High-extinction VIPA-based Brillouin spectroscopy of turbid biological media

TL;DR

This paper introduces a VIPA-based spectrometer with a Fabry-Perot filter enabling high-extinction, background-free Brillouin spectroscopy in turbid biological media, extending the technique's applicability to opaque tissues.

Contribution

The development of a novel spectrometer combining VIPA stages and a Fabry-Perot interferometer for effective Brillouin spectroscopy in turbid media.

Findings

Achieved background-free Brillouin spectra in Intralipid solutions.

Demonstrated Brillouin measurements up to 100 microns deep in chicken muscle tissue.

Enhanced spectral extinction allows application to opaque biological samples.

Abstract

Brillouin microscopy has recently emerged as powerful technique to characterize the mechanical properties of biological tissue, cell and biomaterials. However, the potential of Brillouin microscopy is currently limited to transparent samples, because Brillouin spectrometers do not have sufficient spectral extinction to reject the predominant non-Brillouin scattered light of turbid media. To overcome this issue, we developed a spectrometer composed of a two VIPA stages and a multi-pass Fabry-Perot interferometer. The Fabry-Perot etalon acts as an ultra-narrow band-pass filter for Brillouin light with high spectral extinction and low loss. We report background-free Brillouin spectra from Intralipid solutions and up to 100 microns deep within chicken muscle tissue.