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To the best of our knowledge, we propose the first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL). Unlike prior analyzers that require profiling the beam at multiple locations along the light propagation axis, the proposed analyzer profiles the beam at the same plane for multiple values of the ECVFL focal length, thus eliminating beam profiler assembly motion. In addition to measuring standard Gaussian beam parameters, the analyzer can also be used to measure the M(2) beam propagation parameter of a multimode beam. Proof-of-concept beam parameter measurements with the proposed analyzer are successfully conducted for a 633 nm laser beam. Given the all-digital nature of the DMD-based profiling and all-analog motion-free nature of the ECVFL beam focus control, the proposed analyzer versus prior art promises better repeatability, speed, and reliability.

A wavelength-tuned signal-processing approach is proposed for enabling direct unambiguous temperature measurement in a free-space targeted single-crystal silicon carbide (SiC) temperature sensor. The approach simultaneously exploits the 6H SiC fundamental Sellmeier equation-based wavelength-sensitive refractive index change in combination with the classic temperature-dependent refractive index change and the material thermal-expansion path-length change to encode SiC chip temperature with wavelength. Presently, the technique is useful for fast coarse temperature measurement as demonstrated from room temperature to 1000 degrees C using a 10-peak count wavelength-tuned measurement with a 0.31 nm total wavelength change. This coarse technique can be combined with the previously presented two-wavelength signal-processing temperature measurement approach to simultaneously deliver a wide temperature range and a high-resolution temperature sensor. Applications for the sensor range from power plants to materials processing facilities.

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Accuracy, reliability, and long lifetimes are critical parameters for sensors measuring temperature in gas turbines of clean coal-fired power plants. Greener high efficiency next generation power plants need gas turbines operating at extremely high temperatures of 1500°C, where present thermocouple temperature probe technology fails to operate with reliable and accurate readings over long lifetimes. To solve this pressing problem, we have proposed the concept of a new hybrid class of all-silicon carbide (SiC) optical sensor, where a single crystal SiC optical chip is embedded in a sintered SiC tube assembly, forming a coefficient of thermal expansion (CTE) matched all-SiC front-end probe. Because chip and host material are CTE matched, optimal handling of extreme thermal ramps and temperatures is possible. In this article, we demonstrate the first successful industrial combustor rig test of this hybrid all-SiC temperature sensor front-end probe indicating demonstrated probe structural robustness to 1600°C and rig test data to ∼1200°C. The design of the rig test sensor system is presented and data are analyzed.