---
title: "Multiphoton PSF Volume calculator — AperiOptic"
description: "Lateral & axial PSF for two-photon excitation. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/multiphoton-psf-volume"
---

# Multiphoton PSF Volume calculator

Lateral & axial PSF for two-photon excitation.

Category: [Laser & Ultrafast](https://aperioptic.com/calculators)

Formula: `wxy = 0.320·λ/(√2·NA) (NA ≤ 0.7), 0.325·λ/(√2·NA^0.91) (NA > 0.7) · wz = 0.532·λ/(√2·(n-√(n²-NA²)))`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| λ | `lam` | nm | 920 |
| NA | `NA` |  | 1 |
| Index n | `n` |  | 1.33 |

## Result with the default inputs

- Lateral wxy: 211.4249 nm
- Axial wz: 763.7674 nm

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/multiphoton-psf-volume?lam=920`](https://aperioptic.com/calculators/multiphoton-psf-volume?lam=920). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Two-photon excitation microscopy](https://en.wikipedia.org/wiki/Two-photon_excitation_microscopy)

[All optics calculators](https://aperioptic.com/calculators)

---

The interactive page: https://aperioptic.com/calculators/multiphoton-psf-volume (AperiOptic runs in the browser; free, no account). Every page of the site as Markdown: https://aperioptic.com/llms.txt