AO Fitting Strehl

Estimate adaptive-optics fitting variance and Strehl from actuator pitch.

Description

Adaptive-optics fitting error estimates residual phase variance from actuator spacing relative to Fried parameter.

Adaptive-optics fitting error estimates residual phase variance from actuator spacing relative to Fried parameter. Exponential variance gives the modeled Strehl.^[1]

Estimate adaptive-optics fitting variance and Strehl from actuator pitch.

When to use AO Fitting Strehl

Use this tool to estimate adaptive-optics fitting variance and Strehl from actuator pitch.

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 AO Fitting 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 actuatorPitchMeters, friedParameterMeters using the field table and calculation rules, then run the tool.
Read fittingVarianceRad2, estimatedStrehl. 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
actuatorPitchMeters	Actuator pitch (m)	number; minimum: 0	Required
friedParameterMeters	Fried parameter (m)	number; minimum: 0	Required

Enter nonnegative pitch and positive Fried parameter in meters. Return rad² variance and estimated Strehl.

variance=0.28(pitch/r0)^(5/3); Strehl=exp(−variance)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
fittingVarianceRad2	AO fitting-error variance (rad²)	number; minimum: 0
estimatedStrehl	Marechal Strehl estimate	number; minimum: 0; maximum: 1

json

{
  "input": {
    "actuatorPitchMeters": 1,
    "friedParameterMeters": 1
  },
  "output": {
    "fittingVarianceRad2": 0.28,
    "estimatedStrehl": 0.7557837414557255
  }
}

Limitations and assumptions

The fixed fitting coefficient is assumed. No turbulence profile, temporal error, wavefront reconstruction or measured PSF 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 Astigmatic Collimator Design: Estimate separate fast- and slow-axis collimator focal lengths from divergence and target diameter. For a complementary task, use Maréchal Strehl: Estimate Strehl ratio from RMS wavefront error with the Maréchal relation.

References

AO Fitting Strehl — tool.io

Similar or alternative tools

Astigmatic Collimator Design
Estimate separate fast- and slow-axis collimator focal lengths from divergence and target diameter.
Maréchal Strehl
Estimate Strehl ratio from RMS wavefront error with the Maréchal relation.