Light metrology

Properties of light sources need to be determined accurately for various applications, for example in photometry and radiometry. This can be done by measuring the optical power of a beam of light with a specific wavelength.



Light can be measured for numerous applications, from interior lighting to marine lighting and from obstruction lighting to operating theatre lighting. It is important to accurately determine the properties of light sources in such areas as biological and pharmaceutical research.

VSL and light

VSL provides light measurement services across a broad spectrum, from infrared and visible to ultraviolet. Some applications are primarily concerned with human perception of light (photometry), while others focus on optical power per wavelength interval (radiometry).


We support and advise manufacturers and end users with regard to questions, enabling them to improve measurement and inspection methods to optimise the quality of their processes and products.

Would you like to know more about our services?

Our experts are happy to help.

Jaïr Blom
Sales Engineer

Optical measurements

To determine climate trends, we use optical instruments to make measurements both from the earth and from satellites. The raw data from these measurements are used to make climate predictions and models, among other things. Optical instruments must be professionally calibrated to ensure accurate and reliable data. VSL provides custom solutions for this, including radiometric classification of photodetectors, filter radiometers and array spectroradiometers.

Photobiological safety of lamps and lamp systems is a demanding field requiring cross-disciplinary knowledge and expertise. New developments in light sources are continually bringing about new complications in the measurement and evaluation of the relevant photobiological safety aspects. Traceable measurements play a crucial role in the photobiological assessment of these risks.


Custom metrology solutions for light

VSL has extensive knowledge of and experience in light measurement. Governments, hospitals, research institutes and manufacturers of light sources and measurement systems regularly ask our help with specific applications. Our measurement results are internationally recognised and provide strong substantiation of a product’s performance for customers and other stakeholders.

Our extensive testing facilities enable us to be of service in the following and other areas:

  • Classification of new light sources and detectors. We map out the spatial, spectral and time-dependent properties of newly developed light sources and detectors and compare them to the specifications.
  • Development and validation of measurement solutions.
  • Determination of measurement uncertainty and identification of measurement errors. Quantification of measurements by preparing an uncertainty budget and advising on the improvement of measurement uncertainty.
  • Advice on measurement methods in the light of laws and regulations. Laws and regulations are becoming increasingly technical. We outline how to make a measurement verifiable and assist in establishing meaningful requirements.
  • Independent opinions in claims and disputes. In claims and disputes, independent and reliable measurements can provide a definite answer.

Every situation is unique. Do you need advice or would you like to know what we can do for you? Don’t hesitate to contact us.


Light calibration services

VSL has extensive knowledge of and experience in optical measurements. We provide calibrations with very low measurement uncertainty. Our certifications are well known internationally and ensure worldwide acceptance of products and services. Given VSL’s independent position, our certificates are often used to substantiate specific product aspects, such as the efficiency and power factor of energy-efficient light sources. This can be useful when applying for an Energy Investment Allowance (Energie-investeringsaftrek), for example, which requires measurement in accordance with the LM-79-08 protocol.

Calibration of light measurement systems

Many lighting applications have their own specific light measurement system, which then needs to be calibrated under specific conditions. We have developed our optical measurement facilities in a way that enables us to calibrate a wide range of light measurement systems, such as luxmeters, luminance meters and cameras, tristimulus meters, spectroradiometers, UV meters, laser power meters and semiconductor detectors.

Measuring light sources

VSL can use its measurement facilities to measure specific, optical properties of light sources over a wide spectral range. These include radiometric, photometric and colorimetric (colour-related) properties, such as spectral irradiance, total spectral radiance, luminous flux, illuminance, luminance, correlated colour temperature, colour coordinates and RA value.

At the same time, we can measure the desired electrical properties of a light source or a combination of electrical and photometric properties, such as the specific luminous flux (also called luminous efficacy, denoted in lm/W). VSL’s measurement facilities are able to handle a variety of light sources, e.g. navigation lighting, signal lighting, operating theatre lighting, horticultural lighting, street lighting and utility lighting.

Calibration of optical filters

VSL performs application-specific calibrations of optical filters, such as for the automotive and pharmaceutical industries. The results are used for traceability of optical transmission and wavelength. We express calibration results as spectrally resolved transmission, colour shift, opacity or wavelength of maximum absorption.

Our areas of expertise