> For the complete documentation index, see [llms.txt](https://simplemetalens.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://simplemetalens.gitbook.io/docs/smd-pro/tutorial/lens-characterization/aberration-analysis.md).

# Aberration Analysis

This section will walk you through how to analyze lens aberrations using SMD PRO. The analyses are based on the imaging system introduced in [2.2. Imaging](/docs/smd-pro/tutorial/basic-workflow/2.-simulate/2.2.-imaging.md).

## Distortion

See [Distortion](/docs/smd-pro/topical-discussions/aberrations/distortion.md) for the discussion of distortion in a lens system.

### 1) Get Image Height for Ideal Rays

In imaging mode of SIMULATE module, enter parameters as shown in the image below. For the object height 25 µm, h' = -2.58 µm is the image height for ideal rays, as seen in the Paraxial Parameters.

<figure><img src="/files/lZ62yVtFxIQyxwTTYJEN" alt=""><figcaption></figcaption></figure>

### 2) Get Image Height for Real Rays

Run simulation with the parameters shown in the above image. Click the ANALYZE button in the sidebar and look for the imaging simulation results for tangential axis, as shown in the below image. We will take the value of "y at peak intensity" as the image height for real rays, which is -2.76 µm. &#x20;

<figure><img src="/files/MIq9lYn0mwnzMcA3DBw4" alt=""><figcaption></figcaption></figure>

### 3) Calculate Distortion

$$Distortion\ (%)\ = {{-2.76\ +\ 2.58} \over -2.58 } \* 100 = 6.98\ %$$


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