Characterization of infrared imaging systems

This thesis explores the characterization of infrared (IR) imaging systems by microfabricating and analyzing USAF targets with varying thicknesses (0.6 μm to 5.3 μm) using SU-8 photoresist. The targets were fabricated in a cleanroom environment to ensure controlled conditions and high precision. Designed with well-defined USAF patterns, they served as reliable test samples to assess spectral accuracy and resolution capability due to their tailored and precisely measured parameters. Comparative thickness measurements using surface profilometry (DekTak3ST) and laser confocal microscopy (Keyence VK-X1000) revealed that surface profilometry was more accurate for thin films (< 1 μm) due to challenges in resolving transparent film surfaces via confocal microscopy. High-resolution profiles of USAF targets demonstrated a superior edge quality in laser confocal profiling with 0.08 μm pitch size but were prone to negative artifacts due to the same resolution issue. The Varian 620-IR FTIR imaging system was used to acquire spectra, and 1608 cm⁻¹ peak (aromatic C=C) was analyzed, to evaluate spectral fidelity. While the results followed Beer-Lambert law by showing increasing absorbances for thicker films, thicker films presented baseline linearity challenges. This dataset of well characterized targets provides a strong foundation for validating future IR instrument accuracies as well as IR simulation models.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Ashok, Sandhya

Contributors dc:contributor

• Bhargava, Rohit

• Infrared Imaging Systems
• Imaging Systems
• Characterization
• Fabrication
• Microfabrication
• Fourier Transform Infrared Imaging
• FTIR

Statement dc:rights

• Copyright 2025 Sandhya Ashok

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/129634

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F129634