— From David Le Mignant (LAM)
We talked about the cooling verification of the cryostat body of the Visible Camera Unit for the Spectrograph at Johns Hopkins University (USA).
After that process, the cryostat body was shipped to Laboratoire d’Astrophysique de Marseille (LAM) in France, where other parts are also delivered from the collaborators and a complete Visible Camera Unit for the Spectrograph is assembled: The camera optics are integrated inside the cryostat body together with the focus mechanism, thermal sensors and a mechanical dummy detector, and then the validation process continues.
(Integrating the camera unit 1)
(Integrating the camera unit 2)
(Integrating the camera unit 3)
A critical step for the PFS visible camera is to verify that the cryo-cooler and the general thermo-mechanical design allow to operate the detector at a 160 K temperature. Yet, some parts of the Visible Camera Unit, like the Mangin mirror and the front ring, need to remain at room temperature. Additional temperature sensors have been inserted for the thermal validation to get a full mapping of the temperature distribution in the camera unit, particularly around the detector box. We will also operate the focus mechanism and simulate the heat of the detector to validate the thermal performance of the Visible Camera Unit.
Nominally, this thermal validation verification step is only performed once for the first camera.
(Visible Camera Unit under the thermal validation)