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Photometric Testing

Sure, it's important what a lamp looks like. But in the world of lighting, it's more important to knowing what that lamp can do. It's especially important to lighting designers and electricians.

Light as graphs

You may have come across graphical representations like the ones you see below and wondered what they mean. Let's take a look:

Polar Curves Explained

Polor curve

An example of a polar curve


Beam cone

An example of a beam cone

A polar curve is a graphical representation of luminious intensity in different directions. The values are indicated in cd/klm (Candelas per 1000 Lumens) so are required to be multiplied by the luminous flux of the lamp used.

The solid line shows the distribution in the transverse plane. The dotted line shows the distribution in the axial plane. These curves give a visual guide as to the lighting distribution.

Beam Cones Explained

Beam cones indicate light's beam spread from a  luminaire. All Aurora cone widths are to 50% of peak beam illuminance. All values are real values as an average over the area shown with no maintenance factor applied.

These cones give you another style of visual guide as to the light distribution that the luminaire provides and are normally only used on direction lamps and fittings.

Tools of the trade

Special equipment has been developed which enable the collection of the data behind these graphs.

The Integrating Sphere in Aurora's Light Lab

As part of dedication to proving the lighting performance of our products, we've invested in both a goniophotometer and integrating sphere, contained within temperature and voltage controlled environments in compliance with LM79-8.

Aurora performs superior in-house testing with our own, state-of-the-art photometric sphere and gonio photometer. Our testing activities meet the requirements defined in LM79. The LM79 standard recognises that solid state LED lighting is evolving, and that the testing of these products must be standardised and still comparable. LM79 mandates the exact calibrations necessary and required product stabilisation procedures. We continually update our testing regime to stay ahead of any mandatory requirements and best practices. 


Our near-field imaging goniophotometer combines a motorised stage with an imaging photometer to perform near-field angular analysis of the luminance and colour from LED's. The internal software then scales this information to luminous intensity data from which photometric data files are created - either IENSA (ies) or ELUMDAT (ldt) format.

Integrating Sphere

Our Labsphere Light Measurement Integrating Sphere is designed for the measurement of the total flux output of lamps and other light sources. It's 76 inches in diameter with a highly relective, durable Spectraflect interior coating that can accommodate lamp sizes from sub-miniature incandescent and LED lamps up to a 4ft linear fluorescent lamp. It conforms to the recommendations of CIE publication 84.

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From polar curves and beam cones to goniophotometers and integrating spheres - It's all about proof of lighting performance!

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