> ## Documentation Index
> Fetch the complete documentation index at: https://docs.atomscale.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Ellipsometry

> Timeseries extraction from spectroscopic ellipsometry measurements

Ellipsometry analysis imports spectroscopic ellipsometry data and extracts per-wavelength timeseries for psi, delta, depolarization, and incident intensity. It supports batch file uploads and real-time streaming from supported instruments.

## Overview

The ellipsometry pipeline processes data in three stages:

1. **Data import**: reads raw instrument text exports, handling single files, directories, and compressed archives
2. **Data structuring**: parses measurements into a normalized table with columns for time, wavelength, psi, delta, depolarization, and incident intensity
3. **Timeseries construction**: pivots the table by metric and wavelength, producing one timeseries per (metric, wavelength) pair

### Key Metrics

| Metric             | What It Tells You                                                                                                      |
| ------------------ | ---------------------------------------------------------------------------------------------------------------------- |
| Psi                | Amplitude ratio of p- and s-polarized reflected light, in degrees. Sensitive to film thickness and optical properties. |
| Delta              | Phase difference between p- and s-polarized reflected light, in degrees. Sensitive to thin film changes.               |
| Depolarization     | Fraction of depolarized light. Indicates surface roughness, thickness non-uniformity, or backside reflections.         |
| Incident intensity | Intensity of the incident beam at each wavelength. Useful for monitoring source stability.                             |

Each metric is extracted per wavelength, producing one timeseries per (metric, wavelength) pair with property names like `psi_400.5` or `delta_550.2`.

<Tabs>
  <Tab title="Guide">
    ### Adding Ellipsometry Data

    You can add ellipsometry data in two ways: uploading data files, or streaming live from your instrument.

    #### Upload

    Upload ellipsometry data files through the data management page. The pipeline accepts single files, directories of files, and compressed archives (.zip, .tar, .gz, .tgz, .bz2). Analysis begins automatically once the upload completes.

    ### Viewing Results

    Once processing completes (or during a live stream), ellipsometry data is displayed in the standard chart view.

    **Timeseries chart**: The main analysis view. Each timeseries corresponds to a single metric at a single wavelength (e.g., `psi_400.5` or `delta_550.2`). Use the series toggle in the settings drawer to show or hide individual timeseries.

    **Chart controls**:

    * **X-axis type**: Switch between relative time and absolute timestamps
    * **Pan and zoom**: Navigate along the time axis to focus on specific intervals
    * **Tooltips**: Hover over data points to see values and units
    * **Multiple charts**: Add additional charts and sync them to compare different metrics side by side
  </Tab>

  <Tab title="Technical Details">
    ### Analysis Pipeline

    The ellipsometry pipeline processes data through three stages.

    #### Stage 1: Data Import

    Raw ellipsometry text exports are read from two supported instrument formats:

    | Format    | Input Structure                                                                     |
    | --------- | ----------------------------------------------------------------------------------- |
    | FilmSense | Single text file with embedded wavelength and measurement data                      |
    | Woollam   | Directory of separate files per parameter (psi, delta, depolarization, reflectance) |

    The pipeline handles single files, directories, and compressed archives (.zip, .tar, .gz, .tgz, .bz2).

    #### Stage 2: Data Structuring

    Parsed measurements are assembled into a table with one row per (time, wavelength) observation, containing columns for relative time, wavelength, psi, delta, depolarization, and incident intensity. Rows are sorted by time, then by wavelength.

    #### Stage 3: Timeseries Construction

    The structured table is pivoted by metric and wavelength to produce individual timeseries. Each (metric, wavelength) combination yields one timeseries with a property name like `psi_400.5` or `delta_550.2`. Each metric is normalized before downstream processing.

    #### Streaming

    When running in stream mode, the pipeline operates incrementally. Only new data points are appended to existing timeseries rather than reprocessing from scratch.
  </Tab>
</Tabs>

## Related Documentation

<CardGroup cols={2}>
  <Card title="Detect Anomalies During a Run" icon="bell" href="/platform/guides/detect-anomalies">
    Use ellipsometry timeseries as part of real-time growth monitoring.
  </Card>

  <Card title="Identify Uniformity Issues" icon="chart-area" href="/platform/guides/identify-uniformity-issues">
    Analyze ellipsometry data consistency across a growth.
  </Card>
</CardGroup>