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Article
Microwave-Dimensional Measurements of Cylindrical Resonators for Primary Acoustic Thermometry
Acoustic gas thermometry relies on the fundamental relationship between the speed of sound in a monatomic gas and its thermodynamic temperature. The speed of sound is calculated from the resonance frequencies ...
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Article
A Novel Comparative Photothermal Method for Measuring Thermal Diffusivity
A novel comparative method has been developed at the National Physical Laboratory (NPL) to measure the thermal diffusivity of semi-infinite samples without a priori knowledge of the boundary conditions. It is bas...
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Article
Measurement of the Thermal Diffusivity of Solids with an Improved Accuracy
A photothermal radiometry technique is being developed at the NPL with the goal of improving the accuracy of thermal diffusivity measurements. The principle is to perform a laser-induced thermal experiment whi...
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Article
A temperature-dependent dispersion equation for congruently grown lithium niobate
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Chapter and Conference Paper
Progress with a Determination of the Speed of Light
The scheme for measuring the CO2 laser frequency (shown in the Introduction) consists of three separate frequency-mixing experiments using two lower-frequency lasers as transfer oscillators. If an accurate measur...
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Chapter and Conference Paper
Progress with a Determination of the Speed of Light
Until recently the direct measurement of frequencies in the infra-red spectral region has not been possible because of the lack of suitable detectors and mixers with response times of the order of 10−13 to 10−14 ...