LASERTWEEZER: AN OPEN-SOURCE OPTICAL TRAP BUILT FROM A DVD PICKUP
Grab and move microscopic beads with a beam of light using a salvaged DVD burner pickup, a webcam and an Arduino.
by Urs Gaudenz
ScienceOpen-hardware
Built withArduino
- difficulty
- ●●●●○
- time
- a weekend-plus
- license
- license not specified
- repo
- repo FINISHED0 stars
●●●●○ · a weekend-plus · license not specified · 0 stars · repo FINISHED
WHAT YOU’LL NEED
Jump to section
COMPAREE VERDICT
This is a Nobel-winning physics technique stripped down to consumer electronics: an optical pickup from a DVD drive becomes the laser trap, a USB webcam with its lens reversed becomes the microscope, and an Arduino drives both plus a motorised shutter disc so the camera sees the trapped bead instead of laser glare. About 40 mW reaches the trap, magnification is roughly 400×, the whole instrument weighs under 500 g and parts cost under 100 dollars. The schematics, board layout and control firmware are published, and a demonstration video shows polystyrene beads being trapped and moved. The documentation is excellent for someone who already understands optics and electronics — there are theory explanations, a construction description, circuit diagrams, and a clear video — but this is not a paint-by-numbers build. You are expected to fabricate the frame, align the optics by eye, and debug the focus and trap yourself. The single biggest trap is buying the wrong DVD drive: not all pickups have the same focus range or laser power, and there is no compatibility list. If you have built open-hardware lab equipment before, or if you are comfortable with optical alignment and are willing to iterate, this is a weekend of deeply satisfying work. If you are new to either optics or embedded electronics, expect a weekend-plus and be ready to ask for help. The payoff is a working instrument that does something genuinely hard for less than the cost of a textbook.
IN THE REPO
GOOD TO KNOW
- —Schematics, PCB layout (Eagle format) and Arduino control code are published on the project page.
- —No 3D models or mechanical drawings — you build the frame yourself or follow the photos.
- —The documentation is a detailed project page with photos, video and theory, not a step-by-step assembly manual.
- —The design follows the published academic method by Kasukurti et al., 'Single-cell isolation using a DVD optical pickup'.
- —No stated licence and no open-source licence file; ask the author before reusing the files commercially.
Parts to buy
10 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Videos
DIY Open-Laser-Tweezer based on a WebCam and a DVD Laser
No official video walkthrough — the project page embeds a demonstration video showing beads being trapped, but there is no build tutorial.
More builds like this
All projectsGallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the project page and watch the demonstration video to understand what the instrument does and how it works. (The page is dense but thorough — read the theory section and the parts list before ordering anything.)
- 2.Source a DVD drive optical pickup — this is the core of the build and the part most likely to vary.(Not all pickups work equally well; expect to try more than one. The project page does not provide a compatibility list.)
- 3.Download the Eagle schematics and board layout, then either fabricate the PCB yourself or send the files to a PCB service. (The free version of Eagle can open the files. If you are new to PCB fabrication, budget time to learn the export process for Gerbers.)
- 4.Assemble the electronics, upload the Arduino code, and test the laser and shutter disc before attempting optical alignment.(Get the motorised shutter working first — it is easier to debug when you can see what the camera sees without the laser blinding it.)
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 DVD drive optical pickup is not a standard part — not all drives have the same laser power, wavelength or focus range, and there is no published compatibility list. Expect to source more than one and test them.
- There are no mechanical drawings or 3D models for the frame. You fabricate it yourself from the photos, or improvise. If you are not comfortable with freehand mechanical assembly, this will take longer than the electronics.
- Optical alignment is done by eye and iteration. The project page explains the theory but does not provide a calibration procedure. If you have never aligned a laser or a microscope before, budget time to learn.
- The PCB layout is provided in Eagle format. If you have never exported Gerbers or ordered a board before, that step alone can take half a day the first time.
- The Arduino control software is published with the board files, but the page does not explain it; to change shutter timing or the pilot-laser dimming you will need to read the code yourself.
- The 40 mW laser output is a Class 3B eye hazard. If you are not familiar with laser safety or do not have appropriate goggles, do not proceed — the risk is permanent eye damage.
Can I use any DVD drive?
No — you need the optical pickup from a DVD burner (writer), whose red laser diode is powerful enough; the method paper used a 20x DVD burner sled with a 660 nm, roughly 200 mW diode. Pickups vary, the project page gives no compatibility list, so expect to source more than one and test them.
Do I need to fabricate a PCB, or can I breadboard this?
The schematics and board layout are provided, and the design assumes a PCB for mechanical stability and clean signal routing. You could breadboard the electronics for initial testing, but the final instrument needs the board — optical alignment is hard enough without mechanical flex.
Is there a step-by-step build guide?
No — the project page is detailed and includes theory, a construction description naming the main parts, downloadable schematics, board layout and Arduino code, and a demonstration video, but no parts list with part numbers and no step-by-step assembly manual. It is written for someone who can read a schematic and improvise the mechanical assembly from photos.
What can I actually trap with this?
The GaudiLabs demonstration video shows small polystyrene beads being trapped and moved. The academic paper the design is based on used a DVD burner pickup to trap micron-sized colloids and red blood cells. Trapping cells needs clean sample preparation and is harder than beads, and the DIY build has only been shown with beads.
Is this safe to use at home?
Only if you are experienced with laser safety. The beam is about 40 mW of red light from a DVD burner diode (around 660 nm in the method paper), which is in the Class 3B range and an eye hazard. Wear goggles rated for the red wavelength of your diode, keep the beam path enclosed and controlled, and never look into the optics. If you are not familiar with laser safety protocols, this is not a beginner project.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
The schematics, board layout and Arduino code are all published, but the project page does not specify which DVD drive models work best — and not all optical pickups have the same laser power or focus range. If you have built this or tried different drives, which one did you use and how did it perform?
Urs Gaudenz
Urs Gaudenz is the founder of GaudiLabs and a core contributor to Hackteria, an open science network that develops DIY lab equipment and art-science installations. The LaserTweezer was built as part of Hackteria's mission to make scientific instruments accessible outside traditional research institutions, and the design follows an academic method published by Kasukurti et al.
Keep building — related projects
Same category or platform, picked by how close they are to this build.
FULL CADYou can 3D print a lab centrifuge that runs on a 12V motor and a switch
ScienceFor intermediate builders
FULL CADYou can build the 10,000-dollar lab shaker for 169 dollars
ScienceFor intermediate builders
FULL CADLabs pay 18,000 dollars for a 96-channel pipette. He built one for 250 dollars
ScienceFor advanced builders
FULL CADYou can build the 4,750-dollar machine that makes rapid test strips, for 200 dollars
ScienceFor advanced builders
FULL CADYou can build the 15,000-dollar laser rig that measures flow, for 520 dollars
ScienceFor advanced builders
FULL CADA seabed sonar that logs on its own for months — the logger, housing and batteries cost 1,700 EUR
ScienceFor expert builders
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.
CompareeTEAM1mo agoedited
Practical notes from our verification: the project page is hosted on gaudi.ch and includes a demo video, the theory, a construction description that names the main parts, and a downloadable package with the Eagle schematic and board layout plus the Arduino sketch. There is no GitHub repository, no licence statement, no CAD for the mechanical frame and no formal parts list with part numbers, so you work from the description and photos. The most concrete trap is the optical pickup: it has to come from a DVD burner, the page does not list compatible drives, and laser power and focus range vary between models. The 40 mW beam and the under-100-dollar cost are the creator's published numbers, but we have no independent test data. Take laser safety seriously: the red beam in the tens of milliwatts is in the Class 3B range and can cause permanent eye damage, so use goggles rated for the red wavelength. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.