The Polarimeter für bolometer Kameras (PolKa) was developed by the Bolometer Group at the Max-Planck-Institut für Radioastronomie (MPIfR) and mounted on the Atacama Pathfinder Experiment (APEX) telescope in October 2009.

PolKa is a fast reflection-type polarisation modulator that is used with LABOCA. The combination of PolKa + LABOCA makes the most powerful polarimeter for continuum emission in the world. Additionally, it’s the first ever of its kind in the southern hemisphere. The modulator of PolKa was designed and manufactured by the Fraunhofer Institute for Applied Optics and Precision Engineering in Germany.

PolKa has numerous applications, from the study of magnetic fields in molecular clouds in our galaxy to the study of the variability of the polarisation in the synchrotron emission from the jets of AGNs.

PolKa is an enhanced version of the polarimeter for bolometer cameras that was developed at MPIfR between 2000 and 2004. It was first tested at the Heinrich Hertz Telescope in 2001 at the IRAM MRT in 2004.

PolKa on APEX

This table lists the global capabilities of the instrument.

Location: Chajnantor
Telescope: APEX
Focus: Cassegrain
Type: Polarimeter
Wavelength coverage:

870 μm

Spatial resolution:

18.6 arcseconds

Spectral resolution:


First light date: 2009
Science goals:
  • Study of magnetic field in molecular clouds;
  • Study of variability of the polarization in the synchrotron emission form the jets of AGNs.
Images taken with the instrument: N/A
Images of the instrument: N/A
Press Releases with the instrument: N/A


  • ESO
  • MPIfR, Germany