Key Engineering Materials Vols. 381-382

Abstract: This paper presents a method to measure the deformation of large deployable mesh microwave antenna by using the photogrammetric technology. Because the mesh reflector surface is controlled by 79 nodes, measuring 3D coordinates of these nodes accurately is the key to test the deformation of antenna. The technique of camera calibration, the matching method of the image points, and the solution of measuring 3D points are introduced in this paper. The experimental data is also provided. This paper proposes a method to calculate the spatial coordinates of microwave antenna nodes by using the bundle adjustment with distance constraints. This method is capable of correcting the influences of the lens distortion and improving system measurement accuracy. In reference to the fact that the surface of this antenna is controlled by 79 nodes, and the design parameter of these nodes is already known, a method based on digital surface model constrain is used to solve the image points matching problem. This method efficiently simplifies the computation procedure and shortens the measurement time.

Abstract: The inflatable space antenna is gradually used in various spacecrafts because it is portable and foldaway. It is usually made of thin-film materials and has a flexible surface, so that measuring force is not tolerable in measurement process. Close-range photogrammetry is considered as an optimal solution because of its advantages of non-contact operation and fast data acquisition. To improve measuring precision, a method combining bundle adjustment algorithm and the distance constraint is presented in the paper. Two experiments under different conditions are accomplished and experiment results are compared. One experiment is completed with the distance constraint and another without. The experiment results are compared by two parameters: tightness and residuals. The measured object is an inflatable antenna with a 3.5-m diameter.

Abstract: This paper describes a method to characterizing the digital camera. The nonlinear relationship between the RGB signals generated by a digital camera and original image CIEXYZ values was obtained using the polynomial regression procedures. The reasonable structures of the polynomial were found for two digital cameras. The better number of polynomial terms was 19, yielding a modeling accuracy typically averaging 2.1~2.2 E ∆ units and maximally 9.5~10.9 E ∆ units. The experiments results showed that the polynomial regression could be used to characterize commonly digital camera.

Abstract: This paper presents an autofocusing system for an optical microscope (OM) based on a low-cost, highly-sensitive laser focusing probe integrated with a precision stepper positioning stage. During the OM measurement procedure, the laser focusing probe detects variations in the distance between the glass substrate containing the specimen of interest and the OM objective lens and generates a driving signal to adjust the position of the OM via the precision positioning stage such that a precisely-focused image is obtained. The experimental results show that the integrated laser focusing probe and positioning stage complete the autofocusing process within 0.5 seconds.

Abstract: Grind gauge is a measuring tool for size of grains or particles included in paint or ink. Its geometrical specifications and operational procedure are regulated to some extent and partly standardized in both ISO and JIS. However, only skilled technician can manage to handle it properly and to obtain correct measurement results. The objective of this study is to develop an automatic inspection system for the grain or particle size by use of artificial lighting and CCD camera with image processing techniques. A telecentric lens system was constructed and high resolution CCD camera was attached to it. Advantages of coaxial illumination and oblique illumination methods were revealed and their applicability was examined respectively. The optical configuration to cover the scale and the whole groove width of grind gauge was devised so that the captured image data could contain both grain/particle distribution and height location. A proper software program followed by image processing algorithm was established to reveal particle mark and liner mark.

Abstract: In this paper, we proposed a method to attain a high sensitivity of weak optical signal detection by using the multi-wavelength modulation principle. In this method, the optical phase carrying the measurand is obtained by averaging the phases obtained in various orders of heterodyne harmonics. The employment of higher heterodyne harmonics reduces the drift effect in optical detection. The proposed method is demonstrated on the nano-scale displacement measurement by using a single channel fiber interferometer. In the experiment, the displacement is simulated by moving a mirror with a piezoelectric tube. The results show that more repeatable measurements with a resolution of 35nm can be obtained by using the proposed method.

Abstract: This paper proposes an improved active homodyne detection technique to compensate for the drift in homodyne measurement. The technique is implemented on a fiber based Michelson interferometer where a computer controller is designed to drive a piezoelectric cylinder attached to one arm of the interferometer. It is shown that the proposed technique can efficiently stabilize the interferometric output.

Abstract: This paper presents a new set of estimation formulae for non-contact 2D displacement measurement by using the principle of triangulation and the position sensitive detector (PSD) as a 2-D range sensor. It has been shown in theory that the new set of formulae outperforms the conventional formulae by providing much more accurate estimate of the 2D displacement. The theoretical analysis has been verified by simulation studies.

Abstract: The shear force detection by using a tuning fork plays a key role in the implement all kinds of scanning probe microscopes. This paper presents primary results of modeling dynamics of a tuning fork. The obtained model considers not only the piezoelectric properties and mechanical properties of the tuning fork, but also the electric-mechanical coupling between the two prongs of the tuning fork. It has been shown by theoretical studies and experiment results that the theoretical model can fit the amplitude and phase responses of a tuning fork.

Abstract: Nitric oxide (NO) produced in the endothelial cells and other tissues has been known to play a range of physiological roles including vasodilation. Thus, direct in vivo measurement of NO is of great importance for clarification of physiological roles of NO and development of therapeutics using NO. It has long been assumed that NO is readily oxidized in blood and cannot be detected; however, some recent reports demonstrated much longer half-life of NO in the blood stream in vivo. Recently, we reported the basic performance of an NO sensor which is applicable to in vivo measurement. This sensor can detect NO in the blood stream in an anesthetized rat and some biological samples including a dialysis solution. In these studies we found that NO itself showed dynamic changes different from these of oxidative products of NO (nitrite and nitrate) that are conventionally used as indices of NO level. We have also developed a catheter-type NO sensor and demonstrated validity of the sensor for in vivo measurement of NO in the aorta and coronary sinus of anesthetized dogs and rabbits. Both endothelium-dependent and -independent NO productions could be detected. In conclusion, the NO sensor and the catheter-type NO sensor are applicable to direct measurement of NO in biological samples even in vivo and will contribute to clarification of physiological roles of NO.