As an important measuring technique, white light scanning interferometry can realize non-contact, fast and high accurate measurement. However, when measuring the large step structure, the white light scanning interferometry has the problems of long time consumption and low signal utilization. In this paper, a kind of adaptive scanning technique is proposed to measure the large step structure to improve its efficiency. This technique can be realized in two ways-the pre-configuration mode and the auto-focusing mode. During the scanning process, the image collection is limited within the coherence area, and in other positions, the motion is speeded up. The adaptive scanning is driven by the nano-measuring machine (NMM) which reaches nanometer accuracy and is controlled by the measurement software. The testing result of 100μm step height shows that the adaptive scanning can improve the measuring efficiency dramatically compared with conventional fixed-step scanning and it keeps the same high accuracy.
Microscopic interferometry can be applied in the step height evaluation with sub-nanometer vertical resolution. This
paper describes the effect of outside vibration on the evaluation process through many experiments. A micro actuator
with high accuracy is used as the simulation of outside vibration. Experiments are done on the system with different
vibration amplitudes, vibration frequencies and phase extracting algorithms. The experimental results show that different
phase extracting algorithms have different responses to the outside vibration; low frequency has a strong effect on the
measurement values when the vibration amplitude is below a threshold value; however, the effect on the step height
evaluation is small by averaging many profiles.
This paper introduces a precise way of using linear structured light sensor and CCD camera to measure the workpieces'
shoulder characteristic size. The high precision measuring system and the core algorithms are mentioned in the paper to
test the deformation of the light plane when the light meets the workpieces' shoulder surfaces. The measuring principle
and the set-up of the system are described in detail. The core sub-pixel algorithms are proposed to locate the deformation
of the structured light in order to improve the final precision. The experiments demonstrate the high repeatability and
accuracy of the system. The experiments of accuracy estimation show the measuring precision could reach 0.05 mm.