Featured Research

from universities, journals, and other organizations

Expansion Of High Tech Materials

Date:
May 28, 2008
Source:
Physikalisch-Technische Bundesanstalt
Summary:
Industrial applications are ever more frequently demanding materials of highest thermal stability. A precision interferometer has been developed to exactly measure this property. With this instrument, the change in length can be determined with highest accuracy in an absolute measurement as a function of temperature, time and -- if necessary -- ambient pressure.

Thermal expansion coefficient (±) of a special glass with extremely low expansion. The progress of ± shown here derives from ± series of interferometrically measured lengths of a sample with parallel end surfaces as a function of temperature. In this example, there is a point of reversal at approximately 17.5 °C at which the thermal expansion disappears. Below this point, ± fall in temperature causes an expansion of the material. The figure (upper left) shows a typical topography of the interference phase, which includes the front surface of the body and ± wrung end plate. The averaged phase values within the rectangular areas on the end plate (left/right) and on the front surface of the body (middle), are the basis for the interferometrical length measurement.
Credit: Image courtesy of Physikalisch-Technische Bundesanstalt

 Industrial applications are ever more frequently demanding materials of highest thermal stability. A precision interferometer has been developed in the Physikalisch-Technische Bundesanstalt (PTB) to exactly measure this property. With this instrument, the change in length can be determined with highest accuracy in an absolute measurement as a function of temperature, time and - if necessary - ambient pressure.

Related Articles


Thermally stable materials play an important role in dimensional metrology and in precision manufacturing. The currently highest requirements on the thermal stability of critical components are made in EUV lithography of reflection masks and mirrors. These are, therefore, based on substrates made of high tech glass/ceramics which are to exhibit a very low thermal expansion coefficient (α < 1 · 10−8 · K−1).

For the precise characterization of gauge-blockshaped measuring objects made of high tech materials, a precision interferometer was developed with the aim of measuring samples of up to 400 mm length with uncertainties in the sub-nanometer range. From such exact measurements of length, it is possible to calculate the thermal expansion coefficient as a function of the temperature with uncertainties of up to 2 · 10−10 · K−1. Furthermore, it is possible to get quantitative statements regarding the homogeneity of the thermal expansion, compressibility, length relaxations and also the long-term stability of samples.

Length measurements with sub-nm uncertainties demand, besides the application of frequencystabilized lasers, the consideration of influences whose uncertainty contributions are difficult to minimize. For this purpose, various methods have been developed in the PTB in the last few years and these have been integrated into the measuring process. A new autocollimation process is cited as an example and this ensures that the lightwaves reach the surfaces of the measuring objects exactly perpendicularly.

The so-called cosine error is hereby lowered to under 10−11 · L . Furthermore during the electronic evaluation of the interference pattern, the exact assignment of the sample position to the camera pixel coordinates is considered. This is particularly important when it comes to measuring objects whose end faces are non-parallel and when the influence of small temperature-induced changes of the lateral sample position can be corrected. By taking the temperature-related influence of the deflection of the end plate wrung to the back into consideration, the precision could be increased further. When taking thermal expansion measurements on typical samples, length measurement uncertainties of 0.25 nm are now achieved.

In a recently completed international comparison measurement, the leading position of the PTB in the determination of thermal expansion coefficients was confirmed. The new possibilities for the precise characterization of high tech materials are already being used intensively by companies working in the fields of optics and precision manufacturing.


Story Source:

The above story is based on materials provided by Physikalisch-Technische Bundesanstalt. Note: Materials may be edited for content and length.


Cite This Page:

Physikalisch-Technische Bundesanstalt. "Expansion Of High Tech Materials." ScienceDaily. ScienceDaily, 28 May 2008. <www.sciencedaily.com/releases/2008/05/080528095653.htm>.
Physikalisch-Technische Bundesanstalt. (2008, May 28). Expansion Of High Tech Materials. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2008/05/080528095653.htm
Physikalisch-Technische Bundesanstalt. "Expansion Of High Tech Materials." ScienceDaily. www.sciencedaily.com/releases/2008/05/080528095653.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) — The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) — Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Who Will Failed Nuclear Talks Hurt Most?

Who Will Failed Nuclear Talks Hurt Most?

Reuters - Business Video Online (Nov. 25, 2014) — With no immediate prospect of sanctions relief for Iran, and no solid progress in negotiations with the West over the country's nuclear programme, Ciara Lee asks why talks have still not produced results and what a resolution would mean for both parties. Video provided by Reuters
Powered by NewsLook.com
Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Reuters - Innovations Video Online (Nov. 25, 2014) — A virtual flying enthusiast converts parts of a written-off Airbus aircraft into a working flight simulator in his northern Slovenian home. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins