Maréchal Strehl
Estimate Strehl ratio from RMS wavefront error with the Maréchal relation.
Description
The Maréchal relation estimates Strehl ratio from RMS wavefront error normalized to wavelength.
The Maréchal relation estimates Strehl ratio from RMS wavefront error normalized to wavelength. It is an exponential approximation tied to a wavefront-error convention.1
Estimate Strehl ratio from RMS wavefront error with the Maréchal relation.
When to use Maréchal Strehl
Use this tool to estimate Strehl ratio from RMS wavefront error with the Maréchal relation.
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 Maréchal Strehl 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 rmsWavefrontErrorMeters, wavelengthMeters using the field table and calculation rules, then run the tool.
- Read strehlRatio, strehlPercent. 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 |
|---|---|---|---|
| rmsWavefrontErrorMeters | RMS wavefront error (m) | number; minimum: 0 | Required |
| wavelengthMeters | Wavelength (m) | number; minimum: 0 | Required |
Enter nonnegative RMS error and positive wavelength in meters. Return ratio and percent; zero error gives unity.
Strehl=exp(−(2πRMS/λ)²) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| strehlRatio | Maréchal Strehl estimate | number; minimum: 0; maximum: 1 |
| strehlPercent | Strehl estimate (%) | number; minimum: 0; maximum: 100 |
{
"input": {
"rmsWavefrontErrorMeters": 5e-8,
"wavelengthMeters": 0.000001
},
"output": {
"strehlRatio": 0.906018055788923,
"strehlPercent": 90.6018055788923
}
}Limitations and assumptions
No pupil map or point-spread function is computed, and applicability of the approximation must be assessed separately.
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 Isoplanatic Field Margin: Compare a requested correction field with the measured isoplanatic angle.
References
-
Maréchal Strehl — tool.io
Similar or alternative tools
- Fried Seeing Conversion
Convert Fried parameter to seeing angle at a supplied wavelength.
- Isoplanatic Field Margin
Compare a requested correction field with the measured isoplanatic angle.