ACute3D: A Compact, Cost-Effective, 3-D Printed Laser Autocollimator

The ACute3D is a compact laser autocollimator, capable of precise angle measurement in two orthogonal directions over a maximum measurement range of
$7200\times5300$
arcsec. The measurement uncertainty over the middle third of its range is less than 3 arcsec. Our novel design exploits the geometric freedom of fused filament 3-D printing to realize a monolithic optomechanical assembly. The monolithic block makes the instrument compact, lightweight, stiff, and resistant to drift, as well as minimizing alignment during assembly and minimizing cost. Our openly licensed design together with our use of digital fabrication makes this autocollimator convenient to customize or integrate into larger instruments. The total bill of materials cost is around ￡200, making precise angle measurement available in a wide range of contexts. We demonstrate an application of the ACute3D by measuring the angular deviation of a precision linear stage, showing that our design is ready for typical laboratory use.