The Science of Goniophotometry
Introduction
At Raytec, we are dedicated to producing LED lighting solutions that excel in performance, efficiency, and reliability. One of the most fundamental aspects of this process is measuring the photometric characteristics – a task we accomplish with the help of our in-house Goniophotometer.
What is a Goniophotometer?
A Goniophotometer is a highly specialised device used to measure the photometric or radiometric performance of lighting products. It consists of two key elements: a photometer or spectro radiometer and a goniometric motion stage. The photometer or spectro radiometer measures the properties of the light source while the goniometer rotates and tilts the light source about a fixed photometric centre.
How is it used?
The Goniophotometer uses advanced components such as:
- A Spectroradiometer Sensor: To analyse the spectral and radiometric characteristics of the emitted light.
- A Power Analyser: To monitor and measure energy consumption.
- A Revolving Arm: To capture light data across multiple angles, creating a comprehensive profile of light distribution.
This meticulous process allows us to examine the interplay between energy consumption and light output, enabling precise adjustments to enhance overall efficiency. To assess lighting performance comprehensively, the Goniophotometer provides key measurements including:
- Luminous Flux: The total amount of light emitted by a luminaire in all directions as perceived by the human eye. Provides a measure of overall power of the luminaire.
- Light Intensity Distribution: The measuring of light intensity in relation to angle from the luminaire. This shows how the luminaire directs and controls the available light to illuminate a space.
- Spectral Power Distribution: Measuring of power of light in relation to wavelength emitted by the luminaire. This shows how the overall light emitted by the luminaire is made up by the different colours of the spectrum.
- Efficacy: The ratio of emitted light from the luminaire compared to the input power.
- CCT (Correlated Colour Temperature): Indicates the colour appearance of the light, ranging from warm (yellowish) to cool (bluish) tones, measured in Kelvins.
- CRI (Colour Rendering Index): Measures how accurately the light source reveals the true colours of objects compared to natural light, on a scale from 0 to 100.
These insights are critical for ensuring that each of our products meets the highest standards of performance and is tailored to a wide range of applications.
Why Measure Light Intensity?
Not only does the data provide key metrics for quantifying the performance, but is also used to generate photometric data files. These files are created in either IES or EULUMDAT (ldt) format and can be imported into lighting design software packages to accurately simulate the real world application of the product – whether its illuminating a warehouse, an offshore rig, or a wind farm.
What Do We Do with Photometric Data?
The photometric data generated by our in-house goniophotometer serves multiple key functions:
- Design Optimisation: Engineers can tweak reflectors, diffusers, lenses, and housing materials to achieve the desired light distribution and efficiency.
- Product Comparison & Benchmarking: Accurate data makes it easier to compare different lighting solutions and ensure consistency across product lines.
- Simulation & Planning: Our Lighting designers can use photometric files in simulation software to model how a fixture will perform in a given space.
- Compliance & Certification: Photometric data is often required to meet industry standards and certifications, ensuring the product adheres to energy efficiency, safety, and performance regulations.
- Customer Confidence: Transparent, data-backed performance boosts trust in the product’s real-world effectiveness.
Measuring light intensity gives us the technical clarity needed to create better lighting products, predict how they’ll behave in the field, and deliver solutions that meet both design goals and regulatory requirements.
Measuring Infra-Red for Security Applications
While most lighting measurements focus on visible or white light and are expressed in photometric units such as lumens or lux, not all light is visible to the naked eye. Infra-red (IR) light, for example, plays a crucial role in surveillance and security applications, particularly in low-light or nighttime environments.
Because the human eye cannot detect infra-red, we measure it differently. Instead of photometric units, IR performance is measured in radiometric units like watts, which quantify the total energy emitted regardless of human visual response. This ensures accurate evaluation of the IR output used in technologies such as CCTV systems or perimeter detection, where visibility to a camera, not the human eye, is paramount.
Our in-house Goniophotometer is thus also capable of testing IR lighting. This allows us to fine-tune our security products to deliver optimal performance under a wide range of conditions.
Benefits of In-House Measurement
At Raytec, we believe in integrating advanced technologies directly into our production processes. By housing a Goniophotometer in our factory, we’ve significantly improved both our efficiency and flexibility. Here’s how:
- Enhanced Innovation: The ability to test performance in-house allows our engineers more time to refine designs and innovate.
- Speed to Market: Internal testing accelerates the development process, enabling quicker rollouts of new products.
- Customisation: With detailed performance data at our fingertips, we can adapt our designs to meet the specific needs of our customers across various industries.
Lighting Design
When installing a professional lighting system, we always recommend using a professional lighting design service. A professional lighting design service provides the end user and installer with a detailed report that shows the lighting levels that will be achieved on-site. This ensures there are no surprises at the point of commissioning and acts as a guide during installation, reducing installation time.
Our award-winning, free-of-charge lighting design service offers full site modelling and detailed reports for both White Light and Infra-Red applications, bringing to life new installations for Hazardous, Industrial, Security and Transport applications. Contact us today to learn more.
Lighting the Way Forward
With our Goniophotometer, we can measure the performance of our products in-house, significantly improving efficiency and flexibility. This allows us more time to innovate and develop a diverse range of products.
The Goniophotometer is a cornerstone of our commitment to excellence. By leveraging this technology, we continue to push the boundaries of LED lighting design, delivering products that perform optimally while maintaining energy efficiency.
At Raytec, innovation is a standard we take pride in. Through investments in advanced tools like the Goniophotometer, we remain at the forefront of the lighting industry, illuminating spaces and ideas with precision and purpose.