Removal-angular-spectrum-guided targeted notch matching for suppressing MSF errors in oblique-incidence MJP

Magnetorheological jet polishing (MJP) is a high-precision deterministic sub-aperture technique for optical surface finishing. Oblique jet incidence is used for edge correction and for regions where normal-incidence polishing is constrained, causing the tool influence function (TIF) to evolve from an approximately rotationally symmetric morphology into a non-rotationally symmetric one. This non-rotational symmetry makes the TIF spectrum direction dependent and introduces local low-response regions that can be used to suppress path-induced periodic mid-spatial-frequency (MSF) errors. In this study, a removal-angular-spectrum-based path-parameter planning method is proposed for oblique-incidence MJP. TIFs obtained at different incidence angles are transformed into removal angular spectra, from which the characteristic notch angle and characteristic frequency are extracted as a targeted notch parameter pair and mapped to the path angle and path spacing. To improve practical applicability, machine-tool motion errors, metrology bandwidth, and path-dynamics constraints are incorporated into an engineering-effective angular-spectrum model. Single-point polishing experiments verify the incidence-angle-dependent evolution of non-rotationally symmetric TIFs, and cross-validation machining experiments on planar optical surfaces demonstrate that matching both path angle and path spacing to the corresponding angular-spectrum notch effectively suppresses periodic MSF errors. The results further show that simply reducing path spacing does not necessarily improve MSF-error suppression, establishing a local path-planning basis for future extension to curved optics with spatially varying TIFs.