Composite strengthening technology based on surface prestressing and microcrack healing of Micro Pore Optics

Abstract Micro Pore Optics (MPO) is a kind of ultra-thin spherical glass material featuring microporous array structure, which is composed of millions of micron-sized channels precisely arranged along the spherical radius direction. The inner walls of these microchannels exhibit high reflection to ultraviolet light, enabling the focusing and imaging of ultraviolet light from different directions onto the distinct positions of the focal plane to achieve spatial resolution. Since the spherical microporous structure has no fixed optical axis, there is no off-axis aberration when using MPO for imaging, and it can be infinite splicing to achieve a large field of view for detection. MPO has the characteristics of large field of view, high detection efficiency, superior resolution accuracy, compact size, light weight, etc., and is widely employed as an optical window for space-based Ultraviolet detection, playing an important role in the field of aerospace and other major scientific research equipment. However, because that the working environment is often accompanied by vibration and shock, and MPO is an ultra-thin sheet of glass material with a porous structure, the mechanical strength has been a bottleneck in the application of MPO. In view of the technical problem of low mechanical strength of MPO, the study was carried out on the composite strengthening technology based on the surface prestressing and microcrack healing of MPO. The effects of the reaction temperature, the reaction time, and the film thickness, the deposition temperature and other parameters on the strengthening process were systematically studied in this investigation. The composite strengthening technology was combined with the following process in sequence: the first reaction with Na + /K + molten salt for 2 h at 350°C, then deposition of Al2O3 film with a thickness of 100 nm at 200°C, and finally high temperature annealing at 500°C for 0.5 h in nitrogen atmosphere. A strength enhanced MPO with bending strength of 69 MPa and elasticity modulus of 27 GPa was obtained, which meets the application requirements of vibration and shock resistance, and provides an important reference for the scientific research and application of ultra-thin porous glass materials.