Rytov Variance
Calculate plane-wave Rytov variance and classify it with a caller-supplied threshold.
Description
Plane-wave Rytov variance summarizes a constant-turbulence propagation model.
Plane-wave Rytov variance summarizes a constant-turbulence propagation model. A supplied threshold divides the returned weak and strong labels.1
Calculate plane-wave Rytov variance and classify it with a caller-supplied threshold.
When to use Rytov Variance
Use this tool to calculate plane-wave Rytov variance and classify it with a caller-supplied threshold.
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 Rytov Variance 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 refractiveIndexStructureConstant, wavelengthMeters, pathLengthMeters, strongScintillationThreshold using the field table and calculation rules, then run the tool.
- Read rytovVariance, regime. 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 |
|---|---|---|---|
| refractiveIndexStructureConstant | Cn² (m^(-2/3)) | number; minimum: 0 | Required |
| wavelengthMeters | Wavelength (m) | number; minimum: 0 | Required |
| pathLengthMeters | Path length (m) | number; minimum: 0 | Required |
| strongScintillationThreshold | Strong-scintillation threshold | number; minimum: 0 | Required |
Enter nonnegative structure constant, path and threshold with positive wavelength. Return variance and strong at equality or above, otherwise weak.
variance=1.23 Cn²(2π/λ)^(7/6)L^(11/6) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| rytovVariance | Plane-wave Rytov variance | number; minimum: 0 |
| regime | Scintillation regime | string; one of "weak", "strong" |
{
"input": {
"refractiveIndexStructureConstant": 1e-14,
"wavelengthMeters": 0.000001,
"pathLengthMeters": 1000,
"strongScintillationThreshold": 1
},
"output": {
"rytovVariance": 0.3319823217262583,
"regime": "weak"
}
}Limitations and assumptions
No turbulence profile, beam geometry or automatic validity assessment is supplied.
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 Fried Seeing Conversion: Convert Fried parameter to seeing angle at a supplied wavelength. For a complementary task, use Free-Space Link Margin: Calculate a free-space optical link budget from caller-supplied gains, losses, and sensitivity.
References
-
Rytov Variance — tool.io
Similar or alternative tools
- Fried Seeing Conversion
Convert Fried parameter to seeing angle at a supplied wavelength.
- Free-Space Link Margin
Calculate a free-space optical link budget from caller-supplied gains, losses, and sensitivity.