All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient (dn/dT) measurements
Abstract
This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity (Λ) and thermo-optic coefficient (dn/dT) of materials that are absorbing at λ= 10.6 μm and are transparent to semi-transparent at λ= 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50:50 split pump beam from a CO2 laser (10.6 μm). The technique and analysis methods are validated with measurements of 10 different optical materials having Λ and dn/dT properties ranging between 0.7 W/m K ≲Λ≲ 33.5 W/m K and −12 × 10−6 K−1 ≲dn/dT≲ 14 × 10−6 K−1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 03, 2016
- Source ID
- 10.1063/1.4948429
Entities
People
- Armando Arends
- Augustine M. Urbas
- Shawn A. Putnam
- Steven B. Fairchild
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- University of Central Florida