Dish Surface Optimization System
Caltech Submillimeter Observatory
Melanie Leong
August 15, 2002

Dish Surface Optimization System Agenda
Primary Specifications
99 Channel Dish Surface Optimization System
Engineering Challenges
Major Milestones
Performance
Test Results
Efficiency with 692 Receiver
Efficiency with SHARCII
Future Plans

Dish Surface Optimization Sys Primary Specifications
Desired Performance Specifications
+/- 25 Micron Length Change for Most of Dish
Reduce RMS Surface Error from 25 Micron RMS to 15 Micron RMS
Improve Aperture Efficiency by a Factor of 2, Integration Time by a Factor of 4
+/- 50 Micron Length Change for Perimeter of Dish
3 Toothpick Controller/Driver Prototype Demonstrated that desired length changes can be achieved
99 Channel Dish Surface Optimization System Requested to Build ASAP

Dish Surface Optimization
System Diagram
DSOS Simplified Block Diagram for (1) Channel
Dish Surface Optimization Sys Toothpick Assembly
Dish Surface Optimization Sys Dish Wiring & Plumbing
Dish Surface Optimization System Racks
Dish Surface Optimization Sys 99 Channel Controller Unit
Dish Surface Optimization Sys 99 Channel Controller Unit (cont.)
Dish Surface Optimization Sys 25 Channel Driver Unit
Dish Surface Optimization Sys 25 Channel Driver Unit (cont.)
Dish Surface Optimization System Performance
Command Value to Micron Movement Verifies +/- 25 Micron Desired capability
Power Consumption
Power Draw At Start Up = 4kWatts
Quiescent Power Draw = 840 Watts
Added Weight to Dish - 268 lbs
Approximate Weight of System on 3rd Floor - 1,994 lbs

Dish Surface Optimization Sys
Length Change Capability
DSOS Test Results
Efficiency with 692 Rx
Efficiency Done Due to Lack of Planets
Determined From Past Holography Maps to Act on (14) Toothpicks out of (99)
14% Improvement of Object Temperature w/ 692 Rx
All Scans Showed An Improvement
Calculated Expected Improvement is 21% with all (99) Toothpicks Activated
Indication That The Dish Surface Optimization System is on itŐs way

Dish Surface Optimization Sys
14% Improvement With 692Rx
DSOS Test Results
Efficiency with SHARC II
Activated (19) Toothpicks.  Determined From Past Holography Maps
27% Improvement of Peak Signal Power From Uranus
All Cycles Showed an Increase in Signal Power When Dish Correction is Applied

DSOS with SHARCII
27% Improved Signal Power
Dish Surface Optimization System Future Plans
Goal is to Obtain a 100% Improvement at 350 Microns
High Resolution Holography Maps Need to be Made
Interpolation to Determine Command Values in 10 Degree Steps in Zenith Angle for all 99 Channels
Calibration of all 99 Toothpick Assemblies
Software Control to Speed up Ramp and Settling Time
Power On/Off Controller Unit