SFLINT luminance photometers
The lighting requirements of a tunnel depend on the human eye. Its level must be adjusted so that users, irrespective of natural lighting conditions, day or night, can approach safely and are able to detect possible obstacles.
The SFLINT luminance meter makes it possible to measure the luminance at the tunnel portal in order to ensure that the driver can adapt to the lighting conditions inside the tunnel. The device takes the measurement in a 20° cone (according to CIE 88:2004 recommendations) and gives the measurement in a range that can be adjusted to the user’s needs (typically 0 – 60000 cd/m² in the model with digital output, while in the analogue model the upper limit usually ranges between 5000 and 20000 cd/m²).
The system uses a silicon photodiode with spectral response matched to that of the human eye and has an internal heating system to prevent fogging.
As indicated above, there are two models depending on the output:
SFLINT-485, with digital output on RS485 bus, and SFLINT-c, with analogue output on 4-20 mA current loop. Both are available in versions adapted for use inside the tunnel, with a reduced measurement range of up to 500 cd/m².
The entire system is supplied in an anodised aluminium housing, adjustable in elevation and azimuth, which can be fixed to a wall or pole.