Herschel M1/M2 Distance Measurements
27 May 2008On Friday, 16 May, M1/M2 distance measurements of the Herschel telescope were performed. These measurements are carried out in order to verify the optomechanical stability of the telescope. They are performed before and after significant testing (mechanical and environmental), transport and handling activities of the telescope.
In this case, the measurements were performed following the integration of the telescope with the spacecraft in mid-April. The measurements were made using a high precision laser tracker device to determine the distance between the primary and secondary mirrors (M1 and M2).
The optical measurements relate to knowledge of the telescope alignment and performance as measured while it was being manufactured. They are carried out in order to ensure that the integration process did not introduce any distortions.
The blue wiring visible in these images is a cable harness connecting the secondary mirror and its supporting structure (hexapod) to a set of motion sensors (accelerometers) that will be used during the upcoming vibration testing of the spacecraft.
Later this year the telescope's optomechanical stability will be checked again following completion of the vibration and thermal vacuum testing of the satellite at the ESTEC test facilities.