Characterization and optimization of illumination vector for contouring surface form and feature using DSPI

Area of Science:

• Optical Metrology
• Materials Science
• Non-destructive Testing

Background:

• Surface defects critically impact engineering material and structure failure.
• Various contact and non-contact methods exist for surface measurement.
• Speckle pattern interferometry contours surfaces using illumination vectors.

Purpose of the Study:

• Investigate the effect of illumination source position and translation direction on digital speckle pattern interferometry.
• Analyze sensitivity factors for surface height measurement.
• Validate experimental methods for surface form and feature reconstruction.

Main Methods:

• Utilized a digital speckle pattern interferometry system.
• Performed slight translation of the illumination source.
• Conducted theoretical analysis of sensitivity factors.
• Performed experimental validation.

Main Results:

• Off-axis illumination demonstrates higher sensitivity to surface height compared to paraxial illumination.
• Contouring fringes are more sensitive with off-axis illumination.
• Illumination source translation along axial and lateral directions effectively reconstructs surface shape.

Conclusions:

• Illumination source translation in digital speckle pattern interferometry enhances surface measurement capabilities.
• Off-axis illumination is crucial for improved surface height sensitivity.
• This method offers a viable approach for precise surface form and feature analysis.