基于双频光栅的微分干涉相衬方法

摘要

针对传统微分干涉相衬技术对双折射性物体成像会有伪像的问题,用双频闪耀光栅取代传统微分干涉相衬的分光元件诺曼斯基棱镜,设计了一种微分干涉相衬方法.对双频闪耀光栅设计,模拟入射平面波通过它之后的光强分布,结果表明它能产生两束剪切角很小的光.用双频光栅微分干涉相衬方法对纯相位样品模拟成像,仿真结果和物体的相位轮廓一致.分析了微分干涉相衬中的相移量和剪切量对成像对比度的影响,加入相移量会明显提高成像图像的对比度,而剪切量越小图像对比度越高.%A new Differential Interference Contrast (DIC) method is proposed based on the DIC theory by replacing the two Nomarski prisms of conventional DIC with bi-frequency blazed gratings, which overcomes the drawbacks of artifacts in the conventional DIC technology. The Bi-frequency blazed gating has been designed, and intensity distributions of plane wave through the grating also have been numerically simulated. The pure phase object and its image are simulated by utilizing grating DIC, and the image agrees with the phase profiles of object very well. Analysis of the influence of shear and bias on the contrast of image demonstrates that image contrast is obviously enhanced when a bias retardation is introduced, and the smaller shear, the higher contrast.