A precision scan sphere designed for use in conjunction with scanner technology, and includes a full or partial sphere, having a laser detecting surface, and which can be mounted by a shank into a holder, or held by a steel insert that may be applied to a sphere mount, during its application and usage. The mixed modulation memory access circuit selectively accesses burst memory locations containing a valid burst of coded bits. An expandable capture basket may be disposed near the end of the low pressure lumen. The prism element includes a groove formed in the second substrate.