LED optical systems
Optical principle The light is guided by three elements in an ERCO LED spotlight: the primary lens which is directly mounted on the LED chip and produces a semi-spherical beam, the secondary lens in the form of a collimating lens to create a parallel beam and the tertiary lens in the form of a Spherolit lens. The design of the tertiary lens determines the actual light distribution for the specific application.
Collimating lens For all characteristics - except for narrow spot - the three-piece collimating lens is suitable for the module with three LEDs. The beam is controlled by total internal reflection at the sides and by the central lens. Precise mounting points result in secure and effective mounting.
Collimating lens for narrow spot The appropriate collimating lens is used with LED spotlights and projectors with the narrow spot characteristic. Its function is solely based on the optical principle of total internal reflection, which contributes to the high efficiency of the optical system.
Total internal reflection
Spherolit lens
Total internal reflection
Due to its shape and material, the collimating lens for narrow spot directs the light with practically no losses using the principle of total internal reflection. This results in optimum light guidance efficiency.
After focusing the beam through the collimating lens, it is the Spherolit tertiary lens that determines the light distribution. This ranges from narrow beams to wide beams and asymmetric light distributions for vertical illuminance.
Development
With extensive experience in optical simulations, ERCO identifies innovative solutions for new challenges such as the development of highly efficient lens systems.
Short distances for optimum quality: photometric laboratories, tool shop and production department for the optical systems are all located on the same site. This allows for rapid comparison of computer simulations, prototypes and fabricated components.
Projection and reflection
Conventional point light sources emit light in a solid angle of virtually 360°, whereas the inherent design of LEDs means their light is directed in a solid angle of <180°. The result is reduced losses due to spill light or light emitted towards the lampholder (shown red in the drawing). Furthermore, the higher transmission efficiency of lenses compared to that of reflectors produces a higher light output ratio which results in the greater luminous flux from the luminaire. In practice it comes down to how much light arrives on the target surface. In this respect, the illuminance from spotlights which have similar characteristics can be compared over a given distance in lx/W: the principle of projection with LEDs continues to be convincing.
Projection: Spherolit lenses
With LED lighting tools for directed light, ERCO uses Spherolit lenses as tertiary lenses to direct the light. In terms of their technology and light distribution, the Spherolit lenses are based on the patented Spherolit reflectors which are well established with conventional light sources. In addition to excellent lighting quality, they also offer many practical advantages for both lighting designers and users. The Spherolit technology is based on dividing a large lens or reflector surface into many individual, three-dimensionally domed facets, each of which directs the light through refraction or reflection. The transmission of light through the polymer Spherolit lens has fundamentally lower losses than with reflection. At ERCO, the manufacturing processes all take place under one roof: from complex calculations and computer simulations to tooling up and final production.
Characteristics with Spherolit lenses
Narrow spot To accentuate small objects with high light intensity or to cover large distances between luminaire and object. Beam angle < 10°.
Spot
The standard characteristic for accent lighting for objects of all kinds, especially to reveal the three-dimensional shape.
Beam angle: 10° - 20°.
Flood
To efficiently illuminate larger objects or to emphasise spatial zones such as a specific area.
Beam angle
25° - 35°.
Wide flood To give a flexible, flood illumination of surfaces and spatial zones, especially in retail presentation. Beam angle> 45°.
Oval flood The Spherolit lens, oval flood, has an axially symmetrical light intensity distribution, producing an oval beam of about 30° by 90°.
Wallwash The light distribution of the lens wallwasher has been optimized to provide excellent uniformity.
Spherolit lens toolmaking
Toolmaking ERCO has its own toolmakers´ shop featuring state-of-the-art equipment and backed up by decades of experience. This guarantees the necessary precision when machining items such as injection-moulding tools used to make optical elements from polymers.
Thermoplastic injection moulding Cutting-edge injection-moulding machines, qualified employees, high-quality raw materials and careful checking all contribute to the perfect quality of ERCO´s collimating and Spherolit lenses.
Assembly The luminaires of the Quintessence product range, such as the directional luminaire shown here, are assembled to order using advanced production principles.
Spherolit lenses
By designing the shape of each Spherolit lens individually, a wide range of lens characteristics can be created. The parallel incident light is spread to a greater or lesser extent depending on the curvature of the surface. This results in lenses that have different beam angles, ranging from narrow spot to wide flood, yet retain the same overall geometry. In addition, asymmetrical spherolites enable oval beams and wallwashing lenses. A common feature of all these beam characteristics is light of the highest quality: the beams are particularly uniform, free of striations and have a clean, slightly soft edge.
SpotThe Spherolit lens, spot, has flat Spherolit surfaces producing low dispersion for a narrow beam angle.
Wide floodThe wide flood Spherolit lens has the greatest curvature. The wide spread produces a beam with a large emission angle.
Spherolitoptik für varychrome RGBW-Strahler Eine zusätzliche Ebene im optischen System dient zur vollständigen Mischung des farbigen Lichtes, noch bevor es von Kollimator und Spherolitlinse zum gewünschten Lichtkegel geformt wird. Das Resultat: LED-Licht mit beliebigen Farbtönen und Farbtemperaturen, völlig frei von irritierenden Farbschatten.
Indirect step lighting
With step lighting, it is imperative that the LEDs are well screened to ensure that there is no glare for people going up the stairs. In the Axis Walklight, the light guidance takes place indirectly. The LED module is concealed from view.
Manufacture of Spherolit reflector
The patented Spherolit reflectors are of pressed aluminium. Their innovative technology requires the highest precision and calls for a new approach both in toolmaking and in the manufacturing process.
The finished Quintessence luminaire
is built to order from a combination of LED module and a lower reflector unit. Here, innovative technology such as "Pick by Light" shelves ensure error-free order completion.
Cut-off angle and Darklight technology
A cut-off angle of 30° (left) provides good uniformity on the floor with a very high lighting output ratio.
Luminaires with a cut-off angle of 40° (right) provide higher visual comfort. This can also be seen from the UGR values in the product data sheets. If the observer is in the cut-off area of the luminaire, the reflector will appear glare free.
With their computer-generated contours, ERCO's low-brightness reflectors combine maximum visual comfort with a high light-output ratio. As long as the lamp is within the cut-off area, there is virtually no luminance on the low-brightness reflector to ensure the eye is not blinded. For optimal visual comfort, the higher cut-off angle is recommended for prestigious rooms with high ceilings or for deskwork The UGR process (Unified Glare Rating) quantitatively evaluates psychological glare. A downlight with a cut-off angle of 40° from horizontal and a UGR value of 17.3 provides more visual comfort than an otherwise identical luminaire with a 30° cut-off angle and a UGR of 19.0.
By using dedicated PCB layouts equipped with carefully selected LED binnings, ERCO ensures that optimum luminous flux and colour rendition is obtained for each specific lighting task.
The optical systems for LED lighting tools are vastly different from those of conventional luminaires. ERCO designs and builds these systems in-house to ensure a perfect match, thereby allowing their full potential to be exploited in terms of efficiency and lighting quality.
ERCO places particular importance on heat management. This ensures that LED modules operate within their safe temperature range, achieving rated life and output for the specified power throughout their operational life.
LEDs require perfectly matching electronic control gear. Only ERCO´s factory encoded DALI control gear offer plug and play connectivity, i.e. fully automatic recognition in the Light System DALI lighting system.
LEDs and digital lighting controls such as Light System DALI are truly made for each other. No other light source can be controlled as flexibly and efficiently as an LED. The user-friendly operation through lighting control allows great scope to design scenographic lighting in the sense of "tune the light", this enables the potential energy saving to be fully realised.
