The success of any test involving fluorescence (LPI, MPI, contamination, etc.) is based on having sufficiently high UV intensity vs. sufficiently low Visible light intensity for optimum contrast. All relevant NDT Codes stipulate these values. It should be noted that legacy Mercury lamps decrease in intensity with age, use and contamination, with significant decreases in intensity occuring unpredictably.
We offer Radiometers (UV Meters) and Photometers (Visible Light) meters from Spectronics, UV Products, Magnaflux and our economy - house brand.