In this paper, a surface measurement method based on dual-scan positioning strategy is presented to address the challenges of irregular surface patterns and complex geometries. A confocal sensor with an internal scanning mechanism was used in this study. By synchronizing the local scan, enabled by the internal actuator in the confocal sensor, and the global scans, enabled by external positioners, the developed system was able to perform noncontact line scan and area scan. Thus, this system was able to measure both surface roughness and surface uniformity. Unlike laboratory surface measurement equipment, the proposed system is reconfigurable for in situ measurement and able to scan free-form surfaces with a proper stand-off distance and approaching angle. For long-travel line scan, which is needed for rough surfaces, a surface form tracing algorithm was developed to ensure that the data were always captured within the sensing range of the confocal sensor. It was experimentally verified that in a scanning length of 100 mm, where the surface fluctuation in vertical direction is around 10 mm, the system was able to perform accurate surface measurement. For area scan, XY coordinates provided by the lateral positioning system and the Z coordinate captured by the confocal sensor were plotted into one coordinate system for 3D reconstruction. A coherence scanning interferometer and a confocal microscope were employed as the reference measurement systems to verify the performance of the proposed system in a scanning area of 1 mm by 1 mm. Experimental data showed that the proposed system was able to achieve comparable accuracy with laboratory systems. The measurement deviation was within 0.1 µm. Because line scan mechanisms are widely used in sensor design, the presented work can be generalized to expand the applications of line scan sensors.

A minimized linear ultrasonic motor was proposed, and two flexural bimorph vibrators were utilized to form its stator. The construction of the linear ultrasonic motor and its operation principle was introduced. Two working modes with the same local deformation distribution were chosen on the basis of Finite Element Analysis (FEA). To obtain its optimized structural parameters, sensitivities on frequency difference were calculated, and a way of decreasing the frequency difference of two working modes was introduced. A prototype of the optimized model was made. The modal testing of the stator and its performance evaluation was conducted. The modal testing results were in good agreement with that of the simulation. The maximum speed of the prototype is 245 mm/s, and its maximum thrust is 1.6 N.

In this paper, a novel design of a surface topography measurement system is proposed, to address the challenge of accurate measurement in a relatively large area. This system was able to achieve nanometer-scale accuracy in a measurement range of 100 mm × 100 mm. The high accuracy in a relatively large area was achieved by implementing two concepts: (1) A static coordinate system was configured to minimize the Abbe errors. (2) A differential measurement configuration was developed by setting up a confocal sensor and a film interferometry module to separate the motion error. In order to accommodate the differential measurement probes from both sides of the central stage and ensure the system rigidity with balanced supports, separate linear guides were introduced in this system. Therefore, the motion Degree of Freedom (DoF) was analyzed in order to address the challenge of an over-constrained mechanism due to multiple kinematic pairs. An optimal configuration and a quick assembly process were proposed accordingly. The experimental results presented in this paper showed that the proposed modular measurement system was able to achieve 10 nm accuracy in measuring the surface roughness and 100 nm accuracy in measuring the step height in the range of 100 mm × 100 mm. In summary, the novel concept of this study is the build of a high-accuracy system with conventional mechanical components.

Micro-coordinate metrology is currently limited when the probing system works on the microscale, especially when measuring high aspect ratio microstructures with horizontal internal dimensions below $100~\mu \text{m}$ due to the oversized probe ball tip and short stylus length. The accuracy and reliability of the measurement are also influenced by the surface interface effects. To solve these existing problems, we developed a nano precision probing system with a micro monolithic tungsten ball tip. Initially, the surface interaction effects during the tip-surface approaching tests are investigated. On this basis, the probe was designed to use surface interaction forces as the triggering force. The sensing principle of the optimized optic lever light paths is investigated and analyzed to acquire the isotropic sensitivity. The elastic mechanism with isotropic stiffness suitable for small triggering forces is designed through ANSYS software. The modeling of the probe and the mechanical design as well as the assembly of the micro stylus are reported. Experimental tests demonstrate that the probe can operate in a noncontact mode with 1-nm resolution, and the repeatability is better than 16 nm. The permissible measurement range is $\pm 10~\mu \text{m}$ in the $x$ - and $y$ -axes and $10~\mu \text{m}$ in the $z$ -axis. The comprehensive uncertainty of the probing system is 16 nm. The probe is also verified by measuring a micro hole and a microgroove. The developed probing system is well-suited for high aspect ratio microstructure measurements with horizontal internal dimensions below $100~\mu \text{m}$ .