| Aero-optical effect induced by the supersonic flowfield around optical dome is a key factor that affects its guidance accuracy. Mechanism study about it not only helps us understand the relationship between flow structures and the corresponding aero-optical aberrations, but also supplies important theoretical basis for aero-optics control to improve aero-optical performance.Experimental study of the aero-optics mechanism of the supersonic flow around optical dome faces several difficulties: (1) How to produce supersonic flowfield for aero-optics mechanism study avoiding the influences from free stream noise on aero-optics tests; (2) There are shock waves and turbulent boundary layers in the supersonic flow around optical dome. How to measure the flow structures at high spatiotemporal resolution; (3) How to extract the density field at high spatiotemporal resolution from the experimental data of fine flow structures; (4) How to calculate the aero-optical aberration from the known density field and how to construct the relationship between aero-optical aberration and flow structures; (5) How to improve the flow-following performance of DPIV (Digital Particle Image Velocimetry) tracer particle in supersonic flow and improve the accuracy of the cross-correlation algorithms for supersonic flow. To overcome these difficulties, several innovative methods and techniques with high performance were proposed in this thesis to study the mechanism of aero-optical effects and fine structures of supersonic flow around optical dome.Considering the requirement of aero-optics mechanism study on the quality of free stream, a supersonic wind tunnel that could produce free stream of low noise and turbulivity was designed in this thesis, and its configuration is suitable for optical non-intrusive tests. For the existence of shock waves and turbulent boundary layers in the supersonic flow around optical dome, the measurement technique should have high spatiotemporal resolution and ability to measure 3D complex supersonic flow field. NPLS (Nanoparticle-based Planar Laser Scattering) is a new technique to measure fine structure of supersonic flow, and can visualize temporal correlation instantaneous flow structures of a section in supersonic 3D flow field. Fine structures of flow field around optical dome were studied using NPLS in this thesis, and the NPLS images revealed fine structures of the flowfield, such as shock waves and turbulent boundary layers, and temporal correlation NPLS images revealed the temporal evolution of the flow structures. To study the temporal evolution of aero-optical aberration induced by the supersonic flow around optical dome, its velocity field was studied using DPIV in this thesis. The DPIV system in this thesis employed nanoparticle as tracer particle, for its excellent flow following performance in supersonic flow. Synchronizer at high accuracy, laser with high pulse energy, and several algorithms of high accuracy were employed to improve the measurement accuracy. The velocity field around optical dome was studied using this DPIV system, and the results revealed the velocity field faithfully.NPLS images of the supersonic flow around optical dome revealed its density field qualitatively. However, how to extract the density field quantificationally from NPLS images to calculate the corresponding aero-optical effect is a problem to be solved urgently. A new technique for measuring supersonic density field, called NPLS-DT (NPLS-based Density Technique), was proposed in this thesis in a creative way. After removing the influence from background, nonuniform distribution of laser sheet intensity, and some other factors, the relationship of NPLS image gray and local density was estimated by oblique shock wave calibration, and then the density field around an optical dome could be measured quantitatively. The density field measured by NPLS-DT had high spatiotemporal resolution and revealed fine flow structures, and temporal correlation results revealed the temporal evolution of the density field.After measuring the density field around optical dome using NPLS-DT, adopting Ray-tracing theory, a new wavefront measurement technique named NPLS-WT (NPLS-based Wavefront Technique) was proposed in this thesis. NPLS-WT has three obvious advantages: it has high spatiotemporal resolution, and can study the flow field of interest locally avoiding the integral effects of other methods, and can avoid the influence from the wind tunnel boundary layer and circumstance. After measuring the aero-optical aberration induced by the flow field around optical dome, multiresolution analysis and fractal analysis were adopted to study the aero-optics mechanism of the supersonic flow around optical dome: (1) The contributions from various flow structures to the wavefront were analyzed: shock waves and expansion waves could incline the wavefront, and the large-scale structures in turbulent boundary layer only affect the wavefront locally; (2) The results of multiresolution analysis revealed that the wavefront in near field is not sensitive to the resolution, and large-scale structures play a dominant role on the wavefront in near field; (3) The analysis results on the frequency of aero-optical aberration revealed that its frequency is so high that the adaptive optics is not available nowadays, and the aero-optical performance of supersonic optical dome can be improved by optimizing the geometry of the optical window and restraining the generation of the large-scale structures. (4) Fractal analysis of wavefront shows that the small-scale wavefront behavior depends strongly on the anisotropy parameters. There exists a particular value of the anisotropy parameter for which the small-scale wavefront structure is found to be scale independent over a range of scale. To compare the aero-optical performances of supersonic optical dome in different conditions, the averaged flow field around it was simulated numerically and the corresponding wavefront was calculated, and then analyzed the relationship between wavefront aberration and the attack angle, and the Mach number of free stream.Based on BOS (Background Oriented Schlieren), a new wavefront sensing technique, which is called BOS-WT (BOS-based Wavefront Technique), is proposed innovatively in this thesis, and can be used to study 2D wavefront. It has high temporal resolution and temporal correlation resolution. Instantaneous wavefront passed through the supersonic flow field around optical dome was studied by BOS-WT, and the temporal correlation wavefront revealed the temporal evolution of the distorted wavefront.
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