Here's a small example of some of the focus stacking equipment developed over the years, and some of the necessary lightning strobes. These strobes were positioned by the "C Stands" to get the proper lighting, which at higher magnifications requires massive amounts of light. The focus stacking fixtures are for vertical and horizontal use, and some have X, Y, & Z for Stack and Stitch efforts, automated controllers based upon the Trinamic Devices were developed for stacking and S&S efforts.
This is the kind of effort required when your imaging chips that get blown up very large, sometimes covering a large wall. We started these efforts back in 2000 using the usual shooting thru a microscope, but soon realized the limitations and decided to develop our own lens, fixtures and controllers. Quite an undertaking back then and evolved into these type of fixtures and setups.
One very difficult obstacle that showed up was flip chip solder balls. When these are new and not oxidized, the surface is like a tiny 40~100um polished spherical mirror that reflects everything from everywhere!! Another was the perspective change when stacking and especially when S&S when you are trying to line up 19 tiles, each tile stacked with 300~400 individual image (yes 6,000~8,000 images) to render a final image of 30,000 by 25,000 pixels!! Because chips have precise features that must line up perfectly when stacking and especially when stitching, this calls for a different type lens design called "Telecentric", where the apparent magnification doesn't depend on distance to subject. This is just scratching the surface tho, lots of interesting challenges encountered!!
Anyway, fun stuff indeed!!
Best,