Improving sound diffusion in a reverberation tank using a randomly fluctuating surface

Underwater reverberation environments that satisfy the conditions of uniformity and isotropy of the diffuse field can be used to measure the acoustic characteristics of underwater targets.This study combines two practical indicators—the standard deviation of the absolute sound pressure field(to indicate uniformity)and the analysis of the wavenumber spectrum in the spherical harmonics domain(to indicate isotropy)—for an accurate evaluation of the diffusion of the sound field in a reverberation tank.A method is proposed that can improve the narrow-band diffusion of the sound field by employing a randomly fluctuating surface.An acoustic experiment was performed in a reverberation water tank(1.2 m×1 m×0.8 m),where a randomly fluctuating surface was generated by making waves.The experimental results show that as the wave motion contributes effectively to the random reflection of sound rays in all directions,the uniformity and isotropy are improved significantly when the surface is fluctuating randomly.This work helps to ensure accurate measurements of the characteristics of underwater targets in reverberation tanks.

基于AOTF和LCVR的全偏振反射成像研究

文中提出了一种AOTF与双LCVR相结合的光谱偏振反射成像系统。通过对近景树叶上的病变组织进行单色光成像,获取stokes参量图像,并对图像进行了优化,使得图像细节清晰可见。结果表明,该系统可以对近景物体进行反射光谱偏振成像,为后续进一步研究不同物体表面反射偏振成像提供了可行性.

舌象分析便携式声光高光谱成像技术

本研究提出一种基于窄带声光可调滤波和光纤内窥技术的高光谱成像方法并用于舌象研究。在实验上实时地获得了可见光波段被测舌体的一系列精细图像和光谱信息。研究结果体现了较高的图像分辨率和光谱分辨率。提出的方法能够为舌诊的客观化研究提供有效的光学手段。