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YOU CAN BUILD THE 15,000-DOLLAR LASER RIG THAT MEASURES FLOW, FOR 520 DOLLARS

A 520-dollar laser rig that measures fluid flow the way commercial systems do for 15,000 dollars.

by Frederick Kojo Chaway Acquah, Jeremiah Paul Konadu Takyi, and Heather R. Beem

FULL CAD BOM FIRMWARE DOCS

ScienceOpen-hardware

Built withArduino3D printing

difficulty
●●●●○
time
several weekends
license
CC-BY-4.0
repo
repo FINISHED0 stars

WHAT YOU’LL NEED

1
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COMPAREE VERDICT

This is a proper particle image velocimetry rig, built and validated by the engineering department at Ashesi University in Ghana for fluid dynamics research and teaching. PIV is the standard technique for measuring velocity fields in a flow — you seed the fluid with tracer particles, light a thin slice with a laser sheet, film it with a fast camera and correlate consecutive frames to map how fast every point is moving. The paper states that basic commercial systems run about 15,000 dollars, another system around 9,000 dollars, and in one published low-cost attempt the camera alone cost 3,000 dollars. This build came in at 520.50 dollars using a GoPro Hero 8 as the camera, a 300 mW 532 nm green laser module pulsed by an Arduino Nano through a small custom circuit, a cylindrical lens to form the sheet, and silver-coated hollow ceramic spheres (Conduct-O-Fil) as tracers, with PIVlab in MATLAB for the analysis. The team validated it on the rotating flow from a magnetic stirrer and measured velocities within 1-2% of the analytical prediction while the flow stayed two-dimensional, with repeatability within 6% between runs. The hardest part is optical alignment — getting the laser sheet thin, flat and perpendicular to the camera, then calibrating the pixel-to-millimetre scale. The paper walks through it, but expect to spend more time on setup than assembly. The second trap is the laser itself: the paper classes its 300 mW module as a Class 3 laser that can cause eye injury. Eye protection is not optional, and if your institution does not already have a laser safety protocol, you will need to write one before you power it on. If you are setting up fluid mechanics experiments and need to actually see what is happening in the flow rather than inferring it, this is the build. If you wanted a weekend project or have no use for quantitative flow measurement, it is not.

GOOD TO KNOW

  • —Full bill of materials with vendor links present in the HardwareX paper.
  • —Assembly instructions, optical alignment procedure and validation tests all documented.
  • —Design files (SolidWorks/STEP CAD for the extrusion frame, lens mount and enclosure, a DXF for the laser-cut control box, Arduino code and a KiCad schematic) are available at DOI 10.17632/cgmmttr4bz.2.
  • —Small custom firmware: an Arduino Nano pulses the laser using the published Laser_pulse.ino, with a KiCad schematic for the pulsing circuit; analysis runs in open-source PIVlab.
  • —Licence CC BY 4.0, permits commercial use.
  • —This is a functional 2D PIV system validated against analytically calculated velocities in a magnetic-stirrer flow, not a demonstration.

Parts to buy

5 items

From our check of the build. Exact quantities and part numbers are in the creator’s BOM.

  • GoPro Hero 8 camera and tripodFind
  • Conduct-O-Fil silver-coated hollow ceramic tracer spheresFind
  • Arduino Nano plus parts for the laser pulsing circuitFind
  • 2020 aluminium extrusionFind
  • Acrylic and plywood for the test sectionFind

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Can I build this?

