Petrog® point count stage photos

The PetrogLite system is a computer-controlled, 2-axis point count “stepping-stage”, made by Conwy Valley Systems, Ltd. It includes the stage and stage control software subset of their larger Petrog system. There are several things you can do with this stage, but its main purpose is to set up a grid of points on a rock thin section. Then, under computer control, it moves the stage to each grid point, where you tell the computer which mineral is under the crosshairs. You have 26 (or 52) keyboard letters, each of which can be assigned to a mineral. The software tally’s up the points and calculates a percentage of each, giving a mineral mode.

Here are the software installation instructionspoint counter installation guide, and software user manual. Go to Conwy Valley Systems, Ltd. for software updates.

Quick instructions here
Illustrated instructions here
Stage installation, this page

If you can’t find the point counter, it’s probably hiding inside this cute little box. The box will usually be stored in Olin 318, but expect it to travel.

This shows the controller box front. At least I think it’s the front. It has a pretty blue light on it that wouldn’t be much good on the back. The cable goes to the point counter.

This is the back of the controller box. It has no light, but it does have the off-on switch, a nice, blue USB cable that goes to the computer, and the stage power supply cable.

This shows the point count stage mounted on a microscope, with a big, 50×75 mm thin section in the clip. The holder can accommodate even larger sections, but actual rock blocks are probably too heavy, so don’t try those. The white Pac-man-like thing is an adapter for smaller, normal-sized thin sections.

This is a normal 27×46 mm thin section, with the Pac-man adapter in place. You can make other adapters to put odd-sized or shaped sections where you want them on the stage. The software can also accommodate round sections with a grid in a circle. There are many options like that which are omitted from these quick instructions.

This shows the underside of the point counter, loose mounting and alignment screws, threaded and unthreaded holes, and two installed pins. Pins and screws can be arranged to accommodate most microscopes. The screws are very tiny, and the smallest require the little Allan wrench to put in.

Note that the point counter has two identical sets of holes, allowing you to mount it in two different positions on the microscope stage, one close to the central hole, and one farther away, for different sizes or shape sections.