A Single-Frame Deflectometry Method for Online Inspection of Light-Transmitting Components

Area of Science:

• Optical metrology
• Surface inspection
• Industrial measurement systems

Background:

• Transparent materials pose challenges for precise surface form measurements due to complex optical properties.
• Existing methods like structured light struggle with signal-to-noise ratios in industrial settings.
• Efficient real-time inspection techniques for transparent components are lacking.

Purpose of the Study:

• To propose a novel single-frame measurement technique for large-size transparent surfaces using deflectometry.
• To overcome signal-to-noise ratio limitations and diffuse reflection issues inherent in transparent materials.
• To enable efficient and accurate real-time inspection of transparent components in industrial environments.

Main Methods:

• A single-frame deflectometry technique utilizing the reflective characteristics of the measured surface.
• Phase map discretization to separate multiple surface reflection characteristics of transparent devices.
• A simple, low-cost system with two cameras, eliminating the need for phase shifting.

Main Results:

• Achieved measurement accuracy on the order of 10 μm for a 400mm aperture automobile glass.
• Successfully overcame the influence of surface reflection on transparent objects.
• Demonstrated improved efficiency and accuracy in large-sized transparent surface measurements.

Conclusions:

• The proposed single-frame deflectometry method offers a robust solution for measuring large transparent surfaces.
• The technique significantly enhances measurement accuracy and efficiency, overcoming traditional limitations.
• Shows potential for broader industrial applications, including lenses and Heads-Up Display components.