Coaxial line scanning Brillouin microscopy with a two-stage parallel VIPA spectrometer for tissue biomechanics

Confocal Brillouin microscopy (CBM) offers high-resolution mechanical imaging but suffers from slow imaging speed due to low scattering efficiency. Line-scanning Brillouin microscopy (LSBM) improves speed by 50–100 times but has limited laser extinction because of the single-stage VIPA spectrometer design. Here, we developed a coaxial LSBM (cLSBM) with a two-stage parallel VIPAs spectrometer, enhancing laser suppression by 23 dB over the single VIPA design. This enables effective line-scanning Brillouin imaging at wavelengths lacking suitable gas chambers. Notably, when combined with a gas chamber, the system achieves over 89 dB laser suppression, allowing direct mechanical mapping of highly scattering biological tissues.