Rigorous vector-diffraction-based spectral signal model for thickness measurement in chromatic confocal microscopy.

Area of Science:

• Optics and Photonics
• Materials Science
• Metrology

Background:

• Chromatic confocal microscopy (CCM) is vital for precise measurements in materials science and manufacturing.
• Conventional CCM models struggle with accuracy due to light refraction in dense media.
• Existing models fail to account for light dispersion across various aperture angles.

Purpose of the Study:

• To develop an accurate spectral signal model for CCM.
• To enhance the precision of displacement and thickness measurements using CCM.
• To overcome limitations of geometric ray tracing models.

Main Methods:

• Proposed a vector-diffraction-based spectral signal model.
• Incorporated reflectance, transmittance, and phase differences for all aperture angles.
• Utilized the vectorial diffraction method for comprehensive light ray analysis.

Main Results:

• The new model precisely describes spectral signal distribution and peak positions.
• Simulation results show a more accurate thickness calculation model.
• Experimental measurements demonstrated a significant reduction in error from 38 μm to 1 μm for a 1.035 mm plate.

Conclusions:

• The vector-diffraction model offers superior accuracy and reliability for CCM measurements.
• This advancement enhances CCM's performance in materials science and manufacturing.
• The model provides consistent results across diverse sample conditions.