Abstract:A micro Coordinate Measuring Machine (CMM) with the measurement volume of 50 mmˆ50 mmˆ50 mm and measuring accuracy of about 100 nm (2σ) has been developed. In this new micro CMM, an XYZ stage, which is driven by three piezo-motors in X, Y and Z directions, can achieve the drive resolution of about 1 nm and the stroke of more than 50 mm. In order to reduce the crosstalk among X-, Y-and Z-stages, a special mechanical structure, which is called co-planar stage, is introduced. The movement of the stage in each direction is detected by a laser interferometer. A contact type of probe is adopted for measurement. The center of the probe ball coincides with the intersection point of the measuring axes of the three laser interferometers. Therefore, the metrological system of the CMM obeys the Abbe principle in three directions and is free from Abbe error. The CMM is placed in an anti-vibration and thermostatic chamber for avoiding the influence of vibration and temperature fluctuation. A series of experimental results show that the measurement uncertainty within 40 mm among X, Y and Z directions is about 100 nm (2σ). The flatness of measuring face of the gauge block is also measured and verified the performance of the developed micro CMM.

Articulated Arm Coordinate Measuring Machine (AACMM) is a kind of portable coordinate measuring equipment with a flexible structure, which employs a series of rotating components around generally perpendicular axes. As a portable device, the probe parameters of AACMM will change after probe switching or dismounting and reassembling the same probe during shipping AACMM from one place to another to carry out measurement tasks. As incorrect coordinates will be given without the correct probe parameters, the probe parameters must be re-identified. By analyzing the identifiability of geometrical parameters of kinematical model and presenting the non-redundant-parameter model in this paper, a simple approach for the probe parameters calibration of AACMM is proposed, to improve its portability and ensure the accuracy of AACMM. In addition a very simple accessory was designed to hold the spherical probe as a data capture device. Gauss-Newton method was adopted as an optimization method to figure out the probe parameters. A program was developed to carry out the calibration process. Experimental results prove that the calibration approach proposed in the paper was effective.

Optical beam deflection detection is one of the main techniques used to detect the vibrating amplitude of dynamic mode atomic force microscope cantilevers. Due to the limitations of optical beam deflection detection systems and cantilevers, light leakage of the incident laser beam around the cantilevers can occur. An interference effect between the reflected beam from the cantilever and some scattered light from the specimen surface occurs, and an interference error in the probe tip–specimen approaching curve arises from this effect. In this paper, the interference effect in a dynamic atomic force microscope is analysed and observed in different conditions, and the micro-profile measurement error caused by the optical interference is deduced and calculated mathematically. The influence of the interference effect on a grating pattern measurement is then simulated.

The trend toward miniaturization in manufacturing has led to a requirement for micro/nano measuring techniques capable of measuring tiny features on small components. In this paper we propose and demonstrate a novel scheme for micro/nano displacement measurement based on a double-FBG (fiber Bragg grating) sensing structure, a suspended FBG probe stem and a fiber fused micro-ball tip. Such a scheme has some advantages including robustness, sensitivity, small size with large aspect ratio attainable, simplicity and economy. The preliminary experiments showed that the prototype yielded a measurement resolution of 10 nm and a nonlinear error of 150 nm.

Accuracy Distribution and Determination is one key step in instrument design and it influences manufacturing cost and final accuracy of machine. So, the analysis about instrument accuracy needs to be paid more attention before manufacturing. Flexible CMM has attracted lots of eyes recent years in the world. This paper gives the analysis result of the flexible CMM. At first, a typical flexible CMM is briefly introduced and the system combines 6 angle encoders and 2 measuring arms and one probe. Secondly, the measuring mathematic model is derived and the error of the parameters of the system is analyzed base on the model. Thirdly, the accuracy of the key parameters of the system have been distributed and determined according to the analysis. Finally, the theory has been approved in a practical flexible CMM. So, the theory of accuracy distribution and determination is the basement of design and manufacturing and it plays a great role in the instrument design.