ISO/TR 20772 & ANSI Z80.33 Standards: Blue Light Hazard Spectral Metrology

Under ISO/TR 20772 and ISO 8980-3, the official Blue Light Hazard Transmittance ($\tau_B$) cannot be measured with a simple laser pointer; it requires integrating continuous spectral transmittance across an integrating-sphere spectrophotometer:

$$\tau_B = \frac{\int_{380\ \text{nm}}^{500\ \text{nm}} \tau(\lambda) \cdot E_{S}(\lambda) \cdot B(\lambda) \, d\lambda}{\int_{380\ \text{nm}}^{500\ \text{nm}} E_{S}(\lambda) \cdot B(\lambda) \, d\lambda}$$

Where:

• $\tau(\lambda)$ is the measured spectral transmittance of the spectacle lens blank.
• $E_S(\lambda)$ is the standard solar or CIE LED test illuminant spectral irradiance.
• $B(\lambda)$ is the ICNIRP Blue Light Hazard Weighting Function.

The international standard establishes two critical sub-bands:

1. Blue-Violet Band (380 nm to 455 nm): The hazardous phototoxic and scatter spectrum. Lenses should exhibit significant attenuation ($au_B < 40\text{--}60\%$ in this band).
2. Blue-Turquoise Band (465 nm to 495 nm): The non-visual circadian band required for daytime alertness and pupillary reflexes. Lenses must maintain high transmittance ($> 80\%$) to preserve normal color vision.

A critical legal requirement under ISO 14889 for driving safety is the Relative Visual Attenuation Quotient ($Q$-factor) for traffic lights (Red, Yellow, Green):

$$Q_{\text{signal}} = \frac{\tau_{\text{signal}}}{\tau_v} \ge 0.80$$

Cheap, uncertified yellow lenses frequently fail the green traffic light test ($Q_{\text{green}} < 0.80$), turning green signals into confusing gray dots. ELLASUV BluePro Lenses meet 100% ANSI Z80.33 and ISO 14889 standards, ensuring total optical safety and crystal-clear color fidelity.