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Shining the right light
How the optics you choose can make or break your lighting project


In earlier articles we've covered the most important considerations lighting professionals need to take into account when designing lighting for use in applications like roads and tunnels. Now we turn to a narrower question, one that has to do with the distribution, amount, and quality of the illumination emerging from a light source. More specifically, how can the choice of optics make or break a lighting project, and how can lighting pros ensure they’re taking all relevant criteria into account when selecting optics?

Different applications require different optics, as professionals are increasingly coming to understand. Yet many manufacturers still rely on off-the-shelf optics. Why? Because they're used to it. That's the way they got accustomed to building luminaires in the pre-LED past, when complete standardization was the industry watchword.

 

But with the introduction of the small LED light source, the situation changed. Small LED sources could deliver sharper light distributions, thus cutting down on spill light – and, significantly, increasing energy savings. A rigidly standardized optic, on the other hand, prevents full optimization of light quality and degrades this energy-saving potential. There’s therefore an increasing need for a full range of application-tailored optics.

Why should you choose fully application-tailored optics?


The right optic in your LED luminaire and lighting design can deliver the following:

  • Excellent performance—consistent, high-quality illumination.
  • Uniformity and full application coverage—light shines only where it's required.
  • Flexibility—various options and the ability to make changes in the field simply and easily.
  • Durability—delivering consistent performance and uniformity over time.
  • Designed to last—delivering consistent high-quality light even after LED upgrades, thereby ensuring optics will stay relevant during the entire lifetime of the installation. 
  • High efficiency—install costs are lower, as is power consumption.

Key questions to ask when evaluating optics quality:

 
  • How do the optics you’re considering satisfy the requirements of your application? Do they deliver uniform lighting distribution? If, for example, you want to illuminate a residential street, the luminaire in combination with the optic will have to throw uniform light across the entire surface – including the area that would potentially contain a pedestrian walking down the street.

 

  • Do the optics meet all relevant requirements? You need to be certain that the light distribution the optics generate meet all regional and national requirements, not to mention more local requirements and preferences. What, for instance, are the limitations regarding glare or light hinder in the neighborhood you’re working in? For that matter, the preferences of residents in certain neighborhoods might compel you to provide a higher quality of light than the rules strictly require.

 

  • Were the optics in question designed specifically for the luminaire you're using? The way your luminaire works in conjunction with your optic can have a significant impact on the performance of your lighting solution. Good design can ensure that light will shine only where it's intended to. Your luminaire needs to minimize spill light and light waste.

 

  • Have you selected optics that you can use across various products? This question is especially important when, for example, you’d like to illuminate a more geographically complex area using the same light distribution in different luminaires—some pole mounted and some suspended, for example, and of different sizes.  

 

  • How does the optic help reduce energy consumption? Municipalities, especially, have a stake in minimizing energy usage. Advanced, application-tailored optics use LED light more efficiently, mitigating energy-sapping issues like spill light. Such optics get the most out of every lumen.

 

  • How does the optic contribute to Total Cost of Ownership? Using the right optic, you can strike the right balance between maximizing luminaire spacing and selecting optical light performance, thus cutting down on the number of light points—reducing your maintenance work and lowering your energy consumption.

 

  • How do your optics stay up to date? One of the promises of LED lighting is that it lowers maintenance costs because of how long LEDs last. Digital lighting also brings the benefit of upgradability. For this reason, you need to select a solution that keeps the complete light engine’s lumen package the same even in the wake of a LED upgrade. That way you can extend your lighting scheme in the future even as you maintain the same lighting profile – thus lowering your energy bill.

 

  • How flexible are the optics? Between design and implementation, a lot can change in a lighting installation, so it makes sense to avoid a one-size-fits-all solution. Optical design flexibility, as well flexibility in the manner in which the solution is installed in the field (a luminaire can be installed with different tilt options, for example), lets designers make adjustments when necessary. And it lets them do so without their having to start over, add luminaires, or take other steps that incur extra expenses. Another way to boost flexibility is to add a back light louver, even after installation. It can prevent light from shining into nearby windows, for instance, thus cutting down on complaints.

Ledgine: Best in-class, flexible performance for both standard and dedicated outdoor projects


Clearly, the right optics choice is crucial to your ability to provide lighting that fully satisfies all of the needs of an application and the users in it. The right optics let you balance a variety of imperatives, from performance to reliability to costs to government requirements and beyond. Choosing it isn't to be taken lightly.

 

One ideal solution for future-proof and guaranteed optical performance is Philips Ledgine technology, a light engine platform which also offers a wide portfolio of application-tailored optics. Dedicated for varying needs, the new generation of Philips Ledgine offers a unique combination of standardization and customization, so you can tune lighting solutions to suit your exact needs.

 

Ledgine rests on three key building blocks:

1. Standardized, application-tailored optics across key portfolios  

 

A complete range of application-tailored optics ensures a perfect fit for every outdoor application. The optics offer flexibility, enabling standardization across applications and ensuring outstanding performance across a wide range of geometries in various applications, including high-traffic and less-used roads; tunnels; city centers and squares; and sports facilities. They're also capable of fulfilling design parameters related to such issues as tilt and overhang. They're easy to use and the distribution remains the same, so even after a LED upgrade you'll be assured of design continuity. In addition, they comply with all national and European road-lighting standards.

2. A high-performing standard engine across the portfolio

 

Using a standard engine across the portfolio means you'll benefit from the latest LED upgrades to various products without changing light distributions. The flux packages are pre-defined across product ranges, and include Constant Light Output (CLO) options. The products achieve flux minimization by using the highest lumen maintenance (up to L96) per standard. And for upgrades, the lighting image is continued and the engine is available for your installed base. The Philips Service tag application with built-in NFC technology also enables easy configuration of parts like drivers in the field.

 

The choice of optics can make a radical difference on the final result. Below you can see the example of a road lighting design using different optical solutions. Even though there is light everywhere on the road on the left image, you can see that the light is highly concentrated on the road, resulting in two effects. First, the pedestrian zone on the side is poorly lit, creating an uncomfortable and maybe even unsafe environment for pedestrians. And second, the concentration of the light on the road creates an undesired “tunnel” effect for drivers.

 

Even though the application of narrow optic may bring the desired reduction in terms of energy, we can clearly conclude that this is not the ideal solution for the users of the area. On the other hand, when you look at the image on the right-hand side, you can clearly see that in this case the pedestrian area is well lit, also providing comfort for users using that part of the application, as well as the bottom part of the facades to create a better ambiance in the neighborhood without disturbing citizens. 

Regular optical solution focused on delivering an energy efficient lighting plan
Application-tailored optical solution from Philips Ledgine, providing an energy efficient solution,  while considering the needs of the users in the area

3. The flexibility to tune flux levels to achieve an optimal result

 

Standard and pre-defined solutions make things easier — but there also has to be room for a bit of flexibility. To put it in conventional terms: Have you ever dreamed of having a 60W lamp in addition to the standard available 50W and 70W lamps? That's where solutions like the Philips L-Tune tool, available as part of the Ledgine package, can come in handy. Using L-Tune, you can customize your light source by tuning its flux.

 

The first step is simply to type into the L-Tune interface information regarding the selected luminaire and flux you’re using in your lighting calculation, as well as your preferences regarding lumen depreciation, LED operational lifetimes, dimming, and more. L-Tune then calculates different solutions for the same flux. You can choose from these the one that will achieve the best possible balance between cost, lifetime, and energy consumption.

 

L-Tune also helps you match your local requirements, which can be even more strict than regional ones in terms of the minimum lumen maintenance or power factor.Furthermore, to enable better serviceability, the newly defined L-Tune program codes are linked to the Philips Service tag application, so once you scan the luminaire's QR code you'll have access to accurate and up-to-date information on flux and power levels.

 

Optics innovations like Philips Ledgine allow for the highest-quality lighting in any outdoor application, from roadways to street-lighting to city centers and beyond. They meet the need for an up-to-date optics solution that makes one-size-fits-all technology immediately obsolete. Upgradeable, efficient, easily serviceable, and eminently versatile, they're sure-fire investments for municipal and infrastructure authorities, and will be powering the LED lighting revolution as it continues to develop across the decades of  breakthroughs ahead.

Towards a solution


Having checked off all of that, you’ll be ready to generate a design and provide or identify the following:
 

  • Light distribution efficiency (utilization factor): select the most efficient light distribution option that fulfills all your requirements. An extensive optics portfolio like the Philips Ledgine portfolio would cover all application needs.
  • The power consumption of your installation
  • The number of luminaires you’ll need, plus how they’ll be arranged and what spacing will be used.
  • The control settings you’ll require to coordinate how the tunnel will be lit throughout the 24-hour cycle: In addition to enabling dimming schedules, your control system should handle functionalities like fault detection or remote control.
     

This last phase, when your project really takes shape, will go the smoother if you’re regularly talking with different stakeholders to define the best solution.