This paper deals with two scales that are conceived to operate inside a freeze-dryer, where the environmental conditions (temperature down to -80 ºC and pressure down to 0.5 Pa) prevent traditional mass transducers to be employed. One scale is based on a parallel-electrode capacitor, whose capacity depends on the position of a moving electrode that, in turn, depends on the unknown mass. The capacity change is converted into a frequency change by means of an oscillator circuit. The second scale, which is still under development, is based on electrostatic levitation. A fixed metallic plate is...
Misalignment during the mounting of torque transducers in calibration devices can cause parasitic bending inside the transducers. Flexible couplings allow the contribution of misalignment to the measurement uncertainty to be reduced to a negligible amount.
deadweight machines have followed an evolution from the traditional fixed-sequence machine to modern automatic machines that with a small number of masses can generate a large number of load increments. The new machine made by T.M.T. is based on the substitution principle, but every group of masses has a specific actuator, allowing independent substitution. The change of force from one step to the subsequent step follows closely a given time function without overloading due to dynamic effects. The mass management system does not need, therefore, to maintain the force constant using the...
Recent important progress in Dual frequency He-Ne lasers is reported, including two methods and experimental results to avoid mode competition and generate the frequency difference covering of 1~40 MHz, and the principle and the experiments of making a birefringence dual frequency laser itself be a displacement sensor with l/8 resolution, 8mm measurement range, and the function of selfcalibration.
We have continued research on 3D shapes measurement system using spatial modulator. The advantages of this system are non-contact, non-invasive, and short time measurement. We proposed a method using differentiation to expand the measurable area and improve the accuracy of measurement. Additionally, We proposed to eliminate the influence of marking on target object surface. It was a very practical and effective method.
This paper describes the characteristics of the laser backscattering pattern of the microcrack on the ultra-fine finished surface of brittle material. The relation between the periodic backscattering pattern and the depth of the microcrack is made clear by employing the Boundary Element Method (BEM) simulations of electromagnetic wave scattering. The backscattering patterns are measured for the indentation microcracks with the depth of less than a hundred micrometer on the smooth glass surface. Experimental results show that the measured laser backscattering patterns agree with the...
A new optical measurement method for detecting the semiconductor pattern defects, which does not depend on the physical limit of optical image formation, is presented. The experimental system consists of the Fourier transform optical system using of a high-power objective. In order to verify the feasibility of application of our proposed method to next-generation patterned wafer inspection technique, several primary experiments were carried out. It is shown that the proposed method is effective for detecting the small particle contaminants on the semiconductor circuits.
Shearography is a full field interferometric technique for the measurement of small deformation gradients. The main applications are non-destructive testing in material inspection and quality control. This contribution intends to present a new image shearing speckle pattern interferometer set-up for simultaneous measurement of two independent deformation gradients equivalent to two shear directions. Herein, we use the polarization effect to separate the two directions. The selection of the polarized images, which correspond to the shear direction, has been performed either by a polarization...
Developments in electronic dosemeters have been made recently for photons and neutrons using pin-diode. In this paper the response of the sensor is modeled by applying appropriate simulation codes for the pulse height distribution (energy response) for photon irradiations. Good agreement between experimental data and model calculations for narrow spectra x-ray and standard radionuclides was found. The important interaction regimes are interpreted correctly.