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Nano-meter precision positioning

Positioning something at the sub-micron level has a lot more involved than might be immediately apparent.  Variations in temperature, the room and foundation, even movement around the area can cause variations in equipment that is more than a few nano-meters, and that’s just for one axis of motion.  This makes it amazing that Alio Industries has managed to combine 3 axis of motion in their Hybrid Hexapod and get a repeatability of less than 10 nanometers!  (That’s positioning in all 3 dimensions, most manufacturers only work in 1 or 2).  You can check it out on their website.

So how can you increase the repeatability of your system?

1. Mount it on an extremely stable surface, granite is a popular choice.

2. Temperature control the room.  A few degrees may not seem like much on everyday systems, but the expansion and contraction of all the parts can add up rapidly when nanometers is the goal.

3.  High resolution position feedback, either extremely high line count encoders, lasers, there are some other options out there.  It is vital to know where the system is located as precisely as possible.

4.  The mechanical parts must be extremely high precision, not only in the dimension of travel, but if the travel surface has a wave, or imperfection, it can throw off the positioning in the other two dimensions as well.