State-of-the-art CME measurement

James F. Gilmore

doi:10.1117/12.218657

6 September 1995 State-of-the-art CME measurement

James F. Gilmore

Proceedings Volume 2542, Optomechanical and Precision Instrument Design; (1995) https://doi.org/10.1117/12.218657
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

The coefficient of moisture expansion (CME) of a material needs to be well known to accurately predict moisture induced dimensional changes and account for them is the design of large, stable optical benches. Historical methods for measuring CME are identified and discussed. The uncertainties associated with those earlier methods are due to using two different coupons to measure the length and weight change, or the interruption of the coupon environment to perform the measurements. The state-of-the-art CME apparatus described has eliminated these uncertainties by measuring the weight and length change simultaneously on one coupon. The patented design uses two opposing linear variable differential transformers to precisely measure the coupon length change while suspended from a Cahn precision balance to accurately measure the coupon weight change. The resulting determination of CME is accurate to better than +/- 10 ppm/% moisture. The apparatus is described in detail and the innovative design attributes that enable precise CME measurements to be made are discussed. Typical test data is also presented and discussed.

Citation Download Citation

James F. Gilmore "State-of-the-art CME measurement", Proc. SPIE 2542, Optomechanical and Precision Instrument Design, (6 September 1995); https://doi.org/10.1117/12.218657

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