A LASER INTERFEROMETER MEASURES IN NANOMETERS - THIS ONE USES A 12 DOLLARS DIODE AND WINDOW GLASS
An open interferometer that measures like a 17,000 dollars metrology tool, built from window glass and a laser diode you can order today.
WorkshopScience
- difficulty
- ●●●●○
- time
- a weekend-plus
- license
- MIT
- repo
- repo ACTIVE141 stars
●●●●○ · a weekend-plus · MIT · 141 stars · repo ACTIVE
WHAT YOU’LL NEED
- 3D printer + filament — printable parts — files are in the repo
- Dev board / microcontroller — runs the project firmware
Partner
COMPAREE VERDICT
This is a genuinely impressive piece of open hardware: a Michelson interferometer built from parts that cost less than dinner, designed to reach the same nanometer-scale resolution as industrial laser calibration systems that start around 17,000 dollars. The core idea is sound — split a coherent laser beam, bounce the two paths off fixed and moving mirrors, then count the interference fringes as they recombine — and the execution is clever: the beam splitter is ordinary window glass ground optically flat in a 3D-printed jig, the laser is a 12 dollars Osram PLT5 516FA diode, and the photodiode detector costs about 70 cents. The build video walks through the mechanical assembly and optical alignment in detail, and every file is MIT licensed. The honest limitation is that this is explicitly a work-in-progress: the repository has FreeCAD models at Version 5, KiCad sources you export yourself, and no written BOM or step-by-step assembly guide. If you have never aligned optics or worked with coherent light, the video will not be enough. The single thing most likely to go wrong is grinding the glass beam splitter — optical flatness matters and there is no metrology in the repo to check it, so you are working blind until the fringes appear. If you are comfortable designing your own test setup and iterating on alignment, this is a remarkable foundation. If you need a parts list and a procedure, wait for the project to mature.
IN THE REPO
NOT IN THE REPO
- —FreeCAD mechanical models and KiCad electronics sources are in the repository, marked Version 5.
- —No bill of materials — part callouts are in the video and scattered across README sections.
- —KiCad source files only; you export Gerbers yourself.
- —No assembly guide or optical alignment procedure in writing — the build video shows it but there is no text walkthrough.
- —Project is marked work in progress and earlier design revisions exist; do not mix CAD versions.
- —MIT licensed, unrestricted.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Partner · KickstarterHeyGears G1: 10M+ colors and transparent parts in one print, plus UV printing on flat objects. Figures, parts and labels — no painting.
Videos
nmWave Interferometer Part 3 (build and alignment)
Shows mechanical assembly, glass grinding, and optical alignment; no narration, workshop footage only
Gallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Watch the build video to see the grinding jig and optical alignment in action (No written guide exists; the video is the primary documentation)
- 2.Clone the repository and open the FreeCAD models (Version 5) (Do not mix CAD versions — earlier revisions are in the commit history and dimensionally incompatible)
- 3.Export Gerbers from the KiCad photodiode and control board sources(Ready-made Gerbers are not provided; you generate them yourself)
- 4.Source the Osram PLT5 516FA diode and 3mm photodiode before printing anything(Part numbers are in the README; no supplier links or full BOM)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- The repository ships KiCad sources, not Gerbers — if you have never exported board files, that step alone can burn an afternoon.
- There is no written BOM: part callouts are in the video and README fragments, so you assemble the list yourself from multiple sources.
- Grinding the beam splitter to optical flatness is the hardest part and there is no metrology procedure in the repo — you will not know if it worked until you see fringes.
- The project is marked work in progress and the CAD is at Version 5; mixing files from earlier commits will give you mechanically incompatible parts.
- Optical alignment is shown in the video but not documented in text — if you have never aligned a Michelson interferometer, expect multiple attempts.
- The Osram diode is Class 3B; enclose the beam path and never work with the laser at eye level during alignment.
How does this compare to a Renishaw XL-80 in actual accuracy?
The repository does not publish test data or a comparison — the claim is nanometer-scale resolution because that is the theoretical limit of counting laser fringes, but environmental stability, thermal drift, and alignment quality all matter. A Renishaw is a turn-key calibrated instrument; this is a research-grade prototype.
Do I need an optical breadboard to build this?
Not strictly — aluminum extrusion can work — but rigid mechanical stability is not optional. Any vibration or thermal expansion in the optical path will swamp the measurement, so whatever you mount it to must be stiff and thermally stable.
Can I skip grinding the beam splitter and buy a commercial one?
Yes, and that is the sensible path if you want a working interferometer this decade. The hand-grinding is the impressive low-cost demonstration, not the recommended build route.
Is there firmware for reading out the fringes?
The repository includes KiCad electronics, which implies photodiode signal conditioning, but the README does not describe the full signal chain or published firmware. Check the commit history and video for clues.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
A $12 laser diode and hand-ground window glass, reaching nanometer resolution — if you had this running, what would you measure first?
Diffraction Limited (0x23)
Diffraction Limited is building open metrology tools that bring industrial-grade optical measurement within reach of hobbyists and research labs without $30,000 budgets. The nmWave interferometer is an active project, documented through build videos rather than polished guides.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM1d ago
Practical notes from verification: the repository is active and the video shows real optical alignment footage, but the CAD is explicitly marked Version 5 and work-in-progress, so expect iteration. There is no bill of materials as a single file — part callouts are in the README and video — and the KiCad sources ship as design files, not ready-made Gerbers, so you export those yourself. The single biggest surprise is that the beam splitter grinding is not a throwaway demo: the video shows it working, fringes and all, which makes the $12 diode claim credible. If you are already comfortable with optics and can tolerate an incomplete BOM, this is a weekend-plus project; if you need step-by-step instructions, it is not ready yet.