[solarmeter®]

Todd,

Biological responses to ANY bandwidth of light (UV, visible, IR) is proportional to dose. Dose is the product of intensity and time. The meter measures red light intensity centered about 633nm. It's as simple as that... period.

In other words.... intensity (dose rate) and dose have a reciprocal relationship (law of reciprocity). Pure physics. No doubt about it.

OK. Now what does a Red LED meter reading "mean". What does the above 116.8 mW/cm² mean compared to a Lumiere at say 85.0 or an Omnilux at say 105.0? Simple (1.) and not so simple (2) below:

1. IF all three had the exact same SPD (spectral power distribution) - then there is a proportional efficacy relationship adjusted for session minutes/seconds (assuming they all emit similar IR ~830nm too).

2. IF all three have different peak irradiance (say 629nm, 633nm, 640nm) and/or different wavelength bandwidth at bottom of LED bell-curve.... then one needs to convolute specific nm intensities by the meter's response and integrate the result.

Both of the above assume that all 3 units have narrowband LED irradiance falling within the "CAS" (collegen action spectrum) covered by the meter's spectral response. Don Smith has a copy of the CAS if you don't already have it.

Same is true for Ery (Eeff) UVR intensity based on the EAS (erythemal action spectrum) long ago validated by Model 7.0 readings vs FDA, and recently by Model 7.5 readings in accordance with the Euro-Norm 0.30 W/m² dose rate cap.

So put all that mumbo-jumbo in your pipe and smoke it for a while. This is the No-Spin-Zone when it comes to science based meter readings. Otherwise the original poster (S. Underhill) would have re-posted by now lol.