With the release of Microscan’s new NERLITE Smart Series machine vision lighting, which boasts brighter LED lighting compared to their predecessors, I have encountered several questions in regard to choosing LED lights, as well as common obstacles and frustrations. I wanted to share my thoughts on a few of the recurring questions to help make the selection of your next LED light a little easier.

Temperature and LED longevity. Is a hot LED light a bad LED light?

While it is a fact that the cooler a particular LED is the longer it will last, this is much too broad of a generalization. Different LEDs have a very wide range of maximum operating temperatures. Using a “hot to the touch” test, some LEDs may appear to already be past their limits while others might not be even close. This test used to be a good rule of thumb in the early days of LED illumination, but devices have significantly evolved and heat does not always mean a bad design. For example, Microscan’s new NERLITE Smart Series DOAL lights run hotter than our previous design and are warmer to the touch, but the LEDs are robust enough that we were able to increase intensity, improve uniformity, eliminate cooling fins, and operate the unit at a 10 degree Celsius greater maximum ambient temperature than previous standard DOALs. Thermal management is always one of the key factors in our designs and we test our prototypes to verify safe operating temperatures for the internal components. It's noteworthy to mention, also, that the overall life of the product was not compromised in comparison to its cooler-running predecessor.

Mechanical assembly. Is the light’s assembly rigid? Does it have good mounting points? Will it endure years of vibration? Can it be cleaned easily?

These are excellent considerations when choosing an LED light for your application, especially if you are working in a rugged environment or extreme conditions. With Microscan’s Smart Series product line, we were able to take into consideration feedback from application engineers and customers to incorporate more common mounting points while maintaining backward mounting compatibility to prior product. Each design was subjected to shock and vibration testing to ensure mechanical stability in the field and we also took into consideration IP ratings that are common to each product family. Our latest NERLITE Smart Series HI-BRITE lights were designed to be IP64 due to the likelihood of being used in a washdown environment. In terms of cleaning, it is important to note all units with beam splitters, regardless of manufacturer, have special cleaning requirements. This is due to the delicate nature of the coatings used on the beam splitters.

LED placement. How uniform is the pitch? The height? Are any LEDs pointing off-axis?

If the LEDs in a given light are not positioned uniformly, the output will not be uniform either. With non-diffuse, focused LED arrays, the trueness of LED placement makes a big difference and dictates uniformity of light coverage. For example, when NERLITE products require specific LED alignment, we either incorporate the alignment feature into the design or specifically design alignment tools to be used at the time of assembly.

LED light uniformity. Which produces more uniform light: a high concentration of smaller LEDs or a low concentration of large LEDs?

For non-diffuse, short working distance area arrays and ring lights, it is basically true that hot spots can be reduced by a higher concentration of smaller LEDs. However, this does not take into account the output angle of the LEDs’ optics. Even packed tightly together, an LED with a very narrow output angle can still be spotty. LEDs with a wide output pattern can be more uniform even if they are more spread out. So, the high concentration/small LED rule is useful when considering the uniformity of non-diffuse, focused LED arrays, but when it comes down to having a truly diffuse light source, seeing "any" type of LED is not a good sign. Microscan NERLITE has applied many techniques, often patent protected, to achieve superior uniformity regardless of LED size or quantity. A great example of this is the NERLITE Backlight family. The Large Area Backlight technique utilizes a smaller number of large LED's to achieve uniformity, while the Edge to Edge Backlight technique utilizes a larger number of small LED's to achieve the same. One final note is that for area array lights designed for long working distances (such as our Smart Series HI-BRITE lights), the overlap that occurs over the long distance makes LED density less of an issue.


True value. Can the cost of wattage consumption provide accurate value of a light?

There is a common assumption that power consumption correlates with light output. This means, hypothetically speaking, one could work out the value of a particular light by calculating the price per watt that the light uses. On the surface, such a calculation might show that the differential between the cheap and the expensive light is not as great as it appears at first.

This may be true when comparing "apples to apples," but Machine Vision Illumination has entered a new era in which more technical features are designed into the product itself. This simplistic approach to calculating light value based on watts consumed does not take into account the quality and integrity of construction, IP rating, optical design, efficiency of the electronics and optics, ease of use (mounting options, accessories, etc.), warranty, and so on. Even if all other factors are equal, some LEDs are more efficient than others. For example, Microscan’s new NERLITE Smart Series Ring lights use about the same amount of power as their predecessors (standard Ring lights), yet they contain 25-33% more LEDs and have 3-5X the light output depending on the model. Since the price and power consumption is about the same, by these criteria, one would judge the old and new units to be equal in value. This is, of course, totally false. Whether it's just simple circuit protection or the comprehensive control features built into Smart Series Illuminators, there are vast differences in these lights’ capabilities. The moral is: Sometimes you truly do get what you pay for.

Learn more about NERLITE machine vision lighting on our website. If you have any questions, feel free to contact us!