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HoloBox - Digital Holography and Interferometry

A fully open-source learning system for optics, interferometry, and holography.

The HoloBox is a modular, open-source toolbox that brings classical and digital optics experiments into classrooms, labs, and maker spaces. Built on the openUC2 cube system, it enables hands-on experiments ranging from Michelson/Mach-Zehnder interferometry to inline digital holography and lensless microscopy. The system combines precise optical hardware, open electronics, and modern digital workflows such as Jupyter notebooks, Python image reconstruction, and AI-ready embedded cameras.

The entire project is open-source: hardware, firmware, software, and teaching materials.

What You Can Do With the HoloBox​

The HoloBox enables a wide spectrum of optical experiments:

Classical Optics & Interference​

  • Build and align a Michelson interferometer
  • Explore the Mach–Zehnder interferometer
  • Perform double-slit and grating diffraction
  • Observe interference fringes, stability, drift, phase shifts
  • Observe temperature induced variations in the Michelson Interferometer
  • Reconstruct Inline Holography Microscopy/Digital Holography Microscopy (DHM) using a Raspberry Pi
  • Visualize thermal expansion by heating one arm of an interferometer

Digital Holography​

  • Capture inline holograms using a point source and the Raspberry Pi Camera
  • Reconstruct the hologram numerically using a Python-based UI or Jupyter notebooks
  • Perform digital refocusing, Fourier analysis, and phase retrieval (comming soon)
  • Understand the connection between physical waves and numerical propagation

Lensless Microscopy​

  • Image microscopic samples with/without an objective lens
  • Detect microplastics, plankton, or other transparent objects
  • Explore Fresnel propagation and digital reconstruction of real samples

Interdisciplinary Learning​

  • Combine physics with biology, environmental science, or computer vision
  • Use programmable electronics (LED modulation, heaters, piezo elements)
  • Learn scientific computing through interactive coding tasks

What’s Included in the Box​

The HoloBox comes in two modular versions. Schools, labs, and hackers can start with the Base Set and expand later with the Digital Extension.

1. Base Set – Interferometry & Wave Optics​

Includes everything needed for classical optical experiments:

  • Precision openUC2 injection-molded cubes
  • 50 mm optical rails & mounts
  • Front-surface mirrors
  • Beam splitter
  • Low-cost laser module
  • Screens for fringe observation
  • Apertures, slits, gratings
  • Worksheets / Wunderbooks
  • Printed build instructions

This set enables:

  • Michelson interferometer
  • Mach–Zehnder interferometer
  • Diffraction experiments
  • Basic holography (scratch holograms)

Inline Holography​

Reconstruction using the ImSwitch Inline Holography Plugin

Michelson Interferometer​

Mach Zehnder Interferometer​

2. Digital Extension – Holography & Computation (deprecated)​

The new computational part of the HoloBox is now integrated into the ImSwitch system. We decided to integrate a Raspberry Pi 5 overa a Raspberry Pi Nano to have better performance and capabilities.

For the legacy part, you can follow the custom Raspberry PI image here:

Adds the digital and computational layer:

  • Raspberry Pi Camera (smart camera that runs our dedicated Operating Sytsem)

  • Download the image from here and flash to the SD card https://github.com/openUC2/TechnicalDocs-openUC2-HoloBox/releases/

  • Electronics module for:

    • LED control
    • Thermal/piezo phase shifting
    • Triggering and syncing

  • Python and Jupyter notebook tutorials

  • Digital reconstruction workflows

  • Sample experiments (microplastics, plankton, etc.)

This set enables:

  • Inline holography
  • Hologram reconstruction
  • Lensless microscopy
  • Computational imaging
  • Integration into coding classes

Modularity & Open-Source Philosophy​

The HoloBox is fully modular and open:

  • All CAD files are openly published (STL/STEP)
  • Parts can be replaced or extended via 3D printing
  • Supported by a growing openUC2 community
  • Compatible with the UC2 miniBOX, coreBOX, and Quantum MiniLabs
  • Designed for repairability and long-term use
  • Firmware, software, workflows, and notebooks are open source

The goal: Make advanced optics accessible, affordable, and hackable.

Getting Started​

  1. Get your kits from openUC2 Write us a mail: purchase@openuc2.com - STP files will be shared once we're fully done with development

  2. Run your first experiment Choose between Michelson, Mach-Zehnder, diffraction, or holography.

  3. Connect the Raspberry Pi Camera (optional) Start capturing digital holograms or real-time interference patterns. Connect to the Wifi Hotspot (password: holobox123) and open the website http://192.168.4.1

  4. Open the Webiste Learn how to:

    • Load holograms
    • Reconstruct using Fresnel propagation
    • Perform digital refocusing
    • Visualize spacetime fringes and frequencies

  5. Modify & extend Print new modules, explore new samples, or write your own analysis scripts.

Documentation & Resources​

Links will be added once this repo structure is finalized.

Who Is Behind the HoloBox?​

The HoloBox is a collaboration between:

  • openUC2 GmbH – hardware, electronics, software & production
  • University of Münster – Institute for Physics Education – didactic design & teaching materials
  • Supported by regional & national STEM networks

Roadmap​

  • Additional digital reconstruction methods
  • Phase-shifting holography
  • Multi-wavelength illumination
  • Plugin for ImSwitch
  • Extended classroom activities
  • Community-submitted modules

License​

All hardware, firmware, and software are released under open licenses:

  • Hardware → CERN OHL / CC-BY
  • Software → MIT
  • Teaching materials → CC-BY