Control method of full index parameters for meter-level space aspheric mirror

Meter-level aspheric mirrors are the core optical products in space optical remote sensors. With the development of space optical remote sensing technology, the mirror manufacturing quality have gradually evolved from focusing on some key parameters in the past to global control of full index parameters. This is undoubtedly bringing great challenges for optical fabrication and testing. Taking a typical meter-level aspheric mirror as an example, the article introduces a full-parameter process control method for aspheric mirrors for space applications. First of all, in the aspheric surface shape milling and grinding stage, the contour measurement method is used to initially control the radius of curvature of the mirror surface, the aspherical surface coefficient, the effective aperture and the deviation of the optical axis; secondly, after entering the rough polishing stage, the mirror surface is quickly improved at the same time as the roughness index of the mirror, it improves the accuracy of the mirror surface shape and controls the mid-to-high frequency error. Finally, in the fine polishing stage, the method of gravity unloading is used to acquire the zero-gravity surface shape of the space mirror. The geometric and optical parameters of the mirror converge to the expected value, of which the error of the vertex curvature radius is better than 0.5mm; the error of the aspherical coefficient is better than 0.01%; the deviation of the optical axis is better than 1′/ 1mm, and the rms of the surface shape accuracy in the whole frequency band is better than 10nm, the low-band error is better than 8nm, and the mid-band error is better than 3nm; the surface roughness rms is better than 1nm, and the remaining parameters meet the needs of camera on-track applications. The proposed process control method has been expanded and can also be applied to high-precision manufacturing of aspheric mirrors in the range of 1-4m.