An accurate extraction method of HTV signal based on Hessian matrix optimization algorithm

The shape of OHp tagging signal line is complicated and changeable under the interaction of turbulence and combustion in HTV velocity measurement of scramjet combustion flow field. The light intensity distribution on the OHp tagging line is modulated, and the broadening degree is not consistent with the Gaussian distribution, so an optimal extraction method based on Hessian matrix is presented. Using the Hessian matrix, the gray distribution function on the cross-section of the tagging line is expanded in the normal direction by the second-order Taylor, and the precise position of the center line is obtained. Compared with line-by-line Gaussian fitting method, this method has better anti-distortion and anti-noise performance. The accurate extraction method of OHp molecular information is applied to the HTV velocity measurement technology in the scramjet combustion flow field, which improves the precision of the extraction and the accuracy of the HTV velocity measurement. It lays a foundation for the development and application of HTV.