Aero-optical effects of an optical dome with a supersonic film cooling at various wavelengths

Hypersonic optical domes experience intense aerodynamic heating in atmospheric flight. The application of supersonic film cooling to a window is an effective thermal protection method; however, due to aero-optical effects, an optical dome still faces challenges in achieving clear imaging for targets. Investigation of the influence of wavelength on imaging quality is essential to enhance the accuracy of imaging-guided systems. In this research, an aero-optical measurement platform was established in a Mach 6.0 hypersonic shock wave tunnel to measure the aero-optical wavefront of an optical dome with Mach 3.2 supersonic film cooling. As the wavelength increased, the Strehl ratio and the imaging integral resolution both increased significantly. Compared to the condition without film cooling, the imaging integral resolution of the optical dome with supersonic film cooling decreased by ∼30%, and the spatial complexity of the aero-optical wavefront increased. These results had a negative influence on the imaging quality of the hypersonic optical dome. Within the diffraction limit, it was confirmed that the imaging quality could be improved with the increase in the light wavelength. Compared with visible imaging, infrared imaging was less affected by aero-optical effects.