How Raytec Calculate Illumination Angles?


14 September 2017

The spread of light from your illuminator has a critical impact on the success of your video surveillance system.

But in the absence of any accepted industry standards and testing methods the calculation of Width/Angle has historically been left open to the interpretation of the manufacturer – leading to varying performance claims.

This has always made it virtually impossible for consultants, installers and end-users to specify surveillance lighting with confidence, reliably compare products, and achieve a consistent level of performance.

Width/Angle Performance

Consider the two images above, both manufacturers could claim a 60° beam angle.

Whilst the manufacturer on the left could technically claim that their illuminator does actually provide light throughout the full scene, we can clearly see that the image on the right is far superior, evenly covering the full width and depth of the scene with no dark or bright areas.

So how should illumination angle be calculated?

Until now there has been no standardised way to evaluate performance claims of different illuminators. And crucially, there have been no standardised testing methods for manufacturers to adhere to. As the world leader in LED surveillance lighting Raytec have taken the lead in publishing the industry’s first Lighting Standard for Video Surveillance – POWERS.

  • POWERS sets a performance benchmark
  • Uses consistent scientific testing methods
  • Highlights relevant criteria to consider
  • Explains how your illuminator will perform

Based on decades of practical industry experience “POWERS” tackles the issue of calculating illumination angle head on. With POWERS we’re proud to tell you what WE recommend as an industry benchmark and how you can use this to calculate how wide your illuminator will TRULY shine.


When looking at an illuminator, customers ultimately want to know: how far and how wide does it shine, is it efficient and reliable, what features does it have and what level of warranty, certification and technical support will the manufacturer provide?

The Raytec “POWERS” standard answers these questions by looking at the following areas:

P Peak Power
O Overall Power
W Width/Angle
E Environmental
R Reliability
S Specification/Features

Surveillance lighting standardisation is a highly detailed and very topical subject. However, this article only focuses on the ‘W’ of POWERS which proposes a scientific approach to calculating the width/angle –a crucial element in determining your illuminator’s true performance.

Our Width/Angle Calculations

A standard measurement to determine width/angle is the ‘Full Width, Half Maximum’ (FWHM) approach.

It is well-known in many traditional lighting industries and this is the approach adopted in the POWERS standard. It takes the peak power reading in the centre point of the beam and then records the angle at either side of centre at which lighting power has dropped to 50%. This measurement helps to provide an understanding of the beam angle provided by the illuminator.

FWHM determines maximum width/ angle by measuring the point at which lighting power has dropped to 50%, either side of the centre beam point.

Raytec quote our angles based on 50% of the peak power. The Raytec POWERS standard provides information on the angles achieved at BOTH 50% and 25% of peak power to offer more data for specifiers.

With this data, you will be able to accurately evaluate the quality of the beam spread and it will help you to understand how to reliably compare the angle output of different lighting products.

Specify with Confidence

Want to be sure that your illuminator is going to deliver what it promises? Ask us for POWERS Specification Data for our VARIO2 illuminators and specify your lighting installation with confidence.

We guarantee that every Raytec illuminator delivers a minimum of 0.35μW/cm2  (Infra-Red) or 3 lux (White-Light) power on scene at our maximum quoted distance – ensuring the best image quality every time.

If your manufacturer can’t tell you how they’ve calculated their distances – how can you trust their claims?

In addition, Raytec can provide testing of third party products in accordance with the POWERS standard, so where there is no published information available, Raytec will measure the product and provide the relevant information.

Explore our complete range of VARIO2 Infra-Red and White-Light illuminators here – or drop us a line to speak to a Raytec expert about POWERS, your current lighting project, or any other lighting matter. We love to talk lighting!

Call us: +44 (0) 1670 520055
Email us:

Interested in learning more about POWERS? Download the E-Book

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