Use the same card, distance, phone position and room lighting every time. Consistency is what makes the comparison meaningful.
1 · Which light?
Add a light to begin. Each light keeps its own baseline and history.
2 · Aim the camera
Point the rear camera at a white matte card.
Fix the phone (a stand or box works), hold the light tip against the card inside the ring. Never look into the beam.
Signal
--
Light: --
Exposure: --
Camera lock: --
3 · Capture
Tap the button, switch the light on when told, then off when told. Lumos takes three readings, uses the middle one and subtracts room light.
Start the camera and pick a light first.
Result
No reading yet
Set a baseline with the light when it's known to be good (new, serviced, or radiometer-checked). Then run checks against it.
ServiceWatchPass
Output vs baseline--
Est. irradiance--
Repeatability--
Reading quality--
Exposure time guide
At about -- mW/cm², a 2 mm increment needs roughly -- s to receive ~16 J/cm². Always follow the composite's IFU when it asks for more.
What to do next
My lights
Data stays on this device. Use Backup to move it to another phone.
Why check curing lights at all?
Surveys of dental clinics keep finding lights with far less output than their owners assume. Common causes are resin on the tip, cracked or chipped light guides, ageing batteries and failing LEDs. An undercured restoration looks the same on the day it's placed. Over time it brings more wear, staining, secondary caries, debonding and monomer elution.
Irradiance vs energy (radiant exposure)
Irradiance (mW/cm²) is how intense the light is. Radiant exposure (J/cm²) is irradiance × time, and it's what the resin actually receives. A widely quoted target is about 16 J/cm² for a 2 mm increment of a typical shade. That's around 16 s at 1,000 mW/cm², or 20 s at 800. Darker shades, opaque materials and bulk-fill composites may need more, so check the IFU.
Energy delivered20 J/cm²
Distance matters more than you think
Irradiance falls off quickly as the tip moves away from the resin. At the floor of a deep Class II box (often 6–8 mm away), many lights deliver only half of what they give at the tip, or less. Diverging beams fall off fastest. Keep the tip close, parallel to the surface and centred over the restoration. In deep boxes, add time instead of trusting the setting.
Monowave vs polywave
Camphorquinone (CQ), the most common photoinitiator, absorbs blue light at around 470 nm. Some materials also use TPO or Ivocerin, which need violet light below 420 nm. A blue-only (monowave) light can undercure those materials, so match the light to the material. Lumos screens the blue band best. Its violet sensitivity depends on your phone camera.
Daily care that keeps output high
- Look at the tip every day. Remove cured resin with a plastic instrument, not a metal scraper.
- Use clear, well-fitted barrier sleeves. A creased or doubled sleeve cuts output.
- Replace light guides that are cracked, chipped or cloudy.
- Follow the manufacturer's battery care. Output can sag as the charge runs down.
- Let lights cool between long exposures. Some throttle when hot.
How to get trustworthy Lumos readings
- Fix the phone in a stand. Keep it at the same height every time, about 10–15 cm above the card.
- Use the same white matte card, and put a mark where the tip goes.
- Use the same room lighting each time, and keep direct sunlight out.
- Set the baseline when the light is known to be good: new, just serviced, or checked on a radiometer. Enter that radiometer value if you have it.
- Check weekly or monthly, and always after a drop, repair or tip change.
- If the result says Watch or Service, clean the tip, charge the battery and run the check again before deciding.
What Lumos can and can't do
A phone camera isn't a radiometer. It can't measure absolute irradiance or spectrum, and auto-exposure can mask small changes. What Lumos does reliably is flag a relative drop against that light's own baseline under the same setup. Treat the irradiance figure as an estimate scaled from your baseline value. Use a calibrated radiometer or spectrometer for formal documentation and regulatory decisions.
Further reading
- Price RB, Ferracane JL, Shortall AC. Light-curing units: a review of what we need to know. J Dent Res 2015;94(9):1179–86.
- Shortall AC, Price RB, MacKenzie L, Burke FJT. Guidelines for the selection, use, and maintenance of LED light-curing units – Part 1. Br Dent J 2016;221:453–60.
- Rueggeberg FA, Giannini M, Arrais CAG, Price RBT. Light curing in dentistry and clinical implications: a literature review. Braz Oral Res 2017;31(suppl 1):e61.
- ISO 10650:2018 Dentistry — Powered polymerization activators.