The POLARBEAR experiment is mounted on the Huan Tran Telescope (HTT) at the James Ax Observatory in the Chajnantor Science Reserve.

The instrument was first installed at the Combined Array for Research in Millimeter-wave Astronomy site near Westgard Pass in California (USA) for an engineering run in 2010.

[5] These measurements focused on arcminute scale fluctuations likely sourced by gravitational lensing by intervening large-scale structure.

POLARBEAR's published measurements focused on a small but clean patch of the sky where galactic foregrounds should be subdominant to gravitational lensing B-modes.

The POLARBEAR team was able to report that the measured B-mode polarization was of cosmic origin at a 97.2% confidence level by focusing their observing time on this small patch where they are highly sensitive to arcminute anisotropies.