New optically powered pressure sensor with optical fiber link

Abstract

An optically powered sensor for measuring pressure which linked by optical fiber is developed in a new scheme. Its pulse position modulation (PPM) optical signal and optical supply power for electronics in probe are transmitted to and fro via a single optical fiber. The optical power is carried by a laser diode (LD) source with 1300 nm wavelength and the sensing data are carried by LED 850 nm source. The remote probe uses all CMOS chips and particular modulations (PPM and PWM). Its electrical consumption including signal manipulation and LED driven current from optical conversion is less than 100 (mu) W. The laser diode supplies 5 mW of optical power into the fiber. An advanced photodetector converts sufficiently the section of this power into electrical power to drive the whole probe operation. The optically powered distance gets up to 500 m. The novel sensor combines advanced optical fiber and electronics technology into a system. It continuously measures pressure in real time. Because of using the principle of ratio measurement between mesurand and reference signals, as well as light feedback for light source stability, the system is available with high reliability, outstanding accuracy, and repeatability.