For looking at really small stuff, an optical microscope will only go so far. Looking at things at the nanometer level, though, usually requires some sort of electron microscope, with all the hassle of vacuum chambers and high voltages. There is another way to investigate the domain of the very small: an atomic force microscope. Unlike their electron spewing brothers, they don’t require high voltages or hard vacuums. They can also be built for about $1000, as [whoand] over on the Instructables shows us.
Instead of shooting light or electrons at an object and picking up the reflections, an atomic force microscope drags a very, very tiny stylus across an object. This stylus is attached to a probe that will reflect laser light off of it into a photosensor, eventually rendering an image on a display. [whoand] is using a laser diode and pickup unit from a DVD-ROM drive for the optical pickup unit, a frame made from soldered together PCBs, and a few piezos to vibrate the probe.
The probes themselves are incredible pieces of engineering with a tip size of a few nanometers. They’re consumable, and expensive, ranging from $20 to $500 per probe. Still, with these probes, [whoand] can look at the pits in a CD or DVD, measure the surface of an eraser, or check out the particulate matter floating around in the atmosphere in Beijing.
Thanks [Rob] for the tip.
[Matthew] got himself into a real pickle. It all started when he was troubleshooting a broken Hewlett Packard 8007A pulse generator. While trying to desolder one of the integrated circuits, [Matthew] accidentally cracked it. Unfortunately, the chip was a custom HP Pulse shaper IC – not an easy part to source by any means. That broken chip began a 5 year mission: to explore strange new repair methods. To seek out new life for that HP 8007A. 
