A new surface metrology instrument, the ‘Swinging Part Profilometer’ (SPP), has been developed for in-situ measurement of optics undergoing robot-processing in the ground (non-specular) state. In this paper, we present the hardware-design of the SPP, together with software for hardware-control, data-acquisition and surface-reconstruction. First results on a sample part are presented, compared with interferometric metrology, and error-contributions considered. Notably, during each individual scan of a measurement-cycle, the probe remains fixed. This lends itself to automated probe-deployment by the same robot as performs surface-processing, as probe stability is required on only the time-scale for a single scan.
The swing arm profilometer realizes the measurement of the different surface shape by adjusting the axis of the arm bearing and the axis of the workpiece bearing for different spatial positional relationships,so the high precision positional relationship between the axis of the arm bearing and the axis of the workpiece bearing is the premise to obtain accurate result. This paper presents a way using four-based laser trackers to calibrate the axes of the swing arm profilometer,that satisfies the requirement of the high precision and the dynamic calibration. The four-based laser trackers system only uses the precise distances to obtain the coordinates of points. The coordinates of points in the rotate arc of the axes can fit the axes,and the relationship between the axes can be know. The study of the self-calibration of the four-based laser trackers, the arrangement of four-based laser trackers, the design of the calibration method and the processing of measurement data are included in this paper. Finally, the study is validated by the preliminary experiment.
Laser tracker as a three-dimensional measuring instrument for large dimensions is widely used in the industrial measuring system, which is famous for its high precision, high efficiency, in site measurement and easy to be moved or installed, etc. In order to measure the large annular planes, especially non-continuous planes, a method with laser tracker on the basis of station-moving measurement is proposed. In this paper, the working principle of laser tracker system is described firstly, then the principle of the station-moving measurement is analyzed, finally according to the station-moving measurement principle experiment of the flatness measurement of a Φ5000mm round table is carried out, the result is compared with bridge-level, and feasibility of measuring flatness of large precision parts is validated by experiments and analysis results.
When the swing arm profilometer(SAP) measuring the mirror, the effective arm length of SAP which haves an obvious influence on the measurement results of the mirror surface shape needs to be measured accurately. It requires the measurement uncertainty of the effective arm length to reach 10μm in order to meet the measurement requirements, in this paper, we present a kind of technology based on laser tracker to measure the effective arm length of SAP. When the swing arm rotates around the shaft axis of swing arm rotary stage, the probe and two laser tracker balls form three sections of circular arc around the shaft axis of swing arm rotary stage in space. Laser tracker tracks and measures the circular arcs of two laser tracker balls, the center coordinates of the circular plane of circular arc can be calculated by data processing. The linear equation that passes through the two center coordinates is the equation of the shaft axis of rotary stage, the vertical distance from the probe to the shaft axis of rotary stage which can be calculated refer to the equation from the point to the line is the effective arm length. After Matlab simulation, this measurement method can meet the measurement accuracy.
To measure the flatness of the large annular planes, a method with laser tracker on the basis of multi-station and time-sharing measurement principle is proposed in this paper. The laser tracker is used to measure the flatness of large annular planes at different base stations. Based on the redundancy principle, the space coordinates of each measuring point can be determined by large amount of measured data. In the paper, the results of computer simulation for the principle are obtained with several iterative nonlinear algorithms, and it is shown that the method is feasible.
In order to evaluate the task specific measurement uncertainty of laser tracker, based on the analysis of the uncertainties
of the laser tracker system(LTS) ,the Monte-Carlo(MC) method is proposed and applied, and it's principle and steps are
described. We have measured the flatness of the marble table with a laser tracker and a CMM, and compared with the
MC uncertainty simulation. The results of the MC method and laser tracker measurements are in well agreement with
each other, so we conclude that the MC methods could be used in the evaluation of the task-specific measurement
uncertainty of laser tracker.
KEYWORDS: 3D modeling, 3D metrology, Reverse modeling, Bone, Visual process modeling, Data modeling, 3D scanning, Clouds, Mathematical modeling, Structured light
Osteometry is fundamental to study the human skeleton. It has been widely used in palaeoanthropology, bionics, and
criminal investigation for more than 200 years. The traditional osteometry is a simple 1-dimensional measurement that
can only get 1D size of the bones in manual step-by-step way, even though there are more than 400 parameters to be
measured. For today's research and application it is significant and necessary to develop an advanced 3-dimensional
osteometry technique. In this paper a new 3D osteometry is presented, which focuses on measurement of the femur, the
largest tubular bone in human body. 3D measurement based on the structured light scanning is developed to create fast
and precise measurement of the entire body of the femur. The cloud data and geometry model of the sample femur is
established in mathematic, accurate and fast way. More than 30 parameters are measured and compared with each other.
The experiment shows that the proposed method can meet traditional osteometry and obtain all 1D geometric parameters
of the bone at the same time by the mathematics model, such as trochanter-lateral condyle length, superior breadth of
shaft, and collo-diaphyseal angle, etc. In the best way, many important geometric parameters that are very difficult to
measure by existing osteometry, such as volume, surface area, and curvature of the bone, can be obtained very easily.
The overall measuring error is less than 0.1mm.
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