In view of the fact that the application field of a dual tunneling-unit scanning tunneling microscope (DTU-STM) was strongly limited by sample conductivity, a dual imaging unit atomic force microscope (DIU-AFM) was developed for wide-range nano-metrology. A periodic grating is employed as a reference sample. The DIU-AFM simultaneously scans the grating and a test sample by using one single XY scanner. Their images thus have the same lateral size, and the length of the test sample image can be precisely measured by counting the number of periodic features of the reference grating. We further developed a new method of implementing wide-range nano-metrology. By alternatively moving the XY scanner in the X direction using a step motor, a series of pairs of images are obtained and can be spliced into two wide-range reference and test ones, respectively. Again, the two spliced images are of the same size, and the length of test image can be measured based on the reference grating features. In this way, wide-range metrology with nanometer order accuracy is successfully realized.
In this paper, a new type of AFM scanning in liquid is developed. It circumvents the limitations of scanning electron microscopy by working in-situ, facilitating real-time studies of iron corrosion. We briefly introduce the structure of the AFM probe, liquid cell, scanning and photoelectronic feedback control system for image scanning and processing in liquid. By using the AFM scanning in liquid, a process of metal corrosion in liquid circumstance can be observed and the real-time images of the sample surface were successfully gained. The results indicated that although corrosion generally appears to be a macroscopic phenomenon, it typically begins at the atomic or near atomic level. And the experiments also show that this system could avoid the effect of surface tension and vibration on AFM images and was not restricted by sample's size and weight. It is of high repeatability, reliable stability and ideal contrast for image acquisition, and has a resolution of better than 1nm, covering a scan range from 100 nm x 100 nm to 10 mm x 10 mm.