Sensor-less adaptive optics for Brillouin micro-spectroscopy

Abstract: Brillouin spectroscopy is a powerful optical technique for viscoelastic characterization of samples without contact. However, like all optical systems, Brillouin spectroscopy performances are degraded by optical aberrations, and have therefore been limited to homogenous transparent samples. To correct for aberrations, adaptive optics (AO) methods have been previously integrated into a variety of optical modalities ranging from ground-based telescopes to super-resolution microscopes. In this work, we developed an adaptive optics configuration designed for Brillouin scattering spectral analysis. Our configuration doesn't require direct wave-front sensing and the injection of a 'guide-star'; hence, it can be implemented without the need for sample pre-treatment. We used our AO-Brillouin spectrometer in aberrated phantoms and biological samples; consistent with previous AO systems, we demonstrate effective correction of optical aberrations yielding 2.5-fold enhancement in Brillouin signal strength and 1.4-fold improvement in axial resolution.