Fig. 1. The effect of waist radius and cylindrical lens focal lengths on dispersion rate. (a) VIPA output spectra at W=3 mm, 6 mm, and 9 mm, respectively; (b) the intensity difference at different waist radii; (c) the intensity difference at different focal lengths of cylindrical lens

Fig. 2. The effect of F on dispersion rate. (a) Envelop of VIPA output spectra at F=1000 mm, 500 mm, and 250 mm, respectively; (b) VIPA output spectra at F=1000 mm, 500 mm, and 250 mm, respectively; (c) the position of the highest order of VIPA output spectra varing with F; (d) the dispersion rate and the intensity difference between the highest order and the next order of VIPA output spectra varing with F

Fig. 3. The effect of VIPA tilting angle on dispersion rate. (a) The position of the P₁ order of VIPA output spectra varing with θt; (b) the dispersion rate and the intensity of the P₁ order of VIPA output spectra varing with θt

Fig. 4. The effect of camera pixel on dispersion rate. (a) Distribution of output optical when camera pixel is 1024×1024; (b) change of dispersion rate versus camera pixel value; (c) the one-dimensional spectra distribution curve at the red line position in Fig. 4(a) when camera pixel is 1024×1024 and 6000×6000, respectively

Fig. 5. The effect of waist radius, cylindrical lens focal lengths, focal lengths of spherical lens, and VIPA tilting angle on intensity difference and the dispersion rate. (a) The intensity difference between P₂ and P₁ at different waist radii and cylindrical lens focal length; (b) the intensity difference between P₂ and P₃ at different waist radii and cylindrical lens focal length; (c) the intensity difference between P₂ and P₁ at different focal lengths of spherical lens and VIPA tilting angle; (d) the intensity difference between P₃ and P₂ at different focal lengths of spherical lens and VIPA tilting angle; (e) the dispersion rate between P₂ and P₁ at different focal lengths of spherical lens and VIPA tilting angle; (f) the dispersion rate between P₃ and P₂ at different focal lengths of spherical lens and VIPA tilting angle

Fig. 6. Brillouin detection system experimental device

Fig. 7. Brillouin spectra of water and olive oil. (a)(b) Brillouin signals of water and oil when FSR of VIPA is 30 GHz, respectively; (c) Brillouin signals of water when FSR of VIPA is 20 GHz; (d) Brillouin signals of water when FSR of VIPA is 20 GHz

Fig. 8. Comparison of EMCCD and CMOS system parameters. (a) Extinction ratio; (b) dispersion rate, spectra resolution, measuring accuracy of Stokes, and contrast

Fig. 9. Measurements of Brillouin frequency shift of cornea and lens in an ex-vivo porcine eye. (a) Image based on measured frequency shifts at the center of cornea; (b) image based on measured frequency shifts of lens in red box region of Fig.9 (a) at a depth of 4 mm from the corneal surface

Table 1. Initial parameter settings for simulation of a single-stage VIPA spectrometer

Table 2. Parameters setting of the single-stage VIPA spectrometer