VIPA based high-contrast high-efficiency two-stage Brillouin imaging spectrometer using a single diffraction mask

Abstract

Brillouin spectroscopy is a non-invasive method technique for visualizing the mechanical properties of biological samples with sub-micrometer resolution. However, to obtain 2D or even 3D maps, a high-contrast spectrometer is required to effectively reject spurious signals and isolate the signal of interest. In this work, we present an optimized two-stage virtually imaged phased array-based Brillouin spectrometer capable of achieving a contrast of at least 80 dB thanks to a new single diffraction mask, and thus with an unprecedentedly high overall transmission. Numerical simulations of the electric field propagation through the spectrometer and dedicated experiments validate the increase in contrast. We have used the newly developed Brillouin spectrometer coupled to a confocal microscope to obtain 1 h high-resolution 2D images of about 104 spectra of transparent dental pulp stem cells near a MgF2 interface as well as of the much less transparent porcine dentin material, demonstrating its overall stability and reliability.