Method, apparatus, and computer-readable medium for reduced error in positional repeatability

An apparatus comprising:

• (a) 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;
• (b) a first 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 first drive;
• and
• (c) intermediate drive components comprising a band and two separate rotatable members, wherein the intermediate drive components are separate from the first drive and engagedly coupled between the rotatable element and the first drive, wherein one periodic cycle of the rotatable element is an integer number of periodic cycles of the at least one of the intermediate drive components, and wherein the separate rotatable members are coupled by the band, and wherein one periodic cycle of the rotatable element corresponds to a first integer number of cycles of the first drive and a different second integer number of cycles of the band.