20150268440 | METHOD, APPARATUS, AND COMPUTER-READABLE MEDIUM FOR REDUCED ERROR IN POSITIONAL REPEATABILITY - Presented is a method, apparatus and computer-readable medium for reducing error. The apparatus includes a rotatable element having a plurality of spaced light modifying ports located at set positions in the rotatable element, the rotatable element rotatable about an axis. The apparatus further includes a drive engagedly coupled to the rotatable element to rotate the rotatable element, wherein one periodic cycle of the rotatable element is an integer number of periodic cycles of the drive. | 09-24-2015 |