The barrel will hold the lenses and optics for DESI, which will map one-third of the night sky. To create an accurate map, the barrel’s pieces must be accurately assembled to within 20 micrometers. Dial Machine of Rockford, Illinois, manufactured the barrel steel components. Its many tons of steel work were machined to the incredible accuracy required. Photo: Reidar Hahn
This Fermilab team is currently assembling the barrel for the Dark Energy Spectroscopic Instrument, a project being led by Lawrence Berkeley National Laboratory. From left: Jorge Montes, Mike Roman, David Butler, Gaston Gutierrez, Giuseppe Gallo, Otto Alvarez. Photo: Reidar Hahn
The photo show the finished lens, undergoing verification testing of the surface roughness specification
“Philippe Godefroy (CEO of Winlight systems) inspecting the glass blanks for the DESI production spectrograph cameras. All of the blanks in both racks are for the DESI cameras.”
The ten, final DESI Spectrograph Blue channel diffraction gratings have been successfully verified for optical quality.
The diffracted wavefront transmitted across the full 14 cm aperture of one grating is shown in these data.
The data were taken at the LBNL Advanced Light Source optical measurement laboratory.
Corrector barrel in Coordinate Measuring Machine (CMM) room at Fermilab for gravity deflection measurements
The first, fully integrated DESI Spectrograph (known as the Engineering Model) is shown residing on it’s optical bench undergoing performance tuning and testing. The testing is being performed by the DESI Collaboration at Winlight SA, Pertuis, France. A light source feeds light into the spectrograph optical system, hidden under light covers and baffles ( black plates), and through the cameras (black cylinders) to be recorded.
Fiber Photometry Camera Image 4765, showing light from target stars emerging from three fibers while guiding the telescope using the DESI GFA