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DIMENSIONAL STABILITY INVESTIGATION OF LOW CTE MATERIALS AT TEMPERATURES FROM 140 K TO 250 K USING A HETERODYNE INTERFEROMETER

Spannagel, Ruven and Hamann, Ines and Sanjuan, Jose and Guzman, Felipe and Braxmaier, Claus (2017) DIMENSIONAL STABILITY INVESTIGATION OF LOW CTE MATERIALS AT TEMPERATURES FROM 140 K TO 250 K USING A HETERODYNE INTERFEROMETER. In: Proceedings of the International Astronautical Congress, IAC. 68th International Astronautical Congress 2017, 25.-29.09.2017, Australien, Adelaide.

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Abstract

Light weight materials with excellent dimensional stability are increasingly needed in space based applications such as telescopes, optical benches, and optical resonators. Glass-ceramics and composite materials can be tuned to reach very low coe�cient of thermal expansion (CTE) at certain temperatures, including room temperature and cryogenics, where a growing number of instruments in scienfic and earth observation space missions are operated. Very accurate setups are needed to determine the CTE of such materials. With our laser-interferometric dilatometer setup we are able to measure CTEs of a large variety of materials in the temperature range of 140 K to 250 K. Special mirror mounts with a thermally compensating design enable measurements of the expansion of cylindrical tube-shaped samples using a heterodyne interferometer with demonstrated noise levels in the order of 10 pm/pHz. The temperature variation of the sample is obtained by a two stage controlled heating/cooling setup where a pulse tube cooler and electric heaters apply small amplitude temperature signals to cool/heat the sample radiatively in order to reach a homogeneous temperature over the whole sample. A carbon �ber reinforced polymer (CFRP) sample was selected to run CTE measurements, achieving results in the 10^8 K^1 range including all known uncertainties. The limitations of our setup have been identi�ed and the largest uncertainty contribution has been determined to be tilt-to-length coupling of the sample due to temperature variations. Several improvements are currently underway to minimize our uncertainty budget. New results with the enhanced setup will be presented

Item URL in elib:https://elib.dlr.de/118073/
Document Type:Conference or Workshop Item (Poster)
Title:DIMENSIONAL STABILITY INVESTIGATION OF LOW CTE MATERIALS AT TEMPERATURES FROM 140 K TO 250 K USING A HETERODYNE INTERFEROMETER
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Spannagel, RuvenDLR-RY, BremenUNSPECIFIED
Hamann, InesDLR-RYUNSPECIFIED
Sanjuan, JoseDLR-RYUNSPECIFIED
Guzman, FelipeDLR BremenUNSPECIFIED
Braxmaier, Clausclaus.braxmaier (at) dlr.deUNSPECIFIED
Date:2017
Journal or Publication Title:Proceedings of the International Astronautical Congress, IAC
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:No
Status:Published
Keywords:Temperature, Interferometer, CTE, Dilatometer
Event Title:68th International Astronautical Congress 2017
Event Location:Australien, Adelaide
Event Type:international Conference
Event Dates:25.-29.09.2017
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Technik für Raumfahrtsysteme
DLR - Research theme (Project):R - Systems Engineering Optische Systeme
Location: Bremen
Institutes and Institutions:Institute of Space Systems > Systems Enabling Technologies
Deposited By: Hüls, Simone
Deposited On:11 Jan 2018 10:21
Last Modified:15 Mar 2018 09:22

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