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