A Simple Photodiode Project for UV Photography and Video Safety
Low-cost UV monitoring to protect eyes, skin and sensors
UV photography is brilliant for science demonstrations, multispectral experiments, and creative imaging — but it brings one unavoidable challenge: UV safety.
Whether you’re photographing sunscreen patterns, checking fluorescence, or experimenting with a multispectral camera, you need to know how much UV light is present.
Commercial UV meters exist, but they can be costly and surprisingly limited.
So at Philip M Russell Ltd, we’ve built a simple Arduino-based UV photodiode monitor using inexpensive components. It gives fast, reliable readings and adds an important safety layer to our UV filming workflow.
Why Monitor UV at All?
UV is invisible — and that makes it dangerous.
Even relatively weak sources can cause:
-
discolouration of equipment
-
overexposed or bleached images
This matters in:
-
UV photography
-
multispectral camera tests
-
fluorescence experiments
-
mineral/forensic demonstrations
-
outdoor filming in strong sunlight
-
checking the safety of UV torches
-
studio work involving blacklight tubes
Having a little UV “traffic light” on the bench or tripod stand ensures you know when you’re operating safely.
The Core Components
The entire project can be built for under £15, using:
1. A UV photodiode
Common choices:
These respond to UV-A and/or UV-B depending on the model, giving a voltage proportional to UV intensity.
2. Arduino Nano or Uno
Perfect for reading analogue voltages, running simple code, and outputting values over USB or to a small OLED screen.
In order to get it work make sure to divide the output by the ADC of your MCU and multiply with the maximum voltage in mv. Example in Arduino: float sensorValue = analogRead(A0); float sensorVoltage = sensorValue / 1024 * 3.3; float UV_index_float = sensorVoltage / 0.1; int UV_index_rounded = round(UV_index_float);
3. A small display (optional)
An inexpensive 0.96" OLED lets you show:
-
raw millivolt reading
-
safe/unsafe warning
4. A diffuser cap
A small piece of white plastic or PTFE to even out incoming light and avoid directional bias in readings.
How It Works
-
The photodiode generates a small voltage when exposed to UV.
-
The amplifier module boosts this into a readable range.
-
The Arduino samples the voltage and converts it into a UV index or mW/cm² estimate.
-
A simple threshold triggers a visual or audible warning when UV rises above a safe limit.
Example thresholds:
-
Below 1.0 UVI – safe for long handling
-
1.0–3.0 UVI – brief exposure only
-
Above 3 UVI – eye protection required
-
Above 5 UVI – stop filming / increase shielding
Perfect for monitoring UV torches, LED strips, BLB tubes, and even sunlight through windows during photography.
Real Uses in Our Studio
We use our UV photodiode monitor to:
-
check UV lamps for intensity
-
verify UV leakage from multispectral setups
-
confirm when a scene is safe for close-up filming
-
protect camera sensors from long-term UV use
-
monitor UV output during sunscreen experiments
-
ensure students in online lessons can see the process safely
-
log UV levels as part of practical demonstrations
It’s particularly helpful when filming fluorescence experiments where the camera is close and multiple UV sources are involved.
Perfect Student Project
This is an excellent cross-curricular piece for GCSE or A-Level students:
-
electronics (sensors, ADCs, circuits)
-
physics (EM spectrum, photon energy, UV index)
-
computing (Arduino code, serial output)
-
biology (UV and skin safety)
-
media (safe filming workflows)
They can build, test, calibrate, and improve the device themselves — all using inexpensive parts.
The Takeaway
A simple photodiode UV monitor is a small project with big benefits.
It makes UV photography safer, protects equipment, and provides real data for science lessons and video production.
For a few pounds and an hour of assembly, you get a reliable tool that earns its place in every studio, lab, and classroom.
