LED-4xx - Luminous intensity measurement adapters for LEDs

For measuring luminous intensity [cd] of LEDs, Instrument Systems has developed a range of suitable measurement adapters. These can be differentiated by their useable spectral range (visible or UV), the required measurement geometry ILED-B and the intended application (laboratory or manufacturing).

LED-4xx - Luminous intensity measurement adapters for LEDs

The measurement adapters incorporate a diffuser with a precision aperture of 1 cm² to represent the light sensitive area of the detector. The entrance facet of a fiber bundle is positioned behind the diffuser and serves to couple the light into the spectrometer. This design is characterized by a high light throughput together with acceptable homogeneity of the detector area. The LED-4xx series of measurement adapters is therefore suitable for low light output LEDs as well as for fast production testing.  

For applications which require the highest accuracy, the LED 25 was developed for "Averaged LED Intensity" measurements according to CIE 127 recommendations. The LED 25 is based on an integrating sphere and features a perfectly homogeneous light sensitivity over the entire detector area, although with significant sacrifice of the light throughput.

The LED-4xx measurement adapters are compatible with all test sockets of the LED-5xx, -6xx, and -81x series. A reproducible and exact positioning of the LEDs is ensured by use of a clamping fixture. Special shortened versions are available for use in manufacturing environments (e.g. in combination with LED sorting machines.


  • CIE 127 compliant for luminous intensity or "Averaged LED Intensity"
  • available in configuration for ILED-B
  • high light throughput enables short acquisition times
  • clamping fixture ensures reproducible positioning of LED test sockets
  • suitable for all LED test sockets with 25 mm diameter (LED-5xx, LED-6xx, LED-81x)
  • connects via fiber bundle to all Instrument Systems spectrometers  

Overview of Instrument Systems LED measurement adapters:

ModelSpectral rangeMeasurement geometryFormat
Measurement adapter for lab applications (with LED test sockets)
LED25-430UV-VIS-IRCIE ILED-Bintegrating sphere
Short measurement adapter for production applications
LED-433-1 1)
LED-434-B-1 1)
LED-453VIS-IR0.01 sr at 50 mm separation
LED-439 2)
LED25-235 3)CIE ILED-Bintegrating sphere

1) Version with protective glass
2) LED-439 is an extension for use of the LED-43x und LED-45x adapters with the Instrument Systems LED test sockets
3) Adapter for LED 25 optical probe