3D Printed Optics 2: Precision Translation Stage
Updated: Mar 9
In the last 3d printed optics post I showcased my mounts for rotating optics with good precision, but sometimes optics need to be moved precisely, and this is where 3d printed linear adjusters come in. I took the design from an existing precision linear stage and modified it to be easily made on a 3d printer. The core of the mechanism is a trapezoidal rail and carriage which is threaded for an m3 screw. Missing from the CAD is a compression spring which adds preload on the carriage to keep it in place.
To 3d print these it took some trial and error to get the right tolerance in the rail, but these are small parts so this does not take long.
Once printed the rail is assembled by glueing the head onto an m3 bolt, threading it onto the carriage and adding a small amount of grease. The stage has around 40 mm of travel in total and the m3 thread gives 500 um of displacement for each rotation so in practice you can almost move parts to 10 um. That is around the thickness of a human hair!
For how simple these parts are they actually perform really well!
I tried to see this by mounting calipers up on an optical bench and measure how fine I could adjust the position.
Plastic is far from the ideal material here but for many applications this is absolutely perfect. One example is my acoustic levitation project, an upgraded version used much greater acoustic power but the distance between the transducers had to be adjusted precisely. Since the length of the acoustic wave was almost 10 mm the precision of this stage is more than good enough, even taking thermal expansion into account.
Tuning the distance between the transducers I found that I could levitate a droplet of water and get it to spontaneously form into a bubble. This was actually only discovered in 2018 and got published in nature!! But that is a topic for another post.
So in conclusion these 3d printed rails are quite capable, and the thread on top also allows me to attach the previous optic mount onto the moving stage, adding even more degrees of adjustability.