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 divided into four sectors connected to a high voltage generator. The resulting electric field is used to levitate a moving metallic plate which carries the unknown mass. A prototype of the capacitor-based scale has shown an uncertainty of a few tenths of grams in the range of 0 g to 250 g.

Nowadays CENAM is being developing the national standard of density, standard that will offer traceability on density measurements to all our country.

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.

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 simulation results and our method has a possibility to evaluate the depth of the microcrack quantitatively.

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 beamsplitter (PBS) or a rotatable polarizator. The utility of this new concept has been demonstrated by several measurements on a tensile testing machine.