More Zemax screenshots of the optical setup of the NIKA prototype installed since June 2012 at its final permanent position at the 30m telescope. S. Leclercq, Oct 2013 View from the back (of the receiver cabin) View from profile (elevation axis) View from above (roof) NIKA, M6, M5, M4, M3NIKA, M5, M4, M6, M3NIKA, M6, M4, M5, M3

Arrays, dichroic, aperture stop (cold pupil), field stop 100mK lenses, 4K lens, 300K lens (& window), (warm) pupil

Impact of a grid of rays from various fields on the image plane (= arrays); the FOV (circle) = 2.8 arcmin diameter. Spot diagram of the various fields; the colored dots are the impacts on the image of the rays traced through all the optics and stops, their repartition show the aberration spot, which can be compared to the diffraction spot of the 1mm wavelengths represented by the 1 st Airy dark ring (the elliptic shape is due to pupil aberration). The image is diffraction limited when the aberration spot is smaller than the Airy ring; the Strehl ratio gives a quantification of this image quality, its worse value on the image plane is 95% (while the diffraction limit is 80%). Grid distortion: the crosses show the position on the image plane of the chief rays of from a regular grid of fields incident to the telescope (the regular grid drawn represent the expected position if the system created no distortion).

Huygens Point Spread Functions (beams shape) in false color and logarithmic scale for the central filed and central wavelength (top left), central field and multi-wavelengths covering the 1mm band (top center), and fields at 4 corners of the 2.8’ FOV and multi- wavelengths (all other images). The green cross is due to the tetrapod holding the secondary mirror of the telescope. Huygens PSF of the central field for the central wavelength and multi-wavelengths on a more extended region and down to a deeper level of the log scale. There’s ~4 KIDs in the red dot, the size of the array diameter (2.8’) is 40 mm so about half the size of the square presented here (the dark circle gives an approximate representation of the KIDs array contour).