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Thermal Conductivity and CTE Measurements by Displacement Thermo-Optic Phase Spectroscopy (D‑TOPS)

Simultaneous determination of thermal conductivity and linear coefficient of thermal expansion of thin layers and bulk samples with spatial resolution down to a few microns.

Overview of the Method

Displacement thermo-optic phase spectroscopy (D-TOPS) measures thermal conductivity and the coefficient of thermal expansion (CTE) simultaneously. The method provides quantitative thermophysical properties on microscale sample volumes without requiring large sample sizes or mechanical loading.

The sample surface is heated with an intensity-modulated pump optical beam, producing localized thermal expansion and periodic surface displacement. A probe beam reflected from the displacement field undergoes is detected synchronously by a position-sensitive-detector and lock-in amplifier. The thermal conductivity and coefficient of thermal expansion are determined by analyzing the amplitude and phase of the frequency-dependent response from 20 Hz to 200 kHz.

Technical Specifications

Measured Parameters

Thermal conductivity (κ) and coefficient of thermal expansion (CTE, α).

Applicable Materials

Polymers, semiconductors, dielectrics, and metals.

Sample Thickness Range

Specimens as thin as 0.3 µm up to bulk.

Metrology Strengths

Less sensitive to surface roughness than thermoreflectance methods and provides high signal-to-noise ratio for rapid spatial mapping of properties

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