Fried Seeing Conversion
Convert Fried parameter to seeing angle at a supplied wavelength.
Description
A Fried-parameter seeing estimate relates atmospheric coherence length to angular image width.
A Fried-parameter seeing estimate relates atmospheric coherence length to angular image width. Wavelength and Fried parameter must describe the same observing basis.1
Convert Fried parameter to seeing angle at a supplied wavelength.
When to use Fried Seeing Conversion
Use this tool to convert Fried parameter to seeing angle at a supplied wavelength.
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 Fried Seeing Conversion 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 friedParameterMeters, wavelengthMeters using the field table and calculation rules, then run the tool.
- Read seeingRadians, seeingArcseconds. 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 |
|---|---|---|---|
| friedParameterMeters | Fried parameter r0 (m) | number; minimum: 0 | Required |
| wavelengthMeters | Wavelength (m) | number; minimum: 0 | Required |
Enter positive wavelength and r0 in meters. Return radians and arcseconds.
seeingRadians=0.98λ/r0; arcseconds=radians×206264.80624709636 Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| seeingRadians | Seeing angle (rad) | number; minimum: 0 |
| seeingArcseconds | Seeing angle (arcsec) | number; minimum: 0 |
{
"input": {
"friedParameterMeters": 0.1,
"wavelengthMeters": 5e-7
},
"output": {
"seeingRadians": 0.0000049,
"seeingArcseconds": 1.010697550610772
}
}Limitations and assumptions
No turbulence-profile inference, telescope diffraction or exposure-time correction is included.
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 Rytov Variance: Calculate plane-wave Rytov variance and classify it with a caller-supplied threshold. For a complementary task, use Isoplanatic Field Margin: Compare a requested correction field with the measured isoplanatic angle.
References
-
Fried Seeing Conversion — tool.io
Similar or alternative tools
- Rytov Variance
Calculate plane-wave Rytov variance and classify it with a caller-supplied threshold.
- Isoplanatic Field Margin
Compare a requested correction field with the measured isoplanatic angle.