A UV LED spot lamp purchase that looks straightforward at the quote stage often reveals hidden complexity during installation — a wavelength that doesn’t match the adhesive, an irradiance specification that doesn’t hold at production working distance, or a controller that lacks the features needed for process documentation. Asking the right questions before signing a purchase order prevents these discoveries from becoming production problems.
Questions About Wavelength and Spectral Output
What is the peak emission wavelength of the lamp? UV LED lamps are available at 365 nm, 385 nm, 395 nm, and 405 nm. Confirm the peak wavelength against the absorption spectrum of your adhesive or coating. A nominal “365 nm” lamp from different suppliers can have peaks ranging from 360 nm to 370 nm — the difference matters for some adhesive systems.
What is the spectral FWHM of the emission peak? UV LED emission is narrow — typically 10–25 nm FWHM. Confirm the actual spectral bandwidth, not just the peak wavelength. A photoinitiator with a narrow absorption peak may not respond to a lamp whose peak is at the edge of its absorption band, even if the nominal wavelengths sound compatible.
Can you provide the emission spectrum of the lamp? Request a plot of emission intensity versus wavelength. This confirms the peak wavelength and bandwidth from measured data, not just the nominal specification.
Questions About Irradiance and Working Distance
What is the irradiance at my working distance? Suppliers often specify peak irradiance at the lamp face or at a short reference distance (5–10 mm). Ask for irradiance data at your actual production working distance — the distance between the light guide tip and the adhesive surface in your fixture. If the supplier cannot provide irradiance data at your working distance, ask for the irradiance-versus-distance curve so you can interpolate.
How is irradiance measured? Ask whether irradiance values are measured with a calibrated radiometer traceable to a national standard, or derived from theoretical calculations. Measured values are more reliable. Confirm the measurement geometry matches your intended use (same light guide diameter, same spot size configuration).
Does irradiance remain stable over the cure cycle? For high-duty-cycle production curing, irradiance should be stable from the first second of exposure to the last. Ask whether the controller uses closed-loop irradiance feedback (maintaining constant output as the LED heats up) or open-loop power control (delivering constant power, with output varying as LED temperature changes). For process-critical applications, closed-loop regulation is preferable.
Questions About Spot Size and Coverage
What is the spot size at my working distance? Spot size increases with working distance as the beam diverges. Confirm that the spot covers your entire bond area within the irradiance threshold required for cure. Ask for spot size data at the working distance you intend to use, not at the lamp’s reference distance.
What irradiance threshold is used to define the spot size? Some suppliers define spot size at 1/e² (13.5% of peak irradiance), others at 50% or 80% of peak. Understand the definition and confirm that the threshold used is above your adhesive’s minimum required irradiance.
Is the spot shape circular, and how uniform is it? Ask for a beam profile — irradiance map across the spot — to confirm uniformity within the cure zone. Hotspots or irregular beam profiles produce uneven cure across the bond area.
If you need help evaluating whether a specific UV LED spot lamp will cover your bond area with adequate irradiance, Email Us and an Incure applications engineer will review the specifications with you.
Questions About Light Guides and Accessories
What light guide diameters are available, and what are the irradiance values for each? Light guide diameter affects spot size and irradiance. Larger diameter guides deliver larger spots with lower irradiance density; smaller guides deliver smaller spots with higher irradiance density. Confirm the available options and their irradiance characteristics.
What is the expected life of the light guide, and how is it replaced? Light guides degrade with use, particularly at the input end where UV intensity is highest. Ask for the expected replacement interval and the replacement cost. Confirm that light guides can be replaced in the field without returning the lamp to the factory.
Are right-angle or flexible light guide options available? Some bond joint geometries require angled or curved light guide delivery. Confirm whether the lamp system offers the delivery configurations your assembly requires.
Questions About Controller Features
Is exposure time programmable to sub-second resolution? Many UV adhesive cure cycles require 2–10 seconds of exposure. Timer resolution to 0.1 seconds is sufficient for most applications; sub-0.1 second resolution may be needed for fast-cure processes.
Can irradiance be adjusted? Programmable power level (as a percentage of rated output) allows you to tune irradiance to the adhesive requirement. If the lamp cannot be adjusted to deliver irradiance within the adhesive’s recommended range at your working distance, the lamp may not be suitable for the application.
Does the controller monitor output and alarm on deviation? Process control in regulated industries requires detection of lamp output degradation. A controller that monitors irradiance and alarms when output falls below a set threshold allows you to catch lamp aging before it causes cure failures.
Can process parameters be logged? For medical device, aerospace, or other regulated manufacturing, controller data logging of exposure parameters (time, power setting, accumulated dose) per production cycle provides the traceability record required for process validation.
What I/O options are available for automation integration? If the lamp will be integrated into an automated assembly system with PLC control, confirm the available digital I/O — trigger input, cure complete output, alarm output — and the communication protocol options.
Questions About LED Lifetime and Warranty
What is the rated LED lifetime? Ask for the L70 lifetime — hours to 70% of initial output — at rated operating conditions. This is the standard definition for LED lifetime. A lamp with 20,000-hour L70 lifetime will deliver at least 70% of its initial irradiance for 20,000 hours of operation at rated power.
Does the warranty cover the LED source or only the controller? Some suppliers warrant the controller separately from the LED module. Confirm what is covered and for how long.
Is irradiance maintained over the warranty period, or only lamp functionality? A lamp that functions electrically but delivers degraded irradiance is not meeting your process requirements. Ask whether the warranty covers irradiance output to specification, not just electrical operation.
Questions About Support
What technical support is available post-purchase? Confirm access to technical support by phone or email, response time commitments, and whether the supplier has application engineers who can help diagnose cure problems in your process.
Can the supplier provide IQ/OQ documentation for regulated manufacturing? If you operate under ISO 13485 or equivalent quality systems requiring equipment qualification, confirm whether the supplier provides the documentation package for installation and operational qualification.
Contact Our Team to speak with an Incure applications engineer about UV LED spot lamp selection for your specific curing application.
Visit www.incurelab.com for more information.