automatic point counter

views updated

automatic point counter An electronic control panel designed to count the number of times a particular mineral is recorded on multiple, closely spaced traverses of a thin section viewed down a polarizing microscope. The control panel, which contains a bank of recording buttons, each assigned by the user to a particular mineral, is linked to a thin-section holder mounted on to the stage of a polarizing microscope. The holder is designed to move the thin section by a predetermined distance (variable from 0.001 to 1 mm) in one direction, after the user has pressed the control panel button assigned to the particular mineral observed under the eyepiece cross-wires. At the end of a complete traverse, the holder automatically resets by a predetermined distance to start the next traverse. On completion of all the traverses, the control panel shows the number of times each mineral was recorded and can recalculate this as a percentage of the total number of points. This gives the percentage volume of each mineral recorded in the rock.

About this article

automatic point counter

Updated About encyclopedia.com content Print Article