3D infrared thermospectroscopic imaging

Area of Science:

• Spectroscopy
• Tomography
• Infrared Imaging

Background:

• Multispectral imaging provides detailed spectral information.
• Tomography reconstructs 3D structures from 2D projections.
• Infrared thermography offers non-contact temperature and chemical composition analysis.

Purpose of the Study:

• To develop and validate a 3D multispectral tomography technique in the middle wavelength infrared (MWIR) range.
• To reconstruct 3D spatial cubes of absorptivity and proper emission from semi-transparent materials.
• To demonstrate the capability of the technique for rapid, high-resolution 3D thermo-chemical imaging.

Main Methods:

• Utilized a middle wavelength infrared (MWIR) camera (1.5–5.5 μm) and a multispectral IR monochromator (400 nm–20 μm).
• Employed a sample on a rotary stage to acquire transmittance projections at multiple angular positions.
• Reconstructed 3D absorptivity and emission cubes using a back-projection method based on inverse Radon transform.

Main Results:

• Successfully performed rapid IR absorptivity tomography of a metallic screw in under 1 minute.
• Obtained 3D absorptivity and emission tomographies of a burner flame and microfluidic PFA tubing with water and ethanol.
• Demonstrated the ability to capture detailed 3D thermo-chemical information in complex semi-transparent media.

Conclusions:

• The 3D Infrared Thermospectroscopic Imaging (3DITI) method effectively provides 3D thermo-chemical data for complex semi-transparent media.
• The technique enables rapid, high-resolution 3D reconstruction of material properties.
• The method generates large datasets, presenting challenges in data acquisition, storage, and processing.