Measurement equipment development and construction

Trap detectors

The Research and Development Division at Metrosert designs and builds multi-element optical power responsivity detectors known as trap detectors. We have experience in constructing 3-, 4-, 6- and 10-element trap detectors, both in reflectance and transmittance configuration.
All traps are based on high-quality photodiodes of either 10×10 mm2 or 18×18 mm2 in photodiode active area. The output signal of the detector is photocurrent. The photodetector housing and electrical connectors (type BNC or Lemo) can be customized upon request. Also, temperature-stabilised filter radiometers utilising trap detectors can be manufactured.

Kolme-elemendiline fotodetektor koos kaitsekorgiga
Three-element detector with protective cap

Beam path in 3-element trap detector

The remarkable features of trap detectors:

  • low reflection-loss
  • large active area
  • good spatial responsivity
  • predictable reflectance/transmittance over visible wavelength range

Each trap will be spatially characterized (uniformity of responsivity over
active area) prior to shipping.

For enquiries, please contact:

  • Toomas Kübarsepp,
  • Meelis-Mait Sildoja,





Relevant publications:

  • Toomas Kübarsepp, Petri Kärhä, and Erkki Ikonen, “Characterization of a polarization-independent transmission trap detector,” Appl. Opt. 36, 2807-2812 (1997)
  • Toomas Kübarsepp and Malcolm White, “Ten-element photodetector for optical power and attenuation measurements,” Appl. Opt. 49, 3774-3779 (2010)
  • Toomas Kübarsepp, Atte Haapalinna, Petri Kärhä, and Erkki Ikonen, “Nonlinearity measurements of silicon photodetectors,” Appl. Opt. 37, 2716-2722 (1998)