Optical weight measurement system using FBG based D-IM edge filter detection.

• Direct intensity modulation based edge filter detection technique is proposed. • The proposed technique increases system performance of weight measurement system. • It increases the sensitivity and resolution of the system up to two times. • The proposed technique can be integrated with any EFD interrogation system. Fiber Bragg Gratings (FBGs) are extensively used as strain and temperature sensors in various industrial applications. The key task for FBG based sensing system is to convert the optical sensing data into user friendly information that can be interpreted with ease. Edge filter detection (EFD) interrogation technique is commonly used to convert wavelength encoded sensing data into optical power variation. This technique is simple and cost effective as compared to other interrogation technique. While using FBG as both edge filter and sensing element the sensitivity of the system depends upon the slope of its reflection or transmission spectrum. Therefore, there is always a tradeoff between sensitivity and measurement range in this interrogation technique. Direct Intensity Modulation (D-IM) based EFD is proposed in this manuscript, where a tunable laser source is modulated using different message signals and is tuned in the linear region of FBG transmission spectrum. This technique observes the change in amplitude of message signal at the photodetector output due to shift in Bragg wavelength. Later the proposed technique is utilized in optical load cell based weight measurement system to observe the system performance. Maximum sensitivity of 196.7 mV/kg and SNR of 63 dB is obtained by using the proposed technique. Decrease in percent error with enhancement in system resolution is observed, as compared to previously reported conventional EFD technique based optical weight measurement. The proposed technique has shown significant improvement in system performance with nominal increase in system complexity that makes this technique more effective for industrial applications. [ABSTRACT FROM AUTHOR]