---
title: "Spatial Frequency / MTF calculator — AperiOptic"
description: "Convert lp/mm to cycles and diffraction MTF cutoff. Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/spatial-frequency-mtf"
---

# Spatial Frequency / MTF calculator

Convert lp/mm to cycles and diffraction MTF cutoff.

Category: [Diffraction](https://aperioptic.com/calculators)

Formula: `νcutoff = 1/(λ·N)`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| lp/mm | `lpmm` |  | 100 |
| λ | `lam` | nm | 550 |
| f-number | `N` |  | 5.6 |

## Result with the default inputs

- Period: 10 µm
- Diff. cutoff: 324.6753 lp/mm
- Normalized ν: 0.308

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/spatial-frequency-mtf?lpmm=100`](https://aperioptic.com/calculators/spatial-frequency-mtf?lpmm=100). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Optical transfer function](https://en.wikipedia.org/wiki/Optical_transfer_function)

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

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