D形分光瞳共焦布里渊光谱探测系统

D-Shaped Divided Aperture Confocal Brillouin Microscopy

共焦布里渊光谱技术因其具有非接触、无损伤、高空间分辨等优点,在生物医学、物理化学以及材料科学中被广泛应用。由于布里渊散射频移较低、强度较弱,在弹性散射光没有被充分抑制的情况下,布里渊散射光容易受到弹性散射光的影响,导致光谱测量结果精度的下降,而且传统共焦布里渊光谱系统仍存在光谱轴向分辨力与层析能力不足等缺点,严重限制了共焦布里渊光谱探测系统在高散射样品以及长工作距离光谱探测领域中的应用。为改善共焦布里渊光谱探测系统的抗弹性散射能力、光谱轴向分辨力以及层析能力,构建了一种D形分光瞳共焦布里渊光谱探测系统。该系统通过侧向照明与侧向收集的方式消除背向散射,降低弹性散射强度,有效抑制弹性散射对布里渊散射的干扰,进而提高共焦布里渊光谱探测系统的抗弹性散射能力。通过D形光瞳对照明点扩散函数与收集点扩散函数进行调制,利用斜入射的方式使照明点扩散函数与收集点扩散函数仅在焦平面上发生重叠,在轴向上实现三维点扩散函数的压缩,有效去除离焦光谱信息对焦面光谱信息的干扰,降低轴向光谱强度响应曲线的半高全宽与全高全宽,进而达到提高共焦布里渊光谱探测系统的光谱轴向分辨力以及层析能力的效果。实验表明:相比于共焦布里渊光谱探测系统,D形分光瞳共焦布里渊光谱探测系统的抗弹性散射能力与层析能力得到大幅提升,通过优化光瞳参数,其光谱轴向分辨力可以提高30%以上,进而可以有效解决多层样品中的光谱串扰问题。D形分光瞳共焦布里渊光谱探测系统作为一种具有高层析能力、抗弹性散射能力强的布里渊光谱探测系统,为布里渊光谱技术在现代前沿基础学科领域中的进一步应用提供了有力保证。

Confocal Brillouin microscopy(CBM)provides a non-contact,non-destructive,and high spatial resolution measurement,which has widely been applied in biomedical detection,physical chemistry,and materials science.The Brillouin scattering frequency is low,and the intensity is weak,so the signals can be easily overlapped or even overwhelmed in the case where the elastically scattered light is not sufficiently suppressed,which significantly limits measure accuracy of the Brillouin spectrum.In addition,the spectral axial resolution and tomography ability of CBM is still insufficient,which limit applications in the fields of high scattering samples and large working distance.In this paper,a D-shaped divided aperture confocal Brillouin microscopy(DDACBM)is proposed to improve the anti-elastic scattering ability,spectral axial resolution,and tomographic capability of CBM.DDACBM eliminates the backscattering light and reduces the crosstalk between the elastic scattering and Brillouin scattering by symmetrical lateral offset illumination and lateral offset detection.Thus the anti-elastic scattering ability of CBM is improved.And the point spread function of the illumination light path and the collection light path is modulated.The illumination light path and the collection light path only overlap on the focal plane by the inclined incident.Therefore,threedimensional point spread function is compressed in the z-axis,and the interference between the defocused plane and the focal plane is effectively removed.The full width at half maximum and a full maximum of the axial spectral intensity response curve reduce,thereby the spectral axial resolution and tomography ability of the CBM are improved.Experiments show that DDACBM improves the anti-elastic scattering ability and tomographic capability of the CBM.And by optimizing the pupil parameter,the spectral axial resolution is improved by more than 30%,which can effectively reduce the spectral crosstalk in multi-layer samples.DDACBM provides a guarantee for further applications of Brillouin spectrum technology in the modern basic research fields.