PrintThe optical lens mount (supplied as a SolidWorks part in the Mendeley dataset; convert it to STL before printing). The control box is laser-cut from a DXF.
BuyGoPro Hero 8 camera and tripod, 300 mW 532 nm green laser module with a cylindrical lens, Conduct-O-Fil silver-coated hollow ceramic tracer spheres, Arduino Nano plus parts for the laser pulsing circuit, 2020 aluminium extrusion, acrylic and plywood for the test section.
Tools3D printer for the lens mount, access to a laser cutter for the control box, basic hand tools and soldering iron, laser safety goggles rated for 532 nm, MATLAB with the free PIVlab app, a ruler for the calibration image.
SkillsComfortable with optical alignment, reading a scientific paper for assembly steps, basic soldering of a small laser-pulsing circuit with an Arduino Nano, and running PIVlab in MATLAB. You also need to understand how to safely operate a Class 3 laser.
TimeOne weekend to assemble and mount components, another to align the optics and calibrate, then ongoing setup time per experiment. First useful flow measurement probably three weekends in.
Cost$$ — total bill 520.50 dollars as published. The GoPro camera is the largest single cost, followed by the laser module and optics. Tracer particles, electronics and frame parts are smaller but not trivial; 3D printing and laser cutting of the casing are not included.
SafetyClass 3 laser (300 mW, 532 nm) — direct beam or specular reflection can cause permanent eye injury in under a second. Laser safety goggles rated for the wavelength are mandatory for everyone in the room when the system is powered. If you are in an institution, coordinate with your safety office before ordering parts. Do not operate this in a space accessible to children or where someone could walk into the beam path without warning.

Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.

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Gallery

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Start here

Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.

  1. 1.Read the full HardwareX paper (DOI 10.1016/j.ohx.2024.e00563) — the bill of materials, assembly steps, alignment procedure and validation method are all there. (Open access, CC BY 4.0. This is the primary build document.)
  2. 2.Download the design files (CAD for the frame and lens mount, DXF for the laser-cut control box, Arduino code and circuit schematic) from the Mendeley dataset. (DOI 10.17632/cgmmttr4bz.2. The lens mount is a SolidWorks part that you convert to STL yourself (FreeCAD or Fusion 360 work as alternatives) before printing.)
  3. 3.Source the components from the bill of materials in the paper. The GoPro Hero 8 camera, the 300 mW green laser module and the Conduct-O-Fil tracer particles are the items to order first.(Vendor links are in Table 4 (BOM summary) of the paper. Prices were current as of publication (2024).)
  4. 4.Print the lens mount, build the laser control box and the 2020 aluminium-extrusion test-section frame, and set everything up as shown in the paper's Figures 1 and 8.(Assembly is straightforward — the hard part comes next.)
  5. 5.Follow the operation instructions in Section 6 of the paper: point the laser into the test section, mount the camera perpendicular to the light sheet, place the lens mount to form the sheet, and take a calibration image of a ruler so PIVlab can convert pixels to millimetres.(This is the step that takes time. The paper gives the procedure; expect iteration.)
  6. 6.Run a test flow (the paper's magnetic-stirrer vortex in a beaker is a good validation case), capture the video, and process it in PIVlab.(PIVlab is free and open-source but, as the paper notes, it runs inside MATLAB. The paper used it for all the validation work, and its author's tutorial playlist starts at https://youtu.be/g2hcTRAzBvY.)

KNOWN ISSUES

  • The camera is a GoPro Hero 8 — if you substitute another action camera, check that it records at least 1080p at 120 fps and lets you lock exposure, or your particle images will smear.
  • Getting a clean light sheet is not like assembling electronics: the cylindrical lens has to sit exactly in line with the beam, and the sheet has to land where the camera is focused, with the camera perpendicular to it. Budget time for this, and do not expect it to work on the first attempt.
  • The tracers are Conduct-O-Fil silver-coated hollow ceramic spheres (100 µm, density 1.0 g/cc), a fiberglass filler that is neutrally buoyant in water and much cheaper than purpose-made PIV particles. The paper notes their price is an estimate that depends on order size.
  • Laser safety is not negotiable. If you are in an institution, check whether you need a laser safety officer's sign-off before ordering a Class 3 source. If you are building this at home, understand that this is not a pointer — a 300 mW green beam can damage your retina faster than you can blink.
  • PIVlab is open-source and well-documented, but it is not a push-button tool. You will spend time tuning interrogation window size, overlap and validation thresholds to get clean vector fields. The paper gives starting parameters; expect to adjust them per your flow.
  • The 520-dollar figure is for the listed components. By the paper's own note it excludes 3D printing and laser cutting of the casing, and the tracer-particle price is an estimate. It also does not include whatever creates the flow you want to study (the validation used a magnetic stirrer), MATLAB for PIVlab, or the time cost of learning to set up the light sheet.

Can I use a different camera?

Yes, as long as it gives you enough resolution and frame rate for your flow. The paper used a GoPro Hero 8 at 1920 x 1080 and 120 frames per second, chosen because it beats the average smartphone on resolution and frame rate. A faster camera lets you measure faster flows; a slower one limits you to gentle flows like the magnetic-stirrer validation case.

What if I cannot source the exact laser module?

You need a visible green laser module (the paper uses a 300 mW 532 nm DPSS module with a TTL input) that you can form into a sheet with a cylindrical lens. The TTL input matters: the build pulses the laser from an Arduino Nano using the published Laser_pulse.ino code and pulsing circuit, so if you substitute a module, make sure it can be switched the same way.

How precise are the measurements?

The paper validated it on the rotating flow from a magnetic stirrer in a beaker: measured velocities were within 1-2% of the analytical prediction while the flow stayed two-dimensional, and the difference grew as the flow became three-dimensional. Repeatability between experiments was within 6%. Spatial resolution depends on your interrogation window size and particle density. This is a working lab instrument, but it will not match the performance of a commercial system.

Do I need MATLAB, or will Octave work?

The paper processed everything in PIVlab, which it describes as a MATLAB package that requires MATLAB to run. If you do not have MATLAB, the paper names OpenPIV, a mainly Python-based open-source tool with good documentation, as a reasonable alternative, but the published workflow and settings are for PIVlab.

Can I run this without an optical breadboard?

Yes — the paper itself does not use one. The rig is built on a 2020 aluminium-extrusion frame with the camera on a tripod. What matters is that the laser sheet and camera stay rigidly aligned between runs, so lock everything down once it is set and mark positions so you can return to them.

Is this only for water, or can I measure air flows?

The paper demonstrates it with water, but PIV works in any fluid you can seed. Air is harder because the tracer particles need to be small enough to follow the flow (smoke, oil droplets, or sub-micron solid particles), the density contrast is lower so you need more laser power or a more sensitive camera, and air flows are often faster so you need higher frame rates. Possible, but not trivial.

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Discussion1

FROM THE COMPAREE TEAM

The team built a working PIV rig around a GoPro Hero 8 and a 300 mW laser for about 520 dollars in parts, against commercial 2D systems the paper puts at roughly 9,000 to 15,000 dollars. Would a 120 fps action camera be enough for the flows you want to measure?

CompareeTEAM26d agoedited

Practical notes from our verification: the HardwareX paper is the build document: bill of materials with vendor links, assembly steps for the electronics, casing, optics mount and test section, and validation results are all there, open access. The design files are on Mendeley Data under DOI 10.17632/cgmmttr4bz.2, also CC BY 4.0: SolidWorks and STEP CAD for the 2020 aluminium-extrusion frame, plywood parts, lens mount and GoPro tripod base, a DXF for the laser-cut control box, the Arduino sketch that pulses the laser and a KiCad schematic of the pulsing circuit. The camera is a GoPro Hero 8 shooting 1920 x 1080 at 120 fps, the light source is a 300 mW 532 nm DPSS laser module pulsed by an Arduino Nano, and the tracers are 100 micron silver-coated hollow ceramic spheres. The paper calls the laser class 3 and says operators must wear laser safety goggles rated for 532 nm; ordinary glasses are not enough. Expect to spend time on getting a clean, thin light sheet and calibrating the pixel scale. Validation was done on the rotating flow of a magnetic stirrer in a beaker: measured velocities differed from the analytical prediction by 1 to 2 percent while the flow stayed two-dimensional, with repeatability within 6 percent. 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.

Frederick Kojo Chaway Acquah, Jeremiah Paul Konadu Takyi, and Heather R. Beem

Built at the Department of Engineering, Ashesi University in Berekuso, Ghana, with the stated goal of making PIV accessible to universities in the region. Published in HardwareX in 2024 as a fully documented, validated open-hardware instrument.

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