Substrate Refractive-Index Fitting

Introduction

This topic focuses on fitting the refractive index of substrate materials (for example, glass). It is typically used when the substrate index is unknown or needs to be recalibrated before coating-material fitting.

Procedure

1. Prepare measurement data for substrate-only samples (T/R or equivalent photometric data).
2. Open the index-fitting module and load a substrate-oriented configuration template.
3. Set fitting bounds and stop criteria for substrate n/k behavior.
4. Run fitting and compare simulated spectra against measured spectra.
5. Save qualified substrate index results to the material database.

Example

A clear glass substrate is measured at multiple wavelengths. After loading the measurement spectrum and enabling substrate fitting, optimization converges within configured cycles, and the fitted n-curve is saved as a reusable substrate material.

Notes

• Use clean substrate-only samples to avoid coating-layer interference.
• Multi-angle data can improve stability and uniqueness of the fitted result.
• Validate fitted substrate data on at least one independent sample before production use.