Two-dimensional surface temperature diagnostics in a full-metal engine using thermographic phosphors

An optical system consisting of a rigid borescope was developed to measure surface temperatures inside full-metal internal combustion engines. The measurement principle is predicated on lifetime-based phosphor thermometry of the material Gd 3 Ga 5 O 12 : Cr. The system is designed to resolve the luminescence decay of thermographic phosphors temporally and two-dimensionally by the use of a CMOS high-speed camera. The device allows the visualization of the temperature distribution in an area of 9 mm in diameter. An application of this optical system inside an internal combustion engine is demonstrated, yielding temperature maps under fired and motored conditions in a full-metal engine for the first time.