Research On The Key Technology For The Improvement Of The Figuring And Finishing Of Aluminum Alloy Mirror

Along with the increasing national demand for low orbit optical satellites,the existing manufacture process has many shortcomings such as low efficiency,high cost and high time cost,which seriously reduce the cost-effectiveness of load developing.To reducing the manufacture cost of money and time for small aperture mirrors,the key technology for the manufacture of metal mirrors will be studied in this paper.Aluminum alloy mirrors for infrared optics can be directly obtained through single point diamond turning(SPDT).However,to achieve higher bandwidth expectations,in classic manufacture process,aluminum alloy mirrors need electroless plating with nickel-phosphorus(N i-P)after SPDT.What's more,the N i-P layer need to be diamond turned once more to keep uniform thickness.In the end,an optical surface with higher procession and lower roughness could be achieved through polishing procedure.Neverthe less,the classic manufacture process has some inevitable problems,for example,the mismatch of the coefficient of linear expansion between the N i-P layer and the substrate could cause bi-metal bending effect,double SPDT will increase the cost and the co mplexity of the manufacture process.An advanced manufacture process,in which the aluminum alloy mirror surface is directly polished,is a key resolution.The key technology for the advanced manufacture process will be studied in this paper.The paper will be organized in four parts:1.The on-machine error sources during SPDT.It is different from the traditional computer controlled optical surfacing(CCOS),such as small polishing tools,magnetorheological finishing and ion beam figuring,that optical surfacing through SPDT could get much higher figuring efficiency and convergence efficiency of the form error.To make the manufacture process much more efficient,the error sources during SPDT should be analyzed.The on-machine errors could be divided into three parts—system error,artificial error,random error.2.The measurement and compensation of the machine system errors.The machine system errors contain linear error,perpendicular error,spindle rotation error,etc.During rotation the air bearing spindle could get a temperature rise.By constructing a temperature measurement system together with high precision capacitive displacement sensors,errors which are introduced by the machine system errors and the heat effect could be measured and then compensated in turning process.3.On-machine measurement system using capacitive displacement sensors.Capacitive displacement sensors have characters like high precision,high bandwidth and no time delay.Taking advantage of these characters,an on-machine measurement system using capacitive displacement sensors was constructed to realize efficient on-machine measurement of form error after SPDT.The measurement result could be used to modify the cutting tool path and makes the form error converge in high efficiency.4.Suppression of the mid-high frequency form errors after SPDT through chemical mechanical polishing with non-Newton fluid lap.Non-Newton fluid lap polishing is a new polishing method which ba lances the advantage and disadvantage in traditional CCOS.The non-Newton fluid lap polishing method exhibit both rigid and compliant characters.Through a modified time-dependent smoothing effect model combined with chemical mechanical polishing method,s uppression of the mid-high frequency surface form error after SPDT could be realized.