Grueneisen relaxation photoacoustic microscopy

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Article number174301
Journal / PublicationPhysical Review Letters
Volume113
Issue number17
Online published20 Oct 2014
Publication statusPublished - 24 Oct 2014
Externally publishedYes

Abstract

The temperature-dependent property of the Grueneisen parameter has been employed in photoacoustic imaging mainly to measure tissue temperature. Here we explore this property using a different approach and develop Grueneisen relaxation photoacoustic microscopy (GR-PAM), a technique that images nonradiative absorption with confocal optical resolution. GR-PAM sequentially delivers two identical laser pulses with a microsecond-scale time delay. The first laser pulse generates a photoacoustic signal and thermally tags the in-focus absorbers. When the second laser pulse excites the tagged absorbers within the thermal relaxation time, a photoacoustic signal stronger than the first one is produced, owing to the temperature dependence of the Grueneisen parameter. GR-PAM detects the amplitude difference between the two colocated photoacoustic signals, confocally imaging the nonradiative absorption. We greatly improved axial resolution from 45μm to 2.3μm and, at the same time, slightly improved lateral resolution from 0.63μm to 0.41μm. In addition, the optical sectioning capability facilitates the measurement of the absolute absorption coefficient without fluence calibration.

Citation Format(s)

Grueneisen relaxation photoacoustic microscopy. / Wang, Lidai; Zhang, Chi; Wang, Lihong V.
In: Physical Review Letters, Vol. 113, No. 17, 174301, 24.10.2014.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review