Photothermal conversion surface measurements using photoacoustic and photothermal spectroscopies
Photoacoustic and photothermal spectroscopic techniques have recently been under development in a number of laboratories. When applied to solar materials studies these techniques have the potential of providing a more direct measurement of photothermal conversion efficiency than conventional reflection or transmission measurements. Measurements are made by modulating the intensity of an incident light beam which causes a temperature oscillation in the irradiated material under study with the oscillation amplitude proportional to the absorbed and subsequently thermalized light energy. In the photoacoustic method the oscillation amplitude is measured by a transducer which detects an acoustical signal driven by the temperature oscillation. A thermal transducer is used as the detector in the photothermal technique. Spectral or integrated measurements are made using a monochromatic or broadband source with no correction needed for the spectral dependence of a detector since the signal is generated by the interaction of light with the sample rather than with a detector. This allows spectrally integrated surface absorptivities to be measured directly, without integration of data, using a solar simulator, natural sunlight, or a blackbody source, with the latter operated at a temperature of interest for IR emissivity studies. Calibration methods currently being developed include standard surfaces and Joule heating based on electrical standards. Experimental set-ups are described.
- Research Organization:
- Ames Lab., Ames, IA (United States)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 6113731
- Report Number(s):
- IS-M-202; CONF-780550-10
- Resource Relation:
- Conference: Seminar on testing solar energy materials and systems, Washington, DC, USA, 22 May 1978
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SOLAR ABSORBERS
ABSORPTIVITY
REFLECTIVITY
ACOUSTIC MEASUREMENTS
ACOUSTICS
EFFICIENCY
EMISSIVITY
INFRARED RADIATION
LIGHT SOURCES
MEASURING INSTRUMENTS
MEASURING METHODS
MODULATION
OPTICAL PROPERTIES
OSCILLATIONS
SOLAR SIMULATORS
SPECTROSCOPY
VISIBLE RADIATION
ELECTROMAGNETIC RADIATION
PHYSICAL PROPERTIES
RADIATION SOURCES
RADIATIONS
SURFACE PROPERTIES
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