Axial imaging property of confocal brillouin microscopy

Confocal Brillouin microscopy device is set up, and Brillouin scattering light of sample is excited using a single-mode laser of 532 nm wavelength. The amplification factor is 100× and the numerical aperture is 0.8. A tandem scanning multi-channel Fabry-Perot (F-P) interferometer is used to collect Brillouin light. In the experiment, the confocal light intensity response curve is measured and the Brillouin spectra of SiO₂ glass, silicon rubber, and polymethyl methacrylate (PMMA) are obtained. Using a novel photon number component factor data process method, the axial imaging resolution is simulated and analyzed. The axial imaging properties of frequency shift, axial acoustic velocity and longitudinal elastic moduli of multi-layer sample of SiO₂ glass-silicon rubber-PMMA are also presented. Error analysis of these three parameters of axial imaging property curve by this method is made as well. The simulation results show that the axial imaging resolution can be improved to about 2 μm with this novel photon number component factor data process method. When the signal-to-noise ratio is greater than 1.46 dB, the accurate Brillouin frequency shift, axial acoustic velocity and longitudinal elastic moduli can be obtained by error relation curves.