Two novel micro/nano moire method, SEM scanning moiré and AFM scanning moire techniques are discussed in this paper. The principle and applications of two scanning moire methods are described in detail. The residual deformation in a polysilicon MEMS cantilever structure with a 5000 lines/mm grating after removing the SiO2 sacrificial layer is accurately measured by SEM scanning moire method. While AFM scanning moire method is used to detect thermal deformation of electronic package components, and formation of nano-moire on a freshly cleaved mica crystal. Experimental results demonstrate the feasibility of these two moire methods, and also show they are effective methods to measure the deformation from micron to nano-scales.
A new phase shifting SEM scanning moire method is proposed in this paper. The phase shifting technique is realized in four steps from 0 to 2 π by shifting electron beam in y-axis direction controlled by SEM system. It is successfully applied to measure the virtual strain of a MEMS structure with grating of 5000 lines/mm. The experiments prove the technique can be widely used in meso-deformation measurement, and also show the sensitivity of experiments is highly improved after phase shifting technique. It provides a new way for disposal of fringes patterns in sub-micro moire method.
A new moire interferometer, known as multifunction 3D function interferometry system is developed by authors, which combines the advantages of four-beam moire interferometer with the Twyman/Green interference system. The system can measure in-plane and out-of-plane deformation synchronously with high accuracy and high sensitivity. A compact phase shifter is used to improve the measurement sensitivity. The optical theory, components, key techniques, unique ability, and specifications of the system are described in detail in this paper. Some typical experiments using this system have been done and gained good results.