LED chips are a one-dimensional light source that emit a 180° dispersion of light. This 180° dispersion is too broad for most practical applications as it lacks the intensity we need for light to travel between a light fitting and an interior surface.
Therefore, in order to harness the light produced by an LED, we require a secondary component, namely a reflector or lens.
What is a reflector?
A reflector is a traditional method of controlling a beam of light.
It is an OPEN cone component fitted around an LED chip to alter the direction of its broadest light rays.
It often produced from plastic, metal or glass and features a solid internal coating. The internal surface may be smooth or multifaceted depending on the desired lighting effect.
Reflectors do not absorb light. Any light that touches the surface is efficiently reflected.
However, the design of a reflector does allow the central rays of light produced by an LED chip to pass through unaltered. (Figure 1)
As a result, even a narrow reflector will allow some light rays to stray wider than then intended over long distances.
What is a lens?
A lens is an advanced method of controlling a beam of light.
A lens is a SOLID plastic form that works on the principle of refraction.
The solid nature of this component covers the entire LED chip, capturing and controlling all emitted light rays.
A lens controls light in two stages.
Firstly, a concave moulding at the centre of the lens, directly above the LED chip, folds the central light rays outwards, allowing them to be captured in the second stage.
Secondly, the outer moulding of the lens collects the widest rays of light, along with the rays folded outward in the first stage, and reflects them inward to achieve the desired beam angle. (Figure 2)
Therefore, lenses are very effective at controlling light, even over greater distances.
Core advantages and disadvantages
Reflectors
Advantages - Good efficacy and relatively low cost
Disadvantages - Much lower control of accuracy, particularly in narrow beam angles.
Lenses
Advantages - A high degree of accuracy and reduced glare
Disadvantages - A minor reduction in efficacy
Making the right choice
Both lenses and reflectors have their place in the lighting world. However, thanks to their effectiveness, glare reduction and design flexibility, lenses will establish their dominance in the years to come.
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