Nanoscale surface tracking of laser material processing using phase shifting diffraction interferometry.

Area of Science:

• Materials Science
• Optical Metrology
• Chemical Engineering

Background:

• Laser-based chemical vapor deposition (LCVD) is a critical additive manufacturing technique.
• Precise real-time monitoring and control are essential for optimizing LCVD processes, especially for high-precision applications.
• Existing methods may lack the sensitivity or adaptability for extreme conditions.

Purpose of the Study:

• To adapt Phase Shifting Diffraction Interferometry (PSDI) for real-time feedback control of the LCVD process.
• To achieve nanometer-scale sensitivity in monitoring substrate response during LCVD.
• To validate a finite element model for thermomechanical response in laser-heated substrates.

Main Methods:

• Phase Shifting Diffraction Interferometry (PSDI) was employed for in-situ surface measurement.
• Laser-heated BK7 and fused silica substrates were analyzed using PSDI.
• A finite element model was developed and validated against PSDI measurements, incorporating refractive index changes and displacement.
• The model accounted for the kinetics of the thermomechanical response.

Main Results:

• PSDI demonstrated nanometer-scale sensitivity for real-time feedback control of the LCVD process.
• PSDI measurements successfully validated the finite element model for laser-heated substrates.
• Integration of PSDI and the validated thermomechanical model led to enhanced LCVD process control.
• The study confirmed the utility of back-side optical probing for surface tracking in extreme environments.

Conclusions:

• PSDI is a viable technique for achieving high-precision, real-time control in LCVD.
• Accurate thermomechanical modeling, validated by PSDI, is crucial for optimizing LCVD.
• The developed approach is suitable for applications requiring surface monitoring through substrates under harsh conditions.