There is described an optical radiation sensor device for detecting radiation in a radiation field. The device comprises a sensor element capable of detecting and responding to incident radiation from the radiation field and a radiation window interposed between the sensor element and the radiation field. The radiation window comprises a non-circular (preferably square) shaped radiation transparent opening. The optical radiation sensor device can be used in a so-called dynamic manner while mitigating or obviating the detection errors resulting from the use of a circular-shaped attenuating aperture and/or angular (even minor) misalignment of the sensor device with respect to the array of radiation sources when multiple such circular-shaped attenuating apertures are used.