Transmission and reflection


The measurement setup for the determination of transmittance and reflectance of materials was built within the framework of the first IWT-HOBU project ‘Optical characterization of solar cell’ which ran in the light & lighting laboratory from 1997 until 1999.

The emission of a halogen lamp is sent through a filter wheel (to reduce stray light and avoid harmonic distortion) and a monochromator to allow for spectral measurements. Next, the light beam is split into two separate beams with a bifurcated optical fiber which transport the light to the entrance ports of the integrating sphere. This allows the simultaneous measurement of sample and reference (calibrated standard or open port) according to the double beam configuration.


  • Determination of diffuse and directional reflection and transmission
  • Determination of transflection (with one measurement)
  • Reflection or transflection in function of the angle of incidence of the incident irradiation (using a central mount sample holder)
  • The ideal specimen size is approximately 3 by 3 cm

Wavelength range

  • Photomultiplier: 350 – 800 nm
  • Si-detector: 420 – 1100 nm
  • InGaAs-detector: 800 – 1400 nm

Calibrated reference samples

  • Labsphere 30% reflection standard (NPL-calibrated-DV01)
  • Labsphere 99% reflection standard: SRS-99-010 Top
  • Sensor Systems 99% reflection standard: WS-2 (NPL-calibrated-DU01)
Complete setup for spectral transmittance and reflectance measurements
Detail of the integrating sphere
Schematic representation of the "double beam" configuration