Tunnel Illuminance Photometer

The ILLIOS measures illuminance inside the tunnel bore to help maintain safe lighting conditions for drivers.


Accurate measurement of illuminance within the tunnel bore
Silicon photo diode
Silicon photo diode, Vλ filtered to provide a spectral response close to that of the average human eye
Rugged design
Rugged design to withstand corrosive atmospheres and regular tunnel washing
Rated external enclosure
IP65 / NEMA 4X rated external enclosure
Self contained intelligent analyser
Self contained intelligent analyser for direct connection to host controller

See our technology in action.

Schedule a free demo to get a first-hand look at how our solutions support your business.


Illuminance or incident lighting determines the amount of light that covers a specific surface or area within a tunnel. The ILLIOS measures the level of illuminance within the tunnel bore to help ensure interior illumination levels are continuously maintained in order to provide safe lighting condition for drivers.

The ILLIOS has a stainless steel, IP67 rated case that has been designed specifically for harsh tunnel environments. The ILLIOS measures the illuminance over a standard range of 0-20,000 Lux, which can be scaled to meet the user’s environment. The ILLIOS is a self-contained intelligent analyser, measurements are available via RS485 (Modbus RTU), Current Outputs and Digital Relays.


  • Designed specifically for monitoring in tunnels
  • Simple installation and mounting
  • No moving parts and low maintenance requirements
  • Flexible integration options
  • Supplied complete with PC based utility software for set-up and control of the instrument


Use ILLIOS in large temperature range

The ILLIOS has an operating temperature range from -30º C to +70ºC which ensures stable readings across all prevailing ambient temperature conditions.

Request pricing

Connect with Acoem

Contact us to learn more about our solutions, services, and training programs.

Would you like to…?