System for Condition Based Maintenance

Veraphotonics has developed a multi-function optical sensor product for real-time and continuous crack detection and load monitoring of aircrafts, ships or other critical structures. Using advanced optical frequency demodulation and Field-Programmable Gate Array (FPGA) -based techniques, the system simultaneously measures strain, temperature, and acoustic fields with high resolution and high sensitivity, and is scalable for multipoint sensing in more complex structures. The optical sensor-controller system advantages are low cost, low-power, light weight, easy installation, EMI immunity and ability to multiplex multiple sensors. The product is targeted to be retrofitted on board aging mission critical aircrafts and ships for load /crack detection and monitoring.


Tremendous needs exist for continuous real-time health monitoring for use in Department of Defense’s (DoD) advanced platforms and critical structures. Many of the DoD's aircrafts and ships currently in use are older than the pilots and crews that support them. For example, the Navy still operates over 100 P-3 Orions with an average age of over 30 years. The P-3s have logged about 16,000 flight hours on average-- more than twice the flight hours it was originally designed for. Continuous monitoring for structural integrity of DoD's aging fleet and other DoD critical structures is a major challenge.

For real-time health monitoring, only a few techniques are considered sufficiently technically mature for use in DoD's advanced platforms. Acoustic emission (AE) measurement is one of the few techniques considered technically matured to be deployed to detect the presence of active cracks, ultrasonic stress waves spontaneously emanating in all direction. Conventional AE monitoring uses piezo-electric (PZT) sensors to detect these active crack formation and propagation stress waves with high signal to noise advantage, but with many disadvantages; size and weight, heavy cabling, low heat resistance and susceptibility to Electromagnetic Interference (EMI).

Newly developed fiber optic (FO) sensors based on fiber Bragg grating technology offers many advantages over PZT sensors. FO sensors are very small, low cost, lightweight, easy to install, high temperature tolerance, EMI immunity and able to be multiplexed to provide effective condition health monitoring of current and future aircraft structures. The new compact optical fiber Bragg grating sensor array and interrogation system is able to simultaneously measures strain, temperature, and AE with high resolution and high sensitivity, record load history and detect cracks and corrosion in large aircraft structures cost effectively in real-time.