Photothermal Diffusivity
Infer thermal diffusivity from photothermal-wave phase lag at a known offset.
Description
A photothermal phase model estimates diffusivity from modulation frequency, offset and phase lag.
A photothermal phase model estimates diffusivity from modulation frequency, offset and phase lag. The supplied lag is assumed to follow the chosen diffusion relation.1
Infer thermal diffusivity from photothermal-wave phase lag at a known offset.
When to use Photothermal Diffusivity
Use this tool to infer thermal diffusivity from photothermal-wave phase lag at a known offset.
Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
How to use Photothermal Diffusivity and understand its results
- Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
- Enter modulationFrequencyHertz, measurementOffsetMeters, phaseLagRadians using the field table and calculation rules, then run the tool.
- Read thermalDiffusivitySquareMetersPerSecond. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| modulationFrequencyHertz | Modulation frequency (Hz) | number; minimum: 0 | Required |
| measurementOffsetMeters | Measurement offset (m) | number; minimum: 0 | Required |
| phaseLagRadians | Thermal-wave phase lag (rad) | number; minimum: 0 | Required |
Enter nonnegative frequency/offset and positive phase lag in radians. Return m²/s.
diffusivity=πfrequency×offset²/phaseLag² Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| thermalDiffusivitySquareMetersPerSecond | Thermal diffusivity (m²/s) | number; minimum: 0 |
{
"input": {
"modulationFrequencyHertz": 1,
"measurementOffsetMeters": 0.001,
"phaseLagRadians": 3.141592653589793
},
"output": {
"thermalDiffusivitySquareMetersPerSecond": 3.1830988618379064e-7
}
}Limitations and assumptions
No phase fitting, layered geometry, boundary conditions or material validation is performed.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Nanorod Heating Estimate: Estimate adiabatic sample heating from absorbed nanorod illumination. For a complementary task, use Thermal-Lens Coefficient: Calculate measured thermal-lens dioptric-power change per watt of pump-power change.
References
-
Photothermal Diffusivity — tool.io
Similar or alternative tools
- Nanorod Heating Estimate
Estimate adiabatic sample heating from absorbed nanorod illumination.
- Thermal-Lens Coefficient
Calculate measured thermal-lens dioptric-power change per watt of pump-power change.