Development of a new fiber-optic multi-target multispectral pyrometer for achievable true temperature measurement of the solid rocket motor plume

This paper describes the development of a novel multi-target multispectral pyrometer to remotely measure the true temperature of the plume of a solid fuel rocket engine in a harsh environment ground test. Using an optical fiber transmission technique, the core part of the instrument can be located 100 m away from the test site, so the influence of the harsh environment can be reduced and the instrument reliability improved. Optics are separated from prisms to accurately locate targets. Based on preamplifier circuits and parallelly adjacent pixels of the photodiode detectors, the measurement lower limit can reach 900 °C. The pyrometer is validated against experimental data from field measurements of a solid fuel rocket motor plume. The results demonstrate that the true temperature of the solid fuel rocket engine plume can be acceptably measured with the proposed pyrometer.