Beam-Expander Magnification
Calculate signed beam-expander magnification, output diameter, and lens configuration.
Description
An ideal two-lens beam expander scales beam diameter by the magnitude of its focal-length ratio.
An ideal two-lens beam expander scales beam diameter by the magnitude of its focal-length ratio. Focal-length signs determine the returned configuration label.1
Calculate signed beam-expander magnification, output diameter, and lens configuration.
When to use Beam-Expander Magnification
Use this tool to calculate signed beam-expander magnification, output diameter, and lens configuration.
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 Beam-Expander Magnification 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 firstFocalLengthMillimeters, secondFocalLengthMillimeters, inputBeamDiameterMillimeters using the field table and calculation rules, then run the tool.
- Read signedMagnification, outputBeamDiameterMillimeters, configuration. 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 |
|---|---|---|---|
| firstFocalLengthMillimeters | First-lens focal length (mm) | number | Required |
| secondFocalLengthMillimeters | Second-lens focal length (mm) | number | Required |
| inputBeamDiameterMillimeters | Input beam diameter (mm) | number; minimum: 0 | Required |
Enter finite focal lengths with nonzero first length and nonnegative input diameter in mm. Return signed ratio, diameter and galilean for opposite signs, otherwise keplerian.
signedMagnification=f2/f1; outputDiameter=|magnification|×inputDiameter Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| signedMagnification | Signed angular magnification | number |
| outputBeamDiameterMillimeters | Output beam diameter (mm) | number; minimum: 0 |
| configuration | Lens configuration | string; one of "galilean", "keplerian" |
{
"input": {
"firstFocalLengthMillimeters": -25,
"secondFocalLengthMillimeters": 100,
"inputBeamDiameterMillimeters": 2
},
"output": {
"signedMagnification": -4,
"outputBeamDiameterMillimeters": 8,
"configuration": "galilean"
}
}Limitations and assumptions
A zero second focal length is accepted and labeled keplerian. No lens spacing, aberration, clear aperture or usable configuration is verified.
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 Brightness Conservation: Measure brightness retention through a tapered double-clad section against a caller limit.
References
-
Beam-Expander Magnification — tool.io
Similar or alternative tools
- Astigmatic Collimator Design
Estimate separate fast- and slow-axis collimator focal lengths from divergence and target diameter.
- Brightness Conservation
Measure brightness retention through a tapered double-clad section against a caller limit.