UV-A and Visible Light Intensity
In accordance with ASTM E1444/E1444M, Black Light or UV Lamps must produce a minimum acceptable intensity of 1000 μW/cm2 at 15 inch [38.1 cm] from the front of the filter to the face of the sensor. If the UV light produces more than the accepted ambient visible light, then it causes risk of missing critical indications. Ambient visible light produced by the Lamp during Fluorescent magnetic particle examinations in a darkened area can have a maximum ambient light level of 2 fc [22 lx] measured at the part surface.
Both the UV and Visible intensity shall be checked with meters that are to be calibrated every 6 Months by the manufacturer or by any Nationally accredited laboratory.
Beam Irradiance Profile Emitted by the Lamp
The UV Lamp must emit a uniform beam with the beam irradiance profile in accordance with ASTM E3022 from a distance of 15 ± 0.25 inch [38.1 cm] above the surface of a flat, level workbench with the projected beam orthogonal to the workbench surface. This is to ensure that a in a given area, the UV Light is rationally distributed so as to avoid any chance of missing critical surface defects.