1. Error Budget Calculation
OFFRE XXXX
Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas
Error Budget Calculation
PM# September 2006

2. Pointing Error - Approach
OFFRE XXXX
Error Budget Calculation without metrology correction: Pointing Error
Pointing Error - Approach
Geometrical ray tracing, by means of CODE-V, is used to calculate pointing error.
Diffraction is taken into account to determinate energy centroid.
The displacements of the nodes representing the optical elements of the antenna and the rotations of the frames associated to them are determined by thermo-elastic analysis.
Displacements and rotations are applied in the CODEV model and results are shown.
The optical model treats the main reflector as a rigid body, but its translations/rotations introduced in CODE-V are derived from the parabolic best fit of the deformed surface of the paraboloid computed with FEM analysis (Levy’s procedure).

3. Pointing Error – Wind component
OFFRE XXXX
Error Budget Calculation without metrology correction: Pointing Error
Pointing Error – Wind component

4. Pointing Error – Weighted wind component
OFFRE XXXX
Error Budget Calculation without metrology correction: Pointing Error
Pointing Error – Weighted wind component
RMS errors are compared with EIE’s output

5. Error Budget Calculation without metrology correction: Pointing Error
OFFRE XXXX
Error Budget Calculation without metrology correction: Pointing Error
Ray Tracing approach – code V
Analytical approach- Ruze equations
RMS errors are compared with EIE’s output

6. The above RMS errors are compare with those obtained by EIE
OFFRE XXXX
Error Budget Calculation without metrology correction: Pointing Error
The above RMS errors are compare with those obtained by EIE
Differences between EIE and AAS-I are < 1% (0.17%!)
Complete convergence is being checked for all the remaining budgets
Some details of the FEM model require fine adjustments