Low pressure sensor using semiconductor laser

The aim of the present research is to design and study the performance of an optical system for the purpose of measuring the pressure, using semiconductor laser.<br /> A Commercial laser diode of 650 nm Wavelength and 3 mW power is used to measure a low pressure inside a chamber, which is designed for this purpose.<br /> The most important parameter including Threshold current, Energy gap Quantum efficiency,....etc under different values of pressure (1000 mbar-25 mbar) and at room temperature were taken into consideration.<br /> The results show that the laser diode gives a good response to the variation of the pressure inside the chamber, especially, when the laser was operating at pulsed mode.<br /> The main conclusion arrived at, indicates that the laser diode can be used as a sensing unit for low pressure, meanwhile when the pressure decreases; the out put power of the laser diode is increased within 0.091 u-W/mbar.