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IRIS Telescope Camera
Kimberly BottInstitute for AstronomyMentor: Klaus Hodapp
Home Institution: University of Hawaii at Hilo
2008 Center for Adaptive Optics Akamai Internship
Introduction• Infrared Imaging Survey
System (near IR)• Telescope fabrication in
Germany• Camera fabrication in
US • IRIS site: Cerro
Armazones Observatory in Chile
• Telescope Goals– Occultation– Variations in reflection
nebulae
• Camera Goals– Effective IR camera– Correct for spherical
aberrations
Infrared Camera• Cryostat interior to vacuum
– Why a cryostat?
• Three components– Designed mounting– Designed and fabricated
vacuum casing– Learned to fabricate on
cryostat piece– Goals
• Be lightweight, balanced and strong
• Allow extra volume for cryostat piece
Infrared Camera• Cryostat interior to vacuum
– Why a cryostat?
• Three components– Designed mounting– Designed and fabricated
vacuum casing– Learned to fabricate on
cryostat piece– Goals
• Be lightweight, balanced and strong
• Allow extra volume for cryostat piece
Infrared Camera• Cryostat interior to vacuum
– Why a cryostat?
• Three components– Designed mounting– Designed and fabricated
vacuum casing– Learned to fabricate on
cryostat piece– Goals
• Be lightweight, balanced and strong
• Allow extra volume for cryostat piece
Infrared Camera• Cryostat interior to vacuum
– Why a cryostat?
• Three components– Designed mounting– Designed and fabricated
vacuum casing– Learned to fabricate on
cryostat piece– Goals
• Be lightweight, balanced and strong
• Allow extra volume for cryostat piece
Testing the Camera’s Existing Cryostat
• Test vacuum• Inject liquid nitrogen
into cryostat – Monitored weight of
camera to determine holding time
– Improve holding time– Retest with new
pieces
Design of Mounting Piece
• Designed as strong connection between camera and telescope
Vacuum Casing Design
• AutoCAD drawing• Connection between
existing casing and large mounting piece
• Allowing for an effective vacuum– Smooth to reduce
dust/oil presence– Lower emissivity
Fabricating the Part
• Used lathe to aid other intern with small cryostat piece
• Began work on own part– Required improvising
due to unusual size and an octagonal end
Testing the Part
• Assembled• Achieved near
perfect vacuum
Filter Wheel Electronics
• 7 IR filters on large gear
• Driven by stepper motor
• Located with a Hall Effect Sensor
• Controlled through computer (program in C)
Electronics
• Replaced connections– Female electronics
to male– Female to the
stepper motor and the Hall Effect sensor
Electronics Testing and Results
• Tested connections with multimeter
• Tested ensemble, ran program to begin locating filters– Did not align– Fixed number of
teeth in C program– Still an issue finding
the magnet
Conclusions
Mounting piece: accurate design
Vacuum casing: effective vacuum which does hold
Filter wheel electronics: good connections but improper alignment not due to tooth number
Acknowledgements and Sources
• The Akamai Internship Program, funded by the Center for Adaptive Optics through its National Science Foundation Science and Technology Center grant (#AST-987683)
• Institute for Astronomy • Dr. Klaus Hodapp• Richard Shelton
• “The Infrared Imaging Survey (IRIS) System”, Hodapp et al.• “Cryostat Design and Construction at the IRTF”, Toomey et al.• http://uigi.com/nitrogen.html
Additional Links
• http://www.magnet.fsu.edu/education/tutorials/java/halleffect/index.html
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