Are We Measuring Light the Right Way in tPBM?

Transcranial photobiomodulation (tPBM) is still a relatively young field, and with that comes a lot of unknowns, especially when it comes to accurately measuring the light output of these devices. One of the biggest challenges we’ve encountered (and we’re not alone) is the lack of clear, industry-wide guidelines or standardized testing procedures.

At Neuronic, we’re not just engineering and measuring our own tPBM devices. We're also committed to leading the way in creating more transparency and setting new standards in how the field reports and understands light measurements.

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Why Measuring Light Isn’t So Straightforward

Let’s take a look at measuring irradiance, a common problem in the PBM field.

It’s surprisingly easy to end up with conflicting or confusing results, even when you’re working with the same device or same LED just because the measurement method wasn’t clearly explained or standardized in the first place.

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Let’s break it down to illustrate the point:

If you measure a 100 mW LED using a 1 cm² diffuser, and all the light hits the diffuser, you’ll get an irradiance reading of 100 mW/cm².

But if you measure a 100 mW LED capturing all emitted light by using a 0.25 cm² diffuser, you’ll get a much higher irradiance measurement of 400 mW/cm².

It’s the same device, same LED, but very different results.

That’s why we at Neuronic believe it’s so important to consider both irradiance and total power when measuring PBM devices. Looking at just one metric doesn’t paint the full picture.

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The following picture shows how drastically irradiance values and total power outputs can vary:

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What We Measured and Why It Matters

To explore this critical issue in measuring and reporting, we conducted an internal study focused on quantifying total power, irradiance, and peak wavelength of two of our devices:

• Neuradiant 1070
• Neuronic LIGHT

We used multiple spectrometers and power meters, tested different measurement setups (including various diffusers and filters), and recorded over 2,000 individual measurements.

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Here’s what we found:‍

Our takeaway? Measurement results can vary widely depending on the tools, techniques, and assumptions used. That’s why laying the groundwork for accurate, transparent reporting is essential for moving the PBM industry forward.

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Want to Learn More About Measuring Light?

We just hosted a Discussion Round where our team broke it all down. We went over what we measured, how we did it, and why it matters for the future of PBM dosimetry.

Watch the full recording and see how we approached the challenges of measuring whole-head tPBM devices.

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Fill out the form below to have our preliminary results paper sent directly to your inbox and explore the data in more detail.