ILLIOS Tunnel Illuminance Photometer to ensure interior illumination levels

Designed specifically for the tunnel environment, the ILLIOS measures the level of illuminance within the tunnel bore to ensure interior illumination levels are being continuously maintained in order to ensure safe lighting conditions for drivers. Illuminance, or incident lighting, determines the amount of light that covers a specific surface or area within the tunnel.

The ILLIOS uses a specially designed, highly light-sensitive photocell to continuously measure cosine corrected planar illuminance within the tunnel thus allowing elimination of directional error. The measurements are converted into an output signal of 4-20 mA (directly proportional to the illuminance measurement) for hard wire connection and signal transmission to a host controller.


  • Accurate measurement of illuminance within the tunnel bore
  • CIE Approved measurement technology
  • Silicon photo diode, Vλ filtered to provide a spectral response close to that of the average human eye
  • IP65 / NEMA 4X rated external enclosure
  • Operating temp of -30°C to +70°C ensures stable readings across all prevailing ambient temperature conditions
  • Supplied complete with PC based utility software for set-up and control of the instrument


  • Designed specifically for monitoring in tunnels
  • Rugged design to withstand corrosive atmosphere and regular tunnel washing
  • Simple installation and mounting
  • No moving parts and low maintenance requirements
  • Flexible integration options

Support Documentation

ILLIOS Tunnel Illuminance Photometer

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