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LED Optical: The Basics and Importance

Is an LED optical important? After all, LEDs come with primary optics. Well, let’s talk about the primary optics first.

The primary optics of an LED PCB is a little protective dome. And it’s usually over the diode. The optics help to protect the diode. Plus, it outlines the small diode’s output.

The primary optic produces light that is too wide—which isn’t ideal for most applications. Now, this is where secondary optic is vital.

So, the answer to the question is yes—LED optical is necessary. And it’s because secondary optics help to pull light together and boost its strength towards the target.

Do you want to know more? Let’s begin.


What Are The Types of LED Optical Systems?


LED Optical


Now that you have an idea of what an LED optical is, let’s look at the types we have:


Primary Systems Joined to Integrated Lenses - Special Beam Angles


This optical system distributes or emits light at different angles. So, we have different angle spreads ranging from 4 to 120 degrees or more.

The very wide flood emits 50 to 120 degrees or more. While the wide flood emits 36 to 49 degrees. Also, flood and spot emit light at 20 to 35 degrees and 4 to 19 degrees respectively.

In other words, the primary systems with integrated lenses surround a particular spot with light.

So, what’s the difference between the different angles the optics system covers?

The smaller angles mean that the light beam won’t reach far. But the larger angles mean that the light beam will be broad with low intensity. And it’s because the broad beams are farther away from the center.


Secondary Optical Systems Organized as Diffusers, Reflectors, or Lenses


The secondary optical system assembles all the light that comes from a certain source. Afterward, it expands the light’s intensity close to the target.

How does it assemble light rays with full intensity in a particular area? First off, the light rays from secondary optics spread in parallel.

But, you shouldn’t expect a perfect parallel. Why? Simple. It’s because of the limited physical size of the bare emitter and diffraction. Also, if you want a more effective process, ensure that your emitter is small.

So, you can use this optical system to distribute light in a targeted area. Also, it’s useful for boosting color uniformity. A good example of secondary optics is a reflector.


Primary and Secondary Optics Combined for Special Applications


This optical system gives a better result. And it’s because a primary optic lacks intensity over distance.

So, using the primary optics alongside secondary optics will help diffuse emitted light. In other words, using this optical system means that your LED will emit light with increased intensity.


Choosing Lenses to Make the Most of LED Optical Performance


Before you settle for a lens that will provide the best LED optical performance, it’s best to consider the following factors:


LED Lens Types 


What kind of lens is ideal? First off, you have to consider if it will work for your application. Then, weigh the pros and cons of each lens. That way, you’ll know if it’s the best option.

So, here are some lenses you can choose from:




Reflectors are easy to use. And you need to consider the shape. That way, you’ll know how well it will assemble light into parallel rays.

What if you need it to further diffuse light? In this case, you can facet the surface. Therefore, it will enhance beam uniformity. And you can also use different finishes or textures.

With that in mind, you should also know that reflectors don’t give a complete solution.

How? For instance, you may have a glare or spill light. This issue occurs when light from an LED avoids a parabolic reflector. In other words, most of the light rays from the LED won’t hit the target.

Also, a lot of reflectors come with a metalized reflective coat and polycarbonate molding. The coating doesn’t have beam control. But, it offers high reflectance.


TIR Optics


Initially, TIR optics were for outdoor applications. But these days, people use them indoors as well. The TIR optics allows you to direct the light beam. Plus, it works perfectly with narrow beams.

Also, the TIR optics controls the spread light effectively thanks to its refractive optic in a reflector.


Fresnel Lenses


The Fresnel lens is ideal if you deal with illumination like traffic lights, condensers in overhead projectors, etc. This unique lens has a surface profile with annular steps. With that, you can use a certain focal length while reducing the lens thickness.

So, you can make the optic thinner if the lens has more annular steps. Also, you can use this lens for optics with dioptric power and a large diameter.


Lens arrays


This type of lens is perfect for illumination and projection systems. Plus, it allows you to create uniform illumination. If you want to create a smooth brightness across the illumination field, use the lens in pairs.




The micro-optics are ideal for applications like the assembly of the output waveguide arrays. As the name suggests, it has a small diameter.


Size is Important


Did you know that you can determine the beam angle from the size ratio of an LED to an optic? In other words, you’ll need larger optics or smaller light sources for narrow beams.

But due to a need for ease and higher luminous flux, there’s an increase in source sizes. As a result, LED producers planned to interest fixture designers. And they introduced high-output COB (chip-on-board) LED arrays.

The COB LEDs are a thing these days and they have multiple dies. The die works as one electrical device. And the die is usually in a ceramic package alongside one emitting surface.

But it’s tough to control the output of COB LEDs. Plus, its flat surface doesn’t couple properly. In summary, COB arrays are ideal for applications that need little beam control like downlighting.

The High-flux density LEDs aren’t left as well. It also has multiple dies like the COB array. But the die is smaller. And the HFD LEDs produce more light output. Plus, it does this from a small light-emitting surface.

These LEDs can house a TIR optic with ease and the die stays in a domed surface. So, it means that the HRF LEDs will provide increased output control.


Taking the Heat


With the rate at which HFD LEDs and COB have increased lumen output, it means one thing: there’ll be more heat. As a result, the sources will need adequate thermal management. That way, the fixture circuitry, and the diode will last longer.

Coupling is another way to enhance optical efficiency. But, subjection to heat and light can result in material degradation in the long run. For instance, manufacturers use LED-grade materials because it withstands prolonged heat exposure. Plus, it has good clarity and transmits light adequately.


Bottom Line


If you aim to pull your light together and boost it to hit the target, you need LED optical. And from the look of things, it isn’t rocket science to get one.

All you need to do is be clear about your applications. Then, weigh the pros and cons of your choice. That way, you’ll make a good decision.

What do you think about LED optical? Do you have questions or suggestions? We’ll love to hear from you.