The Design Of Inductively Coupled Plasma Jet Processing System For High Power Laser Optics

In the Inertial Confinement Fusion system, large-aperture aspheric opticalcomponents are widely used, which can effectly eliminate coma, sphericalaberration, astigmatism, and curvature of field and distortion. Moreover, reducationof energy loss and high quality optical characteristic are achieved. Specifically, inthe Final Optics Assembly(FOA), the Wedged Focus Lens is designed to provide thefunction of color seperation, after KDP tripler at the target via lateral dispersion.Howerver, the design of wedge aspherical non-symmetrical features makes itdifficult for the fabrication and polishing process. After the stage of ultra-precisiongrinding, sub-surface damage layer about20m thickness will be induced on theoptics, which is extremely unfavorable for the subsequent polishing process. First ofall, fused silica material is difficult to polish for the hard and brittle characteristics.Traditionally, asphalt disc polishing process is unacceptable because of its lowefficiency and disruption of form accuracy. Thus, inductively coupled plasmaprocessing under atomspheric pressure is proposed as a non-contact solution topolish silicon-based material. Based on the chemical reaction, no sub-surfacedamage will be induced to the optics after processing.In the paper, according to features of inductively coupled plasma and wedgedfocus lens, a series of systematic design work are conducted for the plasmaprocessing apparatus. Mechanical system design and analysis, numerical controlsystem design, plasma polishing algorithm and study on verification test, are fullydiscussed.First of all, a hybrid five-axis machine is designed to fabricate the complexaspheric optical surfaces. In the part, the kinematics of mechanism is described,including inverse kinematics calculation, work space analysis. Then, detailedstructure of the machanical system is designed and analyzed using FEM.Secondly, in terms of hardware and software, an open numerical control systemis designed. The chapter describes the overall structure of the inductively coupledplasma CNC system. Then, several functional modules of inductively coupledplasma CNC system are discussed in detail.Finally, the research of plasma polishing algorithm and related study onverification tests are conducted. Based on the mathematical model, the principle ofcomputer-controlled polishing is explained. In the perspective of linear equationsand image restoration, polishing algorithm is realized respectively. Verification testsare conducted and prove that the inductively coupled plasma is fit for conformal polishing.