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S. Sadana, S. Yadav, N. Jha, V. Gupta, R. Agarwal, A. Bandyopadhyay and T. Saxena

A Computer Controlled Precision High Pressure Measuring System

A microcontroller (AT89C51) based electronics has been designed and developed for high precision calibrator based on Digiquartz pressure transducer (DQPT) for the measurement of high hydrostatic pressure up to 275 MPa. The input signal from DQPT is converted into a square wave form and multiplied through frequency multiplier circuit over 10 times to input frequency. This input frequency is multiplied by a factor of ten using phased lock loop. Octal buffer is used to store the calculated frequency, which in turn is fed to microcontroller AT89C51 interfaced with a liquid crystal display for the display of frequency as well as corresponding pressure in user friendly units. The electronics developed is interfaced with a computer using RS232 for automatic data acquisition, computation and storage. The data is acquired by programming in Visual Basic 6.0. This system is interfaced with the PC to make it a computer controlled system. The system is capable of measuring the frequency up to 4 MHz with a resolution of 0.01 Hz and the pressure up to 275 MPa with a resolution of 0.001 MPa within measurement uncertainty of 0.025%. The details on the hardware of the pressure measuring system, associated electronics, software and calibration are discussed in this paper.

Open access

P.S. Malviya, N. Yadav and S. Ghosh

Abstract

The present paper is aimed to the exploration of acousto-optic (AO) modulational amplification in ion implanted semiconductors. The AO modulational process has been treated as a four wave parametric mixing process and the effective third-order acousto-optic susceptibility characterizing the instability process has been deduced. By considering that the origin of modulational interaction lies in the third order AO susceptibility arising from the nonlinear induced current density and using the coupled mode theory, an analytical investigation of an intense laser beam in a strain dependent dielectric constant (SDDC) semiconductor crystal is presented. We found a significant change in threshold and gain characteristics with changes in charge imbalance parameter. The presence of colloidal grains (CGs) plays an effective role in changing the threshold intensity and effective gain constant.