Physics

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Laser Beam Expander Calculator.

Calculate beam-expander magnification from input and output diameters.

On-device calculationNo signup

Set your values

Results update as you type.

02 / ANSWER

Input beam diameter

Output beam diameter

Magnification

0.000000×

Results update automatically as you type.

Use Cases

Optical System Design

Determine the required magnification when selecting a beam expander to achieve a desired output beam size from a known input beam.

Example: Input 2 mm, output 10 mm → magnification 5x

Laboratory Setup Verification

Verify the actual magnification of an existing beam expander by measuring input and output diameters.

Example: Measure 3 mm input and 15 mm output → 5x

Frequently Asked Questions

How do I calculate the magnification of a laser beam expander?: Enter the input beam diameter and the output beam diameter in meters. The calculator divides the output diameter by the input diameter to give the magnification factor.
What units should I use for the beam diameters?: Both input and output beam diameters must be entered in meters (m). Ensure you convert from millimeters or micrometers to meters before entering values.
Can this calculator be used for any type of laser?: Yes, as long as you know the beam diameters at the input and output of the expander. The magnification is purely geometric and independent of laser wavelength or power.

Tips & Common Mistakes

Tips

Ensure both diameters are in meters before entering them to avoid unit conversion errors.
For Gaussian beams, use the 1/e² diameter for consistent magnification calculations.
Double-check your measurements: small errors in diameter can lead to noticeable magnification differences.
Use the result to compare with the expander's specified magnification to verify performance.

Common Mistakes to Avoid

Mixing units, such as entering input in millimeters and output in meters, which leads to incorrect magnification.
Using the radius instead of the diameter; the calculator expects full beam diameters.
Assuming magnification is the ratio of areas; it is the ratio of diameters.

Last updated: August 13, 2026

Use Cases

Optical System Design

Determine the required magnification when selecting a beam expander to achieve a desired output beam size from a known input beam.

Example: Input 2 mm, output 10 mm → magnification 5x

Laboratory Setup Verification

Verify the actual magnification of an existing beam expander by measuring input and output diameters.

Example: Measure 3 mm input and 15 mm output → 5x

Frequently Asked Questions

How do I calculate the magnification of a laser beam expander?

Enter the input beam diameter and the output beam diameter in meters. The calculator divides the output diameter by the input diameter to give the magnification factor.

What units should I use for the beam diameters?

Both input and output beam diameters must be entered in meters (m). Ensure you convert from millimeters or micrometers to meters before entering values.

Can this calculator be used for any type of laser?

Yes, as long as you know the beam diameters at the input and output of the expander. The magnification is purely geometric and independent of laser wavelength or power.

Tips & Common Mistakes

Tips

Ensure both diameters are in meters before entering them to avoid unit conversion errors.
For Gaussian beams, use the 1/e² diameter for consistent magnification calculations.
Double-check your measurements: small errors in diameter can lead to noticeable magnification differences.
Use the result to compare with the expander's specified magnification to verify performance.

Common Mistakes to Avoid

Mixing units, such as entering input in millimeters and output in meters, which leads to incorrect magnification.
Using the radius instead of the diameter; the calculator expects full beam diameters.
Assuming magnification is the ratio of areas; it is the ratio of diameters.

Use Cases

Optical System Design

Determine the required magnification when selecting a beam expander to achieve a desired output beam size from a known input beam.

Example: Input 2 mm, output 10 mm → magnification 5x

Laboratory Setup Verification

Verify the actual magnification of an existing beam expander by measuring input and output diameters.

Example: Measure 3 mm input and 15 mm output → 5x

Frequently Asked Questions

How do I calculate the magnification of a laser beam expander?

Enter the input beam diameter and the output beam diameter in meters. The calculator divides the output diameter by the input diameter to give the magnification factor.

What units should I use for the beam diameters?

Both input and output beam diameters must be entered in meters (m). Ensure you convert from millimeters or micrometers to meters before entering values.

Can this calculator be used for any type of laser?

Yes, as long as you know the beam diameters at the input and output of the expander. The magnification is purely geometric and independent of laser wavelength or power.

Tips & Common Mistakes

Tips

Ensure both diameters are in meters before entering them to avoid unit conversion errors.
For Gaussian beams, use the 1/e² diameter for consistent magnification calculations.
Double-check your measurements: small errors in diameter can lead to noticeable magnification differences.
Use the result to compare with the expander's specified magnification to verify performance.

Common Mistakes to Avoid

Mixing units, such as entering input in millimeters and output in meters, which leads to incorrect magnification.
Using the radius instead of the diameter; the calculator expects full beam diameters.
Assuming magnification is the ratio of areas; it is the ratio of diameters.