Adaptive imaging system with spatial light modulator for robust shape measurement of partially specular objects

Area of Science:

• Optical Engