This invention is related to an automatic self-service vision screening kiosk and method that allows individuals to screen their eyesight without assistance. A shielding arrangement, located between the dispersive element and the ion deflector is arranged to define the portion of the beam to be deflected by the ion deflector. A light source is mounted to the housing in a fixed position and a length of optically conductive material extends from within the toggle to adjacent the light source, such that, when the light source is on, light is visible through the toggle via the optically conductive material. A monitor unit determines that the VCT phase has passed through the intermediate lock phase when the lock request occurs before completion of learning of the reference phase, and when a change in the VCT phase becomes greater than a threshold. A plurality of first screws extends through the LED modules and the plate to secure them together, while a plurality of second screws extends through the plate, the cover and the housing to fix the whole LED unit to the housing. The second polishing pad has at most a deficient content of prior accumulated concomitant CMP residue, e.