Design and error calibration of an on-axis deflectometric microscope system

Area of Science:

• Optical Metrology
• Surface Characterization
• Microscopy

Background:

• Microscopic surface measurement demands high accuracy and dynamic range.
• Existing methods can suffer from geometry sensitivity and aberrations due to system miscalibration.
• Accurate metrology is crucial for micro-devices and freeform surfaces.

Purpose of the Study:

• To propose and validate an on-axis deflectometric microscope system (ODMS) for high-accuracy microscopic surface measurement.
• To analyze and mitigate geometrical aberrations caused by system model miscalibration.
• To demonstrate the system's capability for testing diverse micro-scale components.

Main Methods:

• Implementation of a coaxial configuration using a beam splitter in the ODMS.
• Analysis of geometrical aberrations arising from system model miscalibration.
• Application of computer-aided reverse optimization for system calibration.
• Discussion of systematic errors introduced by ODMS components.

Main Results:

• The ODMS demonstrates feasibility and high accuracy through simulations and experiments.
• The proposed calibration method effectively corrects geometrical aberrations.
• The system achieves a large measurable slope range and high spatial resolution.

Conclusions:

• The developed ODMS is a viable metrological tool for microscopic testing.
• The system's compact structure and performance metrics are suitable for freeform surfaces and micro-devices.
• Accurate calibration is essential for mitigating aberrations and ensuring measurement precision.