Laser interferometry is a typical representative of the highest level in the field of geometric metrology, and its accuracy can reach sub-nanometer while taking the light wavelength as a measuring scale. In this paper, we present a precisely controlled transmission structure to realize the conversion between angular and linear displacement, therefore the angular displacement can be obtained based on the high-precision linear displacement measured by the laser interferometric system. By comparing the measured angular values with the reference values, the maximum error of angular displacement measurement in this system is ± 5 arcsec, which is from the calibration certification of the National Institute of Metrology. The reference values are obtained by measuring the angular polygon with a photoelectric autocollimator, and an angular displacement measurement error of ±1 arcsec is achieved based on laser interferometric system in this paper after correcting with a series of conversion coefficients between linear and angular displacement.
Scanning electron microscope (SEM) with feature analysis software has been used for micro-scale surface measurement tasks for many years because of the benefits of fast massive acquisition of nano-scale features, non-contact operation, and automatic data processing. Full information of surface usually needs to obtain in some inspection fields, such as vertical engine part monitoring, cleanliness analysis, melted bead and so on. According to the specific measured feature, the depth mode, resolution mode, and analysis mode of SEM should be firstly determined before use. Therefore, it is important to give user an easy operation mode to get deeper understanding on geometric features, thus offering a significantly enhanced user experience and higher measurement accuracy. Several common aspects of operated behavior should be tested that can cause them to yield larger measurement errors. In this paper, the experimental tests of full information acquisition of multi-scale pitches and step heights samples were respectively performed on a commercial SEM. The influence of the depth mode, resolution mode, and analysis mode of SEM were also discussed on edge features. Experimental results show that our works will be helpful of others who perform similar measurements.
Scanning electron microscope have been widely studied in academia and applied in engine wear monitoring, geology, air cleanliness and pollution, because of the benefits of fast massive acquisition of nano-scale features, non-contact operation, and automatic data processing. It is important to have an automated analysis ability to get a deeper understanding on geometric features of multi-regulars shape of different particles, thus offering a significantly enhanced user experience and higher measurement accuracy. Hence, it should be carried out geometric measurement error tests before using. In this paper, several different shapes of particle were introduced to test geometric measurement error on a commercial SEM with specific particle analysis software. Several experimental cases have been designed by considered of practical application and user habits. Specially, the distinguish accuracy rate of a single threshold and multiple threshold were respectively tested by different types of particles. On the other hand, the ability of automatically classification schemes using the chemical and morphological information was taken in account too. Our scope was indeed narrow, but intentionally so. Finally, we found that these work may be of use to others who perform similar
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