least one antinode;
(b) trapping at least one gas bubble (5) in the liquid at said antinode of the standing acoustic wave, said gas bubble then being subjected to a periodic deformation cycle comprising expansion stages (10) and contraction stages (12) in alternation;
and
(e) generating acoustic wave impulses (S2) in the liquid, which compression acoustic wave impulse are superposed on the standing acoustic wave (S1), and cause photons to be emitted by the gas bubble, by sonoluminescence;
said method being characterized in that the acoustic wave impulses (S2) are caused to be emitted by a number n at least equal to 2 of impulse firing transducers (T1–T8) disposed around the gas bubble (5);
in that a focusing training step (c) and a synchronization step (d) 0 are interposed between the steps (b) and (e);
and
in that, during the focusing training step (c), the impulse firing transducers are caused to emit acoustic wave impulses (S2) with a first amplitude that is sufficiently small to avoid disturbing significantly the position and the deformation cycle of the gas bubble (5), acoustic signals generated by said acoustic wave impulse in the liquid reservoir are measured, and time offsets are deduced therefrom to be applied to respective (T1–T8) so as to focus said acoustic wave impulses onto the gas bubble (5);
in that, during the step (d), instants at which acoustic wave impulses (S2) are emitted by the various impulse firing transducers (T1–T8) are determined so that each wave impulse (2) generated by the impulse firing transducers reaches the gas bubble (5) either during a contraction stage if the wave impulse is compression wave, or during an expansion stage if the wave impulse is an expansion wave;
and
in that, during the step (e), the impulse firing transducers (T1–T8) are caused to generate the acoustic wave impulses at the respective emit instants determined at the step (d), with a second amplitude that is large than the first amplitude.

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