​​​​​About

The Photometry and Radiometry section is responsible for maintaining the SI unit for luminous intensity, the candela, and to provide traceable radiometric and photometric measurements and calibrations in support of various industries and fields, such as: 

• Lightin​​g
  

• Aero​​space

• Health a​​​nd Safety

• Manufactu​​ring

• Automoti​​ve industry

• Agricult​​ure

• Resea​rch

These measurements and calibrations impact aspects of everyday life such as energy-efficiency and quality of life. 

Key Facts​​​​​

The science of photometry and radiometry addresses the measurement of electromagnetic radiation. In more general terms, photometry concerns the measurement of light, i.e. the visible part of the electromagnetic spectrum. Measurements are performed in such a way that the response of the human eye to visible light is considered. Radiometry, on the other hand, concerns the measurement of electromagnetic radiation in the much wider spectral region ranging from the ultraviolet to the infrared part of the spectrum.

Photometric and radiometric measurements are important in a very diverse range of applications, including:

• the lighting of homes, shops, factories, streets, and other public areas,

• signaling for road, rail, sea and air transport,

• process control in industries such as printing, plastics, textiles, paints, food, manufacturing and pharmaceuticals,

• medical treatments such as phototherapy,

• air and water disinfection,

• curing of resins,

• non-destructive testing (NDT),

• earth-observation,

• agriculture and

• material characterisation.

​​As the number of applications increase, so does the need for increasingly accurate photometric and radiometric measurements of sources, detectors, and materials.​

The Photometry and Radiometry section offers measurement and calibration services that are categorised

• Photometry

• Properties of detectors (radiometry)

• Spectral emission properties of sources (spectroradiometry)

• Spectral properties of materials (spectrophotometry)

• Spectrally integrated measurements for sources and detectors
  

Colour and other spectrally integrated measurements of materials (colorimetry). The Photometry and Radiometry section has close links with the International Commission on Illumination (CIE). This involvement is enhanced by participation in the activities of the Illumination Engineering Society of South Africa (IESSA) who represents the CIE in South Africa. IESSA keeps all stakeholders with interests in lighting and related matters informed of CIE recommendations and proceedings to ensure that the South African industry benefits from international developments. 

Furthermore, we participate in international key comparisons with other international laboratories, thereby maintaining the National Measurement Standards in photometry and radiometry as mandated through the Measurement Units and Measurement Standards Act (Act No 18, 2006) and assuring comparability internationally. Our internationally recognised calibration and measurement capabilities (CMC) are peer-reviewed and listed in the key comparison database(KCDB) of the International Bureau of Weights and Measures (BIPM).

We are also an accredited calibration laboratory with the South African National Accreditation Service (SANAS) according to the ISO/IEC 17025 international standard.

How we can help

The Photometry and Radiometry section can perform the following measurements and calibrations: 

Photometry:

• Luminous intensity of sources 
  

• Averaged luminous intensity of LED sources

• Illuminance responsivity of illuminance/lux meters (photometers)

• Luminous flux of sources

• Illuminance of sources

• Luminance of sources

• Luminance responsivity of luminance meters

Properties of detectors:

• Spectral power responsivity of broadband and black thermal detectors

• Spectral irradiance responsivity of broadband and black thermal detectors

• Spectral radiance responsivity of spectroradiometers

• Optical/laser power responsivity

• UV broadband irradiance responsivity (UV-A, UV-B, and UV-C meters)
  

Spectral emission properties of sources:

• Spectral irradiance (various sources)

• Spectral radiance (various sources)

Spectral properties of materials:

• Spectral transmittance (regular and diffuse)

• Spectral reflectance (-diffuse)

• Spectral absorbance (regular)

• Wavelength

Spectrally-integrated measurements for sources and detectors:

• Correlated colour temperature of a source

• Emitted colour of a source

• Chromaticity response of a colorimeter

Colour and other spectrally-integrated measurements of materials:

• Surface colour

• Transmitted colour

• Luminance factor​
  

Please check our SANAS schedule of accreditation for a list of accredited services:

https://www.sanas.co.za/Pages/index.aspx

We can also offer advice on your photometry and radiometry questions during product development or the research phase of your lighting or radiometry project. Please contact us to discuss your needs and how we can be of service.​

Development Proj​​ects

The Photometry and Radiometry section is developing measurement capabilities for light-emitting diode (LED) products that serve as energy efficient light sources. The move towards LED lighting is propelled by its high efficiency which promises savings in terms of energy and cost. In order to support the local lighting industry, accurate LED measurement methods and standards must be developed to ensure that its performance can be assessed correctly. The development and implementation of a national measurement capability for LED products to support the energy saving drive in South Africa is one of NMISA’s top priorities. The Photometry and Radiometry section can currently measure the following properties of small to medium-sized LED products:

Photometric and radiometric

• Spectral power distribution

• Spectral radiant/luminous flux[IR1] ,

• Radiant/Luminous flux

• Chromaticity coordinates (x, y), etc.,

• Correlated colour temperature (CCT),

• Colour rendering index (CRI),
  

• Luminous intensity,
  

• Averaged LED luminous intensity[IR2] [PDT3] ,

• Irradiance/Illuminance,

• Radiance/Luminance, 

• Peak/Centroid/Dominant wavelength,

• Purity,

• ​Half width
  

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