Uniformity of illumination
Homogeneity of the illumination surface, or better emitted surface (since UV-A radiation is not light), is the uniformity of the distribution of UV radiation.
Homogeneity is therefore so important, because UV-A radiation uses non-absorbable radiation and high-quality UV LED luminaires do not produce any visible reflections. As a result, the user may not notice when areas are not irradiated at all or too weakly. This ‘unvisible’ hazard can have a massive impact on the quality of an evaluation or bonding, even if the lamp system has been verified as sufficiently strong due to a classic UV intensity measurement (usually at a distance of 40cm).
This was already a topic with conventional incandescent lamp-based systems, but due to the use of usually only one incandescent lamp, it was negligible. If necessary, simple filters or reflection mirrors were used to scatter or focus the UV radiation. The inhomogeneities due to the design of the bulbs are far weaker than they can occur with UV LED systems and therefore almost uncritical for the user.
In LED technology, homogeneity is of particular importance, since, especially in the case of Floodlights, there may be a very high risk of partly far too low UV intensity (radiation holes) or a poor radiation distribution (inhomogeneities) which could not exist with the old technique in the strong form.
The great advantage of LED technology, however, is that almost any size of surfaces can be ‘illuminated’ in a previously unprecedented uniformity.
The homogenization of radiation at short distances when using as few UV LEDs as possible was one of the biggest technical challenges in the development of SECU-CHEK and also the optimization of Spectroline systems. In our UV emitters, the radiation is homogenized in such a way that the user has only a negligible fluctuation of intensity during the optical evaluation or irradiation of a certain surface, already from the specified distance.
SECU-CHEK supplies the UV LED lamps for standard applications such as the evaluation in fluorescent magnetic powder and penetration crack testing which guarantee an absolutely sufficient homogeneity from 12cm distance between the luminaire and the test surface, so that there is no risk of insufficiently fluorescent displays from this distance if a sufficient UV radiation strength of the system has been ensured by means of the classical intensity measurement.
For all luminaires, SECU-CHEK indicates the distance from which the user has adequate homogeneity and no longer there is a risk of insufficiently fluorescent displays or poorly cured areas within the illumination area.
Technically, we are able to build luminaires that provide a completely homogeneous illumination directly under the protective glass. However, this is not useful for UV intensities of less than 10,000 microns/cm2 (at 40cm distance), as they occur in NDT (Non-destructive testing).
Do you have any questions or are you unsure when choosing the right UV lamp?
Please do not hesitate to contact us!
We look forward to your inquiry!
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