Display of the spectral BLH adaptation of a typical LMK
LMK Blue Light Hazard
The EN 62471 standard deals with the photobiological safety of lamps and lighting systems. It specifies limit values for various effects on the eye. Among others, the blue light hazard (BLH) of the human eye. Compliance with these limits and threshold values can be monitored by measurements.
The measurements with the LMK are based on the determination of the weighted radiance Le(BLH) (λ) by spectral filtering with a full-glass filter.
Depending on the standardized sorting into risk groups, certain measurement angles or aperture angles must be used: 100 mrad (5.73 °); 11 mrad (0.63 °) or 1.7 mrad (approx. 0.1 °).
To measure the blue light hazard (BLH), the filter wheel of the LMK color must be equipped with a filter glass that is adapted to the sensitivity function for the blue light hazard. The measurement result when using the BLH filter glass is calibrated to the absolute radiation [W / sr * m²] weighted with BLH. If you use this filter glass to take a measurement image, the information provided in the measurement image is linked to the BLH weighted radiance Le (BLH) (λ).
BLH filtered/weighted image with 100mrad (left), 11mrad (middle) and 1.7mrad (right) aperture combined with the display (blue colored) of the 50% emission threshold to determine the size of the active angular area α in mrad.