Two UV spot curing system data sheets can quote numbers that look directly comparable and are not. Knowing where each figure was measured, and in what units, prevents a purchase that underperforms at the bond.

Q: Which Spec on a Spot Curing System Data Sheet Matters First?

A: Irradiance at Your Working Distance, Read Together With Wavelength and Spot Size

The headline irradiance on a spot curing system is usually its peak value, measured at the ideal focal point or at the lightguide tip. Your part sees the irradiance at the distance your fixture actually holds the guide. That figure, combined with the wavelength your adhesive needs and the spot diameter at that distance, decides whether a system will cure your bond. Every other number refines the choice. For a general introduction to the equipment, see Incure’s UV LED spot curing system guide; this article is about reading the numbers.

Peak Irradiance Versus Irradiance at Distance

Peak irradiance answers the question “how intense can this get?” Distance-specific irradiance answers “how intense will it be on my part?” Only the second predicts cure time.

Incure publishes a full falloff curve for the L9000™ rather than one number. Its peak of 7,500 mW/cm² at a 9 mm focal point drops to 223 mW/cm² at 30 mm, about 3% of peak. If a data sheet gives only a peak value, ask for readings at several distances, or plan to measure them yourself before committing to a fixture design.

Units and Measurement Points

Check the units before comparing two systems. Data sheets may quote irradiance in mW/cm² or in W/cm², and Incure’s own two spot platforms use one of each. The Incure S20™ arc spot lamp is rated at more than 21 W/cm² at the lightguide tip, which equals more than 21,000 mW/cm².

That does not mean the arc lamp delivers roughly three times the L9000™’s peak on a part. The two figures were measured at different reference points: one at the tip of the guide, the other at a 9 mm focal distance. A meaningful comparison requires both readings at the same distance from the same position, taken with the same radiometer.

Wavelength: Single Band or Broad Spectrum

A spec sheet lists either one wavelength or a range. The L9000™ is offered at 365, 375, 385, 395, or 405 nm, with each unit fixed at one wavelength from the factory. The S20™ emits a broad 275–650 nm spectrum from a mercury arc.

Read this line against the adhesive data sheet, not in isolation. A single-wavelength system is only useful if that wavelength falls within the adhesive’s absorption band. A broad-spectrum system covers more chemistries at once, but its intensity at the specific band your adhesive uses is a fraction of the total figure. Incure’s guide to the S20™ arc spot lamp’s lightguide configurations covers where broad-spectrum output fits.

Spot Diameter

Spot diameter tells you how much area receives the quoted intensity. On the L9000™, it ranges from 3 mm to 12 mm across its 9–30 mm focal range, growing as the guide moves back. A specification that lists only one spot size without a distance leaves out half the story, because spot size and irradiance change together.

Compare the spot at your working distance with the bond you need to cure. A bond wider than the spot will need multiple exposures or a flood source.

Email Us with the data sheets you are comparing, and Incure’s engineers can help line up the figures on a common basis.

Timer Range and Resolution

Timer specs look minor until exposure times get short. The L9000™ timer is programmable from 0.1 to 999.9 seconds, and the S20™ from 1 to 99 seconds. If your calculated exposure is under a few seconds, a finer timer step lets you set the dose closer to its target instead of rounding up by a full second.

Intensity adjustment is the companion spec. The L9000™ adjusts from 10% to 100%, and the S20™ from 25% to 100%. A wider range gives more room to tune dose without moving the fixture.

Life and Decay Ratings

Lifetime figures need a second number beside them: how much output is lost by the end. The L9000™ is rated for 15,000 hours with less than 20% intensity decay over that span. The S20™ mercury lamp is rated at 2,000-plus hours of lamp life, with replacement bulbs available for each configuration.

A life rating without a decay figure says how long a source runs, not how well. Ask what irradiance remains at end of life, then confirm that the residual output still delivers your dose at the working distance.

Integration and Readiness Specs

Several line items affect production more than cure quality:

• Control interface: the L9000™ supports PLC-triggered activation over RS-232.
• Warm-up: the L9000™ reaches full output instantly; the S20™ needs 1 to 2 minutes.
• Outputs per controller: up to four lightguides on the L9000™; one to four poles on the S20™.
• Power input: the S20™ is available for 100–120 VAC or 200–240 VAC, so order the version that matches your facility.

A Short Comparison Routine

When two systems are on the table, line them up in this order: wavelength match, irradiance at your distance, spot size at that distance, timer and intensity resolution, decay rating, then integration details. A system that fails the first two will not be rescued by the rest. Then verify the leading candidate with your own radiometer at the fixture, as Incure’s article on what a light guide does in a spot lamp system explains, since the guide itself shapes what reaches the part.

Final Thoughts

A spot curing system’s data sheet is accurate on its own terms, but those terms are not always your fixture’s. Translate every figure to your working distance, wavelength, and bond size before comparing. Contact Our Team to review a spot curing specification against your application.

Visit www.incurelab.com for more information.