一维亚波长周期结构物成像的光子学研究

当用波长为λ的单色平行光垂直照射到光栅常数d<λ的亚波长周期结构衍射物时,会产生隐失波。由于快速衰减,这种亚波长周期物是不能成像的。但是,通过对亚波长周期结构物进行适当的编码后可得到均匀波,使这种携带了隐失波信息的均匀波通过经特别设计的光学系统并被放大到CCD所能识别的像素大小后,再进行必要的解码以滤掉编码波,即可得到原亚波长周期结构衍射物的像,最终达到超分辨的目的。基于这种新颖的成像技术,用常规仪器就实现了对亚波长周期结构物的成像。在运用光子学方法对实验和成像过程进行较为详尽的理论分析的同时,对编码器、解码器的位置以及它们相对物光栅的取向给出了设计性研究,对滤波器的选择给予了必要的说明。实验结果验证了该设计理论的正确性。

Photonic Study on Imaging of One-Dimensional Periodic Object with Subwavelength Structure

When a periodic object with subwavelength structure is illuminated by normal incident monochromatic parallel light,evanescent waves occurs.For the quick attenuation of the evanescent wave,the object with subwavelength structure cannot be imaged properly by ordinary method.However,one-dimensional periodic object with subwavelength structure can be encoded by a grating so that homogeneous waves can be obtained.Passing through the optical system designed specially,the well-distributed waves with evanescent waves information is enlarged so that it can be recognised by CCD camera.After that, the homogeneous waves with evanescent waves information is decoded by a decoding grating,the information of the encoding grating is filtered,and the image of the object with subwavelength structure reappears in the image plane.The imaging technique based on the conventional optical setup is novel for superresolution image of object with subwavelength structure can be obtained.Theoretical analysis of the imaging process and experiment is given well by photonic method.It is designed that where the encoding and decoding gratings are placed,so does how to choose the tilt angles between the two gratings and the object.The low-pass filters used in the novel technique are also discussed.The results of experiments demonstrate that the theory is valid.