Stepper motors at LHe temperatures in astronomical mid-infrared instrumentation

David S. Theil; Robert E. Stencel; Dimitri I. Klebe; Dale Flaming; Jack Belgum

doi:10.1117/12.363817

28 September 1999 Stepper motors at LHe temperatures in astronomical mid-infrared instrumentation

David S. Theil, Robert E. Stencel, Dimitri I. Klebe, Dale Flaming, Jack Belgum

Proceedings Volume 3786, Optomechanical Engineering and Vibration Control; (1999) https://doi.org/10.1117/12.363817
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1999, Denver, CO, United States

Abstract

The University of Denver is now completing construction of a mid-infrared imaging polarimeter dubbed TNTCAM Mark II. The instrument will be the only one of its kind capable of attaining polarimetric accuracy of 0.2 % across the 5 -- 25 micron spectral interval. This sensitivity is only attainable by cooling the transmissive polarizing optics to liquid helium (LHe) temperatures. A major technical challenge in the design of this instrument has been finding a way to modulate the polarization signature of the incoming beam at a rate sufficient to combat the degrading effects of the atmosphere. Our group has chosen to quickly rotate a half-waveplate situated on the cold (i.e. 4 degrees Kelvin) work-surface. The waveplate is rotated between two fixed positions separated by 45 degrees at a rate of 1 Hz to obtain one of the two Stoke's parameters required to measure linear polarization. The waveplate is then offset by 22.5 degrees and then rotated again at 1 Hz between two positions separated by 45 degrees to obtain the other Stoke's parameter. In addition to rotating the waveplate, the waveplate itself must be moved out of the beam during normal imaging applications. The camera can contribute to the understanding of YSOs and evolved stars, obtaining high resolution mid-IR observations of dusty environments immediately surrounding these objects. In imaging mode mosaics of extended objects can be made in 2'x2' sub-fields. In polarimetry mode, B-fields in YSOs can be probed by dust emission from hot cores, incidentally constraining grain alignment scenarios in young stellar environments. In this paper we present the design and the results of our moving optical componenets susbsytem. Five cryo-stepper motors drive these mechanisms. This instrument is being developed under NSF grant AST-9724506 and is slated for community access in January 2000.

Citation Download Citation

David S. Theil, Robert E. Stencel, Dimitri I. Klebe, Dale Flaming, and Jack Belgum "Stepper motors at LHe temperatures in astronomical mid-infrared instrumentation", Proc. SPIE 3786, Optomechanical Engineering and Vibration Control, (28 September 1999); https://doi.org/10.1117/12.363817

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
8 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Sensors

Polarimetry

Stars

Wave plates

Cryogenics

Helium

Magnetic sensors

Show All Keywords

Keywords/Phrases

Search In:

Publication Years