The light coming from an LED’s primary optic is not suited for most applications; it is too broad and lacks intensity over a distance. As such the beam of light can be altered by a secondary optic. In this article we discuss the various types of secondary LED optics.
Primary LED optics
Light coming from an LEDs primary optic is what is referred to as a typical spatial distribution. LEDs face one direction, so imagine a line going down from the center. Spatial distribution is measured in degrees from this center point. Each optic has a beam that will extend to either side of this center point. This means you will not get the entire lumen output from the LED across the whole spectrum. The closer to the center, the stronger the light. Along the center axis the LED emits all of its relative luminous intensity. Intensity is lost the farther away you move from the center. As such, a lot of light output over the spectrum is being lost, hence the use of a secondary optic is required to intensify the light. With a secondary optic the brightness and efficiency of LEDs can be used to their full capacity.
Types of secondary LED optics
There are three types of secondary LED optics:
- Total internal reflectors (TIRs)
A secondary LED optic collimates all the light from the source and magnifies its intensity towards the target. Secondary optics can also be used to improve color uniformity and light distribution within a targeted area.
Choosing the right secondary LED optic depends on the application. LED lenses are available in all shapes and sizes. They can be round, square, or hexagonal, whereas reflectors can have varying cone shapes. With Addoptics’ technology you are even able to create freeform optics.
Types of LED optics
TIR optics were originally intended for outdoor applications. However, nowadays you will also find them for indoor usage. Total Internal Reflectors work best with narrow beams. With a TIR optic you are able to direct the light beam. TIR optics make use of a refractive optic inside a reflector to control the spread of light efficiently.
Reflectors are available in all shapes and sizes. This enables them to create a whole range of lighting effects. The way they collect and disperse the light depends on their shape. . A typical reflector has a polycarbonate molding with a metallized reflective coating. The metallized coating helps achieve high reflectance, but at the cost of beam control.
One downside of reflectors is that the majority of light rays coming from the LED will not hit the reflector. Meaning you will have a large amount of light which will not hit the intended target which creates glare. In such cases a TIR optic would be a better option.
Lens arrays are ideal for projection systems and illumination. With lens arrays you can create an even illumination. When used in pairs they provide an even brightness across the illuminated field.
Fresnel lenses are a special kind of optical lens. The surface profile contains annular steps which enable a specific focal length while drastically reducing lens thickness. The more annular steps the Fresnel lens has, the thinner the optic can be made. This makes Fresnel lenses ideal for optics that have a large diameter and dioptric power. Originally the Fresnel lens was used for lighthouses, where the generated light had to be redirected with a relatively compact optical setup.
This type of lens is most commonly used in the area of illumination, like condensers in overhead projectors, traffic lights and for concentrating solar power.
Micro-optics are optical optics with a very small diameter (<1mm). A common application of this type of lens are micro-lens arrays, where are fabricated together on a common substrate. Applications of micro-lens arrays include the collimation of the output of arrays of waveguides.
This type of optic has an optical design with at least one freeform surface. According to the ISO standard 17450-1:2011, a freeform lens has no translational or rotational symmetry about axes normal to the mean plane. Freeform optics have been used since 1990 in the areas of illumination and non-imaging optics. Integration of freeform optics and freeform surfaces used to be a major challenge and would necessitate long lead times. Thanks to Addoptics’ unique manufacturing process, you are now able to have your custom freeform optics created in a matter of days.
Creating the perfect LED optic for your project
Most of the time LED optics that are available in stock are not optimal for a specific project. In addition, making design changes to exisiting optics can prove to be costly. Fortunately, you no longer have to settle for this suboptimal approach, as we offer smart manufacturing of polymer optics. This means you can improve your optics design based on your needs and have them manufactured in a matter of days.
As an example of our capabilities, you can have 10 different products where each product has a slightly different design. No high upfront costs, short lead times, and more design freedom. With our unique technology we are able to have your custom optics shipped to you in a couple of days. Curious? Request your sample here.