Data Import and Export

This chapter covers the four data-exchange tasks that matter in daily use: importing refractive-index files, importing incident-spectrum files, exporting results, and using the Data page to inspect the current model state. The focus is format, validation, and failure isolation.

Scope of this chapter

The Data page displays the internal data structure of the current model configuration and calculation results in JSON format.

Refractive-index files: format and import rules

The current parser accepts .nk and .txt. The file is read as a sequence of comment lines and data rows.

The file does not need to be pre-sorted. The parser reorders all arrays together and preserves row alignment.

Hard validation rules for refractive-index files

Refractive-index file format

# ITO measured data
# source: ellipsometry fit
400 1.95 0.12
500 1.90 0.10
600 1.87 0.09

For a birefringent file:

# Birefringent sample
400 1.70 0.00 1.75 0.00
500 1.69 0.00 1.74 0.00
600 1.68 0.00 1.73 0.00

Refractive-index database as a data source

In addition to local file upload, the File mode on the Structure page provides a Database button that opens the built-in refractiveindex.info material catalog. Database materials are stored in the same data structure as uploaded files, but they retain a database link that enables version tracking and updates.

For database material management, see Structure Configuration - Refractive-Index Database and Structure Configuration - RI Status Check.

Refractive-index interpolation methods

When a layer or surrounding medium loads refractive-index data via File mode, the software must interpolate between data points to obtain index values at arbitrary wavelengths. The Interpolation dropdown provides three methods:

Wavelength coverage check

Before running a calculation, the software automatically verifies that the refractive-index data wavelength range of every File-mode layer and surrounding medium fully covers the wavelength sampling range configured in the Optics page. If any layer fails this check, the run is blocked.

The error message format is: {layer name}: Refractive Index (RI) data range {dataFrom}–{dataTo} nm does not cover Wavelength Sampling {reqFrom}–{reqTo} nm.

Corrective actions:

1. Replace the refractive-index material with one that has a wider wavelength range.
2. Or reduce the wavelength sampling range in the Optics page so that it falls within the existing data's valid interval.

Incident-spectrum files: format and import rules

The current parser accepts .txt and .pl. Unlike refractive-index files, incident-spectrum files must contain exactly two columns.

Hard validation rules for incident-spectrum files

Incident-spectrum file format

# Custom LED spectrum
400 0.12
450 0.45
500 0.92
550 1.00
600 0.61

If Visible Color will also be enabled later, make sure this spectrum is consistent with the active wavelength sampling range, or the color calculation will be blocked by the wavelength-range rules.

Export: result data and round-trip source data

The app currently supports two export categories.

Important behaviors of source-data export:

1. Refractive-index and incident-spectrum exports are validated again before download.
2. description is written back as # comment lines so the exported file remains compatible with the import parser.
3. Birefringent refractive-index exports preserve nExt / kExt.
4. TXT export uses a plain-text layout that can be imported again directly.

Result CSV interpretation:

• Regular calculation results export as Wavelength_nm, Value;
• Sweep CSV exports parameter columns first, then wavelength columns;
• Sweep CSV is meant for batch comparison, not as a simple single-curve file.

The Data page: inspect the active model directly

The Data page is not a result page. It exposes the current frontend model state as structured data.

Each panel supports expand/collapse. Use it in these situations:

1. after importing a file, confirm the data actually landed in the intended field;
2. when sweep or optimizer reports a path issue, verify the exact path names in the structured data;
3. before saving or documenting an example case, confirm that the model state matches the intended setup.

Troubleshooting order

When import succeeds but the result still looks wrong, use this order:

1. check that the source file has a strictly increasing wavelength column and consistent units;
2. use the Data page to verify array lengths and key fields after import;
3. return to Structure or Optics and confirm the imported data are actually enabled in the active model.

The check order is: format -> binding -> modeling.