Papers by Keyword: Photoacoustics

Abstract: Zircaloy-2, an useful nuclear material is studied here by photoacoustics to correlate with the measurements of X-rays. The microstructure variations observed in X-rays could be explained on the basis of thermal diffusivity measured by photoacoustics technique.

Abstract: The nuclear material, Zircaloy-2 is studied here by photoacoustics and the results are correlated with ultrasonic measurements and metallographic microstructures. Precipitation of hard intermetalics and formation of α-martensite, due to thermal aging are also explained through photoacoustic studies.

Abstract: Alloy D9 is a candidate material for core components of fast breeder reactors. This alloy has been 20% cold worked and thermally aged at 1073 K for different time durations and their thermal properties have been studied using photoacoustic (PA) measurements. The results of the PA measurements have been correlated well with the ultrasonic velocity and hardness measurements.

Abstract: New software using VEE Pro was developed to integrate the various components of photoacoustic spectrometer through RS-232 interface and this is the first time such an effort is made not only to integrate but also to automatically acquire the data for depth profile and wave length scanning. The performance and validity was rigorously tested for repeatability and standard error for samples like air, glass and silicon wafer. As an application towards NDE, the thermal parameters obtained from photoacoustics are compared with ultrasonics and discussed.

Abstract: Photoacoustic spectroscopy (PAS), which is widely used in gas sensing applications, is capable of a wide dynamic range, simplicity of use, high selectivity and sensitivity and also possesses novel detection characteristics when the cell are scaled into a micro system design. In a PAS system which is based on the photoacoustic effect, if the parameters of light power, chopper frequency, and absorption coefficient of the target analyte were decided, the level of the acoustic signal is inverse proportional to the radius square of the cell in which the sample is laid. So, miniaturizing the size of the cell can improve the system’s sensitivity. In our experiment, we initially designed a macro photoacoustic non-resonant cell (PNC) using stainless steel. As the macro cell is scaled to a dimension approaching the microelectromechanical systems (MEMS) level, the basic information gained from these initial tests is a special reference to fabricating a MEMS scale device. The non-resonance test conducted at 100 Hz demonstrated large signals (15.89mV) for CO₂ concentrations at 600 ppm and high signal-to-noise (S/N) values (~ 85:1). Then a structure of monolithic MEMS photoacoustic cavity was proposed which incorporate a three-wafer.