ECO meters ship with a stick of fluorescent material with which you can check your meter's output response.
With the meter on and outputting data, hold the stick approximately 1/2-in (1 cm) from the lit detectors. Be careful to NOT touch the sensor face, as it scratches easily.
Pivot the stick to parallel with the meter's optics; the output in the meter's "signal" column should increase to near maximum output as given on the meter's characterization or calibration sheet. As you move the stick away, the output will decrease.
