Introduction: Michelson Interferometer Build From LEGO(R) Bricks
A low-cost, full functional Michelson interferometer with nanometer precision is build on a honey-comb optical breadboard, all constructed from LEGO(R) bricks. The installation demonstrates a creative approach of open hardware for young researchers in the field of optics and photonics.
Attached is the LEGO(R) Digital Designer file, that contains the complete construction of the Michelson Interferometer.
Step 1: Setting Up the Optical Breadboard
The base of any of our optical setups is the optical breadboard.
The optical breadbroad is designed to fulfill a variety of features (that you may not recognize from the
- it offers a multitude of attachment points for your optomechanical components
- the attachment points are arranged periodically in two dimensions; thus the positioning of optomechanical components becomes rather simple
- it features a huge mechanical stability (that can not be said from the original LEGO(R) baseplates, themselves, that are highly flexible and definetely not suited for optical setups)
- it reduces significantly external vibrations and mechanical motions; thus, it is optimal for the setup of interferometers
HOW IT WORKS
The interieur of the optical breadboard is constructed having the honeycom structure in mind. This is common for professional breadboards and optical tables (compare with tables from newport.com or thorlabs.com or tmc.com).
CHALLENGE OF CONSTRUCTION
LEGO(R) bricks are designed to build parallelly or orthogonally on each other; for the breadboard, particularly its honeycomb strucutre, it is inevitably necessary to build with a mutual angle of 60 degree between two layers. At the same time, due to the dimensions of an optical breadboard (0.4 x 0.8 m^2), a multitude of bricks is required, that therefore shouldnt either be too expensive or unavailable from the brick shop.
We have choosen standard LEGO(R) bricks for the construction and found a layer-to-layer-concept that was capable to fulfil the demands: 1st row is parallel to the long side of the baseplate, 2nd row is rotated by +60 degree, 3rd row again is parallel to the long side of the baseplate, 4th row is rotated by -60 degree. The 5th row, again is parallel to the long side of the baseplate - then the top plates can be simply added.
Such concept requires at least 5 layers to end up with a complete honeycomb structure; larger thicknesses can be realized by adding at least two more layers (and manifolds of it).
We recommend sizes of the breadboard with a side ratiio of 1:2. Also, it is quite simple to start with (at least) two LEGO(R) baseplates, as it is demonstrated here in the video.
Step 2: Setting Up the Optomechanical Components
This video shows the construction of any single optomechanical component of the Michelson interferometer.
The heart of the setup is the mirror mount, that obeys two.axis adjustment with high precision and mechanical stability.