IMACS Engineering Run, Sat Sept 30 - Wed Oct 4
- IMACS Engineering Run, Sat Sept 30 - Wed Oct 4
- Tasks
- Personnel and Observatory Support Required
- Report
Tasks
Clean Field Lens
- Unmount Field Lens and prepare for cleaning (remove from lens ring).
- Measure throughput, both pre and post wash.
- Reassemble and reinstall Field Lens.
Measure Collimator Throughput
- Remove Collimator and disassemble for throughtput measurements.
- Measure throughput and wash/clean lenses if necessary/possible.
- Reassemble and reinstall Collimator.
Install modified SMS components
- Install new Delrin groove plate.
- Assemble masks with modified wings.
Investigate Shutter Failures
- Remove and disassemble shutters for full inspection.
- Note problems and any modifications necessary.
Miscellaneous Maintenance and Other Work
- Continued light leak investigation - more pinhole camera images.
- Continued investigation of the SH image motion.
- Examine Renishaw encoder tape on off axis guiders to investigate reported problems including continuity issue.
Personnel and Observatory Support Required
SBS
- Tyson Hare; arrives Sept 29, leaves Oct 5.
- Alan Dressler
LCO
- Franks Perez
- Dave Osip
- Instrument Specialist
- Machinist
Report
Clean Field Lens
- The C01/C02 baffle was removed. The field lens tooling was installed and the dome crane was employed to lift the field lens assembly out of the instrument and lowered to the dome floor.
- The lens was removed from its cell and washed using an acetone flush bath while suspended in its tooling.
- The throughput was measured to be approximately 98.5% before and after the wash.
- The field lens was succesfully inserted into the lens cell and reinstalled on the instrument.
Measure Collimator Throughput
- Removed the collimator from the instrument and lowered to a cart on the dome floor using the dome crane.
- Multiple throughput measurement were taken and reported below. A dramatic increase in throughput was observed after washing C02 and proved effective in increasing overall throughput in the collimator to 87.7%.
| Type | Element | Pre-Wash (% loss) | Post-Wash (% loss) |
| Singlets | C02 | 14.5 | 4.13 |
| - | C03 | 2.92 | 2.88 |
| Doublet | C04/C05 | 2.625 | n/a |
| - | w/C03 | n/a | 7.97 |
| Collimator | - | - | 13.3 |
Install modified SMS components
- Partially disassembled the SMS cassette to install the modified Delrin groove block. This block had grooves machined less deep (0.6 mm) with lead-ins in an effort to constrain mask freeplay (when in the cassette), improve performance (when moving between sationary positions) and increase reliability.
- Preliminary testing indicate that the modification are an improvement to the design. The SMS was operated through multiple cycles in various orientations and the performance was good.
- This take was primarily undertaken by M. Navarette and J. Bravo, with direction, instruction and discussion.
Investigate Shutter Failures
- Investigation of recent shutter failures resulted in discovery that the right f/2 shutter failed to initialize in certain orientations.
- When moved manually the motion seemed uncharacteristically stiff or sticky, beyond the normal 'bump' inherient in the magnet design. Apparently vacuum grease was used to lubricate the shutter motors. This is generally a bad idea as vacuum grerase is thick and sticky.
- The shutters were removed from the instrument for cleaning and further inspection. Normal (insiggnificant) wear was visible. The motor sliders were cleaned and the shutters were reassembled and reinstalled.
- Shutter design and alignment procedures were discussed and demonstrated with many of the mountain technical staff, including specialists and technicins. They were also actively involved in these procedures, doing much of the work with supervision.
- After reinstallation the shutters seemed to perform as expected, however similar initialization problems presisted.
- Further investigation revealed potential problems with the cables and/or bulkhead connections. Since one set of cables seemed to be okay, it was decided to use the good set for both camera shutters until new cables can be provided.
Miscellaneous Maintenance and Other Work
- Continued light leak investigation was attempted, however the new pinhole aperture adapture placed images too far out of the field. Further, the new 20um pinholes didn't yeild quality images. This may be due to the fact that 20um is too small for a pinhole not located at focus.
- Installed new baffles on the LDP and 150l/mm grism
General Notes
- After discussion and examination of image data provided by D. Osip, it was decided to postpone mechanical flexure measurements of the SHGC until further investigation of the data could be completed. Also, it was decided that D. Osip would attempt to mount an LED at the focus of the SH barrel an image while rotating in an attempt to eliminate moving optics as a contributor to the spot motion problem.
- Required Parts
- new shutter cables
- redesigned pinhole aperture with 50um pinholes
- design LDP shroud
- Future Work
- further light leak investigation
- install new dewar guide pins
- modify lower slit mask wing to remove (round-off) knife edge at latch groove (returning edge)
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