热光非定域螺旋相衬成像(特邀)

Non-local spiral phase contrast imaging with thermal light(Invited)

边缘增强作为一种图像处理技术,对于研究物体边界信息有着重要的应用。根据热光鬼成像的关联机制,将鬼成像与螺旋相衬成像技术相结合,把相位物体与涡旋滤光器非定域地放在热光鬼成像系统的探测光路和参考光路中,建立了相位物体边缘增强识别系统。实验结果表明,采用具有分数阶轨道角动量拓扑荷的涡旋滤波器可以实现轨道角动量值在0~1范围内的相位物体的边缘渐变性增强效果。随着轨道角动量拓扑荷数的增加,相位物体的边缘增强效果会越明显。非定域螺旋相衬成像相较于传统的螺旋相衬成像方案,突破了被测物体和涡旋滤波器在同一光路,并且滤波器必须放置在频谱面的空间局域性限制,解除了对主动照明光源相干性的要求,增强了涡旋滤波相衬成像系统的泛化能力。

As an image processing technology, edge enhancement has important applications for studying the boundary information of objects. According to the correlation theory of thermal light ghost imaging, a phase object edge enhancement recognition system was established by combining the ghost imaging with the spiral phase contrast imaging technology. The phase object and the vortex filter were placed in the signal and idle optical path of the ghost imaging system non-locally. The results prove that by using the vortex filter with the fractional orbital angular momentum(OAM) from 0 to 1, the gradual edge enhancement of the phase object can be realized. The higher the OAM topological charge, the more obvious edge enhancement effect will be.Compared with the traditional spiral phase contrast imaging scheme, the limitation of the filter in the spatial frequency spectrum in the spectral plane is broken by the non-local spiral phase contrast imaging scheme. In addition, the coherence requirement of the active illumination light source is released, and the generalization ability of the spiral phase contrast imaging system is enhanced.