Spectral broadening in Brillouin imaging

Abstract

Brillouin microscopy is an emerging imaging modality that provides fundamental information about mechanical properties of media in a non-contact manner. To date, low numerical aperture (NA) optics have been used, due to noticeable angular broadening of the Brillouin spectrum at higher NAs. In this work, we investigate theoretically and experimentally the dependence of spectral broadening effects in Brillouin imaging on system NA, for both 90 degrees and 180 degrees scattering geometries. Lineshape deformations and broadening are found to be minimised in a backscattering geometry, hence paving the way for high resolution in-vivo mechanical imaging. (C) 2013 AIP Publishing LLC

Quantification of plaque stiffness by Brillouin microscopy in experimental thin cap fibroatheroma

“…Electronic supplementary material, figure S1 shows a diagram of the optical system. A backscattering geometry was used to minimize the spectral broadening of the Brillouin peaks owing to the high numerical aperture (NA) lens used [9]. The light of a single longitudinal-mode laser (l ¼ 561 nm) was focused onto the sample by an oil-immersion microscope objective lens (100Â, NA ¼ 1.3).…”

“…The spectrum of light scattered by thermal acoustic waves in the sample is analysed to measure the Brillouin frequency shift, which is related to the elastic modulus (see electronic supplementary material for further details). Brillouin microscopy has been used to measure the frequency shift of the eye lens [6] and cornea [7], including a human lens in vivo [8], and it has been recently shown to be capable of subcellular resolution [9]. Herein, we designed and built a high-resolution confocal Brillouin microscope and used it to measure local frequency shift variations of mouse carotid artery sections containing TCFA.…”

High Speed Sub-GHz Spectrometer for Brillouin Scattering Analysis

“…Due to its low acquisition time and illumination power such a spectrometer can be used for measuring biomedical materials noninvasively, enabling Brillouin spectroscopy to become a useful tool through high resolution in vivo-mechanical imaging 4,6,10,11 . Several groups using this type of spectrometer have demonstrated a variety of applications such as measuring the rheological properties of the eye lens 12 , detecting bacterial meningitis in spinal fluid 13 , and analyzing the corneal elastic modulus 14 .…”

Optimizing signal collection efficiency of the VIPA-based Brillouin spectrometer

“…26 Without an equivalent confocal pinhole (e.g., without an SM¯ber), this broadening e®ect cannot be e±ciently suppressed. 8,27 In the speci¯c measurements shown in Figs. 2(a) and 2(c), the Brillouin line was broadened by 5 pixels (i.e., $400 MHz in Brillouin shift).…”