Integrating Fiber Fabry-Perot Cavity Sensor into 3-D Printed Metal Components for Extreme High-Temperature Monitoring Applications

This paper reports the methods of embedding into 3-D printed metal components a fused silica capillary designed to accept an in-fiber Fabry-Perot cavity-based extreme high-temperature sensor. The components are manufactured in stainless steel (SS316) by additive manufacturing using selective laser melting (SLM). The temperature sensor consists of a standard single-mode optical fiber with the F-P sensor located at the distal end of the fiber with the fiber being inserted into the capillary. The capillary is either directly embedded into the structure during the SLM build process or brazed into the structure in between the SLM build process, and the advantages and disadvantages of these two manufacturing approaches are discussed. Temperature sensing of up to 1000 °C inside the metal with an accuracy better than ±10 °C is reported. The capillary can be directly embedded in the component, which needs to be monitored, or it can be embedded in a metal coupon, which can be attached to a component by conventional welding technology, including the use of laser metal deposition (LMD). In the case of LMD, the sensor coupon can also be fully encapsulated by over cladding the coupon.