The image above shows the now assembled turret that will hold the polarizing beam splitters. It rotates around it central vertical axis, as seen in the video below. Additional motors on the sides will allow us to exchange the two beams with each other, by rotating the optical elements. The turret is less than 15 cm in diameter and will soon be transported from Uppsala to Garching for more testing and integration.
This short video shows Alexis Lavail demonstrating the turret rotation, together with a short explanation by Nikolai Piskunov:
“Slit decomposition” is the algorithm that we use in the new data-reduction system to extract 1D-spectra from the detector images. This works by approximating a cut-out from a spectral order (top-left panel) by two one-dimensional vectors (black lines), one being the spectrum (middle panel), the other the slit illumination (right panel). From these two one can reconstruct a 2D-model, which is shown in the lower left panel. The animation shows how we step in overlapping chunks along the spectral order. The red dots are the individual pixel values from the input image, collapsed along the respective direction.
This week we held another consortium meeting at ESO headquarters; and took a new group photo in the integration hall. In the back to the right is the open cryostat, the elevated large black box in the middle holds the new warm optics and calibration unit.