Exposure-Pattern Compensation in Vat Photopolymerisation: Optical Blur, Cure Spread, Geometry Bias and Model Transfer

Exposure-pattern compensation modifies the image sent to a vat-photopolymerisation system so that the manufactured geometry approaches a target despite optical blur, pixel cross-talk, thresholded polymerisation, cure spread, accumulated dose and deformation. The task is an inverse problem, not a universal XY offset. A pattern that corrects one feature size, resin or projector location can fail on another because the forward response depends on irradiance distribution, spectrum, layer history, resin state, geometry, support and metrology. Positive and negative features can exhibit different bias, and a lower mean dimensional error can coexist with closed channels, missing walls or unacceptable surface shape. This review defines a qualification framework for feed-forward pattern compensation in masked and projection vat photopolymerisation. It separates projector pixel pitch from measured optical response, optical blur from chemical cure spread and shrinkage, calibration from prospective validation, and geometry correction from deliberate property grading. Direct studies of pixel blending, mask planning, grayscale regulation, pixel-resolved solidification and model-based optimisation support the workflow. Filled-resin light-transport studies demonstrate why scattering must enter the forward model, but their optical parameters are not transferable. A defensible compensation therefore requires radiometry, point- or line-response measurement, feature-class-specific metrology, constrained inverse optimisation, uncertainty reporting and holdouts across location, geometry and process state. No universal point-spread kernel, edge offset, shrinkage factor, compensation image or accuracy improvement follows from the literature.