NASA/ Marshall Space Flight Center (MSFC) needs sensors that can be operated on rocket engine plume environments to improve NASA/SSC rocket engine performance. In particular, NASA/MSFC would like to develop sensors to monitor the performance of rocket engines. The measurement of soot volume fraction and soot particle size can be employed to develop a sensor for on-line, real-time measurements to characterize the performance of hydrocarbon rocket engines and study the effects of the rocket engine exhaust on the environment. The goal of this proposed effort is to develop a laser-induced incandescence (LII) sensor, which is able to provide near real time measurement of soot concentration in the engine plume. During Phase I, a LII system based on telescopic collection optics for remote applications will be designed. The experimental parameters will be evaluated to achieve optimum response time and sensitivity. The study from Phase I will provide the necessary information to improve the phase II prototype design to achieve millisecond response time and better sensitivity. In Phase II, a prototype fieldable LII system will be developed and tested at MSFC and will be delivered to NASA/MSFC for further testing.