This research experiment recreates a quadrature Mach-Zehnder optical inferometer using Adafruit microcontroller for analog-to-digital data acquisition.

We report on the construction and characterization of a low-cost Mach-Zehnder optical interferometer in which quadrature signal detection is achieved by means of polarization control. The device incorporates a store-bought laser pointer, home-built photodetectors, 3D-printed optical mounts, a circular polarizer extracted from a pair of 3D movie glasses, and a Python-enabled microcontroller for analog-to-digital data acquisition. Components fit inside of a 12"x6" space and can be assembled on a budget of less than $500. The device has the potential to make quadrature interferometry accessible and affordable for labs, students, and enthusiasts alike.

Use the package manager pip to install all required libraries

pip install notebook
pip install numpy
pip install matplotlib
pip install pandas
pip install serial

1. Open Create_CSV.py file and check that USB port matches port that trinket is plugged into on computer. You can check this by using the terminal to check devices plugged into the USB ports, or you can use the Mu editor for coding the trinket. In Mu hover over the connection symbol in the bottom right of the window and it will tell the USB port the trinket is connected to.
2. Run Create_CSV.py first, if indexing error occurs on boot then run again until successful
3. Chose Animate_expansion.py, Animate_raw_signal.py, or Animate_lisafig.py and run to see realtime data
4. When done, quit Create_CSV.py and check to see that data.csv has been generated and updated
5. Run coefficient_of_thermal_expansion.py to generate graph

We utilized Mu Editor and edit our code in circuit-python.

Purchase the Trinket M0 microcontroller using this link.
Download the Mu Editor to interface with the trinket here.
After downloading Mu Editor connect Trinket to computer via USB and upload main.py to trinket and save.

Trinket M0 pin I/O diagram here.
connect the following components to the pins provided below.
Photodetector A:
Source: pin A3
Output: pin A1

Photodetector B:
Source: pin A0
Output: pin A2

LM35 Temperature Sensor:
Source: pin 3V
Output: pin A4

These are the obj files for our mounts (download).
When constructing the interferometer it is recommended that the 3D printed kinetic screw mounts are secured to the plate using expoxy rather than hot glue do the the elasticity of the glue. All other components do not need to be adjusted after initial application and should be secured with hot glue incase mirror alignment is off.