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Luminance standards and radiance standards are used in photometry and radiometry, in particular for the calibration and characterization of cameras and optical measuring devices. Another application is the determination of reflection, transmission and absorption properties of materials. 

Luminance and radiance standards are homogeneous light sources that have a uniform brightness over their entire emitting surface and emit almost perfectly lambent and uniformly in all directions. 

The mode of operation is based on the principle of the integrating sphere. The integrating sphere consists of a hollow, spherical structure with a highly reflective inner surface. This surface is coated with a diffuse reflective coating of barium sulphate, which scatters almost 100% of the incident light. This property enables the sphere to distribute the light evenly in all directions and eliminate directional effects.

For luminance standards and radiance standards, the light sources are positioned outside and shine into the sphere.


Each Opsytec integrating sphere is manufactured to the customer‘s individual requirements to ensure optimum performance for specific applications.
Another feature of the luminance and radiance standards from Opsytec Dr. Gröbel GmbH is their ability to integrate multiple light sources simultaneously. These can optionally be operated individually or in groups and can be dimmed or fitted with a manual or motorized mechanical diaphragm. Shades are used if the luminance and radiance levels need to be adjusted but the lamps cannot be dimmed or change spectrally.

The following lamps are possible as homogeneous light sources for luminance or radiance standards:

Halogen lamps are commonly used because they offer a continuous spectrum in the visible range. They are ideal for applications that require high color fidelity and a continuous spectrum. Halogen lamps are also available in different wattages, allowing flexibility of choice.

Light emitting diodes (LEDs) are increasingly being used for luminance standards and radiance standards. LEDs offer several advantages, including long life, energy efficiency and the ability to select specific wavelengths. LEDs enable precise control of light intensity and a fast response time, which makes them particularly attractive for modern applications. The luminance achieved is higher than that of conventional integrating spheres with halogen lamps.

Deuterium lamps produce a continuous spectrum from about 200 to 400 nm, making them ideal for applications requiring UV radiation. 

IR emitters, such as tungsten emitters, produce a continuous spectrum with a maximum in the near to mid infrared range and are often used in IR spectroscopy and thermography. IR emitters are also available for vacuum applications.

These lamps are used as luminance and radiance standards in the following homogeneous light source applications:

  • Calibration of measuring devices for luminance and radiance
  • Generation of a homogeneous light source with defined luminance values for the characterization of camera systems
  • Provision of reference values for quality control in the lighting industry
  • Supporting research and development in the field of optics and photometry
  • Characterization of reflection, transmission and absorption, where uniform illumination ensures the results.

Technical data, accessories & holders for luminance / radiance standards

Diameter 75 mm - 2500 mm
  customer-specific on request
Coating Barium sulfat (BaSO4)
Wavelengths BaSO4 300-2400 nm
  PTFE 200-2500 nm
  Gold 0,7 - 20 µm
Ports 1 (Standard)
Lamp ports 1 - 25
Accessories UControl control unit
  RMD sensors
  Port apertures

Examples of our integrating spheres as luminance & radiance standard

The example shows a luminance standard with a 50 mm output port and 300 mm diameter. Four halogen lamps (8 max) were used. The luminance is 12,000 cd/m². The homogeneity is over 99.5% over the entire surface. Material: Barium sulphate


The example shows a radiance standard with an output port of 1200 mm and a diameter of 2500 mm. 25 halogen lamps (1000 W each) were used, one of them with a motorised iris diaphragm. The luminance of the large integrating sphere is 76,000 cd/m². The homogeneity is over 98% on the surface to be realised. material: PTFE

Accessories for luminance and radiance standards  

  • Ucontrol - controls the lamps and aperture and can record measurement data from the sensors.
  • RMD sensors
  • Spectrometer
  • Port apertures
  • Lamps with manual or motorized aparture

The team of experts at Opsytec Dr. Gröbel GmbH assists customers in selecting the optimum sphere design for their specific applications. This ensures that each integrating sphere is perfectly matched to the individual measurement requirements.