System integration is the main step in which all components and subsystems can be assembled together to make an instrument. In general our department take the largest responsibility at this stage. Cryogenic instrument must be tuned to reach good vacuum and temperature levels. It consists also in making the optical alignment which is always a critical step in the integration phase. Typical instruments contain several tens of optical components that must be aligned accurately according to design specifications. Alignment quality criteria are in general wavefront aberrations, image stability. They are controlled with interferometers, detectors and ccd... For cryogenic instruments, the task is even more difficult since alignment is done at warm temperature whereas the verifications must be done at cryogenic temperatures, leading to long iterations in which the instrument has to be pumped, cooled down, warmed up again. In parallel to this, electronic and software departments must work on instrument control. All functions, CCDs, detectors must be driven through an instrument control software, via a local control unit electronics.
Assembly, Integration and Testing