Simultaneous, multipoint single-shot coherent Rayleigh--Brillouin scattering

A novel, to the best of our knowledge, laser diagnostic technique enabling simultaneous velocity measurements at different spatial locations is presented. Using single-shot coherent Rayleigh-Brillouin scattering (CRBS) and spatially splitting the signal beam, we show that distinct regions within the probe volume can be measured independently and simultaneously, thus enabling localized flow diagnostics at the micrometer scale. To demonstrate the new technique, measurements are performed in the flow of an under-expanded jet featuring sharp radial velocity gradients and microscale flow structures, which are probed through the spectroscopic signatures in two different signal beams. Velocity component extracted from the acquired spectra reveals flow-dependent signatures. The method presented here is inherently scalable through optical design modifications, offering a powerful, flexible diagnostic tool for detailed thermodynamic characterization of neutral gas and plasma flows in complex environments.