When a spot-cure process starts producing soft bonds, the question is whether the lamp has aged or the light guide has clouded. A lightguide simulator answers it by letting a radiometer read the lamp's true output with the guide taken out of the equation. The Measurement Problem It Solves In a spot curing system, energy passes from the lamp through a fiber or liquid light guide to the work. Both the lamp and the guide lose transmission over time. If you only measure irradiance at the guide tip, a low reading could come from either one, and you cannot tell whether to change a bulb or replace a guide. Measuring at the lamp's output port directly is also unreliable, because the coupling optics and acceptance angle differ from what the guide actually sees. How a Lightguide Simulator Works A lightguide simulator is a short optical component that presents the same input aperture, acceptance angle, and connector as a real light guide, but with a stable, known transmission and no meaningful aging. You connect it to the lamp in place of the production guide and read the output with your radiometer. Because the simulator's transmission is fixed, any change in the reading over weeks or months reflects the lamp, not the delivery path. Swapping the production guide back in and comparing readings then isolates how much loss the guide has added. What You Learn From It Lamp degradation trend: a declining simulator reading over service hours shows the bulb or LED module is losing output before cure quality drifts out of spec. Guide condition: the gap between the simulator reading and the in-line guide reading is the guide's transmission loss; when that gap grows past your limit, replace the guide. Baseline for new equipment: record the simulator reading when a system is commissioned so later checks have a reference. Process validation data: documented output checks support quality records for regulated production. Email Us to discuss adding a simulator check to your preventive maintenance routine. Using It Correctly Match the connector and diameter to your system, typically a 5 mm or 8 mm guide interface. Match the wavelength band of your radiometer detector to the lamp, whether a broadband arc source or a single-wavelength LED. Fix the measurement geometry: same distance, same aperture, same warm-up time on every check, since arc lamps need several minutes to stabilize. Log every reading with date and lamp hours so the trend, not a single number, drives decisions. Send the radiometer for calibration on the manufacturer's interval, usually annually, so a drifting detector is not mistaken for a drifting lamp. A simulator complements routine radiometry and scheduled guide inspection rather than replacing them. For background on why guides lose transmission, see what causes UV light guide degradation over time, and for how the delivery component works, what a light guide is in a UV spot lamp system. Building the Verification Routine A workable schedule looks like this. At commissioning, warm the lamp fully, connect the simulator,…