| Evaluation of the ALMA Prototype Antennas |
| Jeff Mangum (NRAO) | |
| For the Antenna Evaluation Group (AEG) |
| The ATF |
| The AEG |
| Jeff Mangum (NRAO) | |
| Jaap Baars (ESO/MPIfR) | |
| Albert Greve (IRAM) | |
| Robert Lucas (IRAM) | |
| Ralph Snel (Lund University) | |
| Pat Wallace (RAL) |
| ATF Chronology |
| 1999 June: D. Emerson and Mangum develop first prototype antenna test plan | |
| 2001 May 14: AEG is born | |
| 2002 March: AEG and Systems IPT begins ATF infrastructure installation | |
| 2002 November: VertexRSI prototype antenna able to position in (Az,El) | |
| 2003 January 13: VertexRSI prototype antenna first radiometric measurement (1mm and 3mm total power measurement of the Moon) | |
| 2003 March: VertexRSI prototype antenna provisional acceptance | |
| 2003 April-July: VertexRSI prototype antenna holographic measurements | |
| 2003 October: VertexRSI prototype antenna acceptance | |
| 2003 November: VertexRSI prototype antenna first astronomical radiometric image (Saturn at 3mm) | |
| 2004 January: AEC prototype antenna able to position in (Az,El) | |
| 2004 January-February: AEC prototype antenna holographic measurements | |
| 2004 May: AEC prototype antenna first astronomical radiometric image | |
| 2004 May 28: AEG Executive Summary of the ALMA Prototype Antenna Evaluation delivered | |
| 2004 December 1: Final AEG prototype antenna evaluation reports delivered |
| VertexRSI and AEC Prototype Antennas |
| Major Antenna Performance Specifications |
| Near-Field Radiometric Holography System |
| Transmitter: | ||
| Photonically-generated signal | ||
| 50m high tower located 310m from antenna | ||
| Receiver: | ||
| 79/104 GHz dual-receiver system | ||
| 10 mm spec; 5 mm goal | ||
| Gildas data analysis (Lucas) | ||
| Evaluation Frontend System |
| Optical Pointing Telescope |
| NRAO Design | |
| 4-inch Refractor | |
| Rolled-Invar Tube | |
| COTS CCD/Frame Grabber |
| Accelerometer System |
| 10 Endevco Model 86 Seismic Accelerometers | |
| 2/3 Axis Configuration | |
| Sensitivity over 0.1 to 30 Hz (10 to 0.03 sec) with accuracy several mm to 10 nm | |
| Extended to 0.001 Hz (15 minutes) using wind power spectrum extrapolation | |
| Coupled with Sonic Anemometer Measurements |
| API5D Measurements |
| Laser Interferometer | ||
| Measures 5D Displacement | ||
| Accuracy: | ||
| Device: 0.2 mm/m | ||
| Enclosed System: < 1 mm | ||
| Exposed System: Few mm | ||
| Reflector Surface Accuracy |
| Techniques and Systems Used: | |
| Near-Field Radiometric Holography | |
| Accelerometer System | |
| Radiometric Efficiency Measurements | |
| Temperature Sensor System |
| Surface Setting |
| Near-Field Radiometric Holography Results |
| Near-Field Radiometric Holography Results (Cont.) |
| Radiometric Measurements of Mercury |
| VertexRSI (left) | |
| qMercury = 5.1 arcsec | |
| 265 GHz | |
| Solar Separation 16¡ |
| Reflector Surface Accuracy Performance Summary |
| Pointing |
| Techniques and Systems Used: | |
| Optical Pointing Telescope (OPT) | |
| 1 and 3 mm Radiometry | |
| Accelerometer System |
| All-Sky Optical Pointing Results |
| Accelerometer Measurements of Offset Pointing |
| 4 BUS rim accelerometers used to derive BUS pointing | |
| Red: SOW wind, Green: Chajnantor wind, Blue: antenna wake turbulence |
| Pointing Performance Summary |
| Fast Switching |
| Techniques and Systems Used | |
| Radiometer | |
| Optical Pointing Telescope | |
| Accelerometer System |
| Radiometric Fast Switching Performance |
| Optical Fast Switching Performance |
| Fast Switching Performance Summary |
| Path Length Stability |
| Systems and Techniques Used: | |
| Automated Precision Incorporated (API) 5D Laser Interferometer | |
| Accelerometer System |
| API5D Path Length Stability Measurement Results |
| Path Length Stability Performance Summary |
| ALMA Prototype Antenna Performance Summary |
| Coming Attractions |
| Ralph Snel (Lund University): Accelerometer Investigations of the ALMA Prototype Antennas | |
| Jeff Mangum (NRAO): Near-Field Radio Holography of the ALMA Prototype Antennas | |
| Albert Greve (IRAM): Mechanical Measurements of the ALMA Prototype Antennas | |
| Jeff Mangum (NRAO): Pointing, Tracking, and Fast Switching Performance of the ALMA Prototype Antennas |
| Acknowledgements |
| The Indispensable Four | |
| Nicholas Emerson | |
| Robert Lucas | |
| Jack Meadows | |
| Fritz Stauffer |
| Nicholas Emerson |
| Robert Lucas |
| Jack Meadows |
| Fritz Stauffer |
| The ATF Backbone |
| Christian Holmstedt (NRAO) | |
| Andrea Vaccari (NRAO) | |
| Greg Chavez (NRAO) | |
| Mike LeBlanc (NRAO) | |
| Jon Spargo (NRAO) | |
| Brian Glendenning (NRAO) | |
| Ralph Marson (NRAO) | |
| Ken Ramey (NRAO) | |
| Mark Holdaway (NRAO) | |
| Pepe Lopez-Perez (OAN) | |
| Angel Otarola (ESO) | |
| Patty Lindsey (NRAO) | |
| Jinquan Cheng (NRAO) | |
| Marc Rafal (NRAO) | |
| VLA Mechanical Shop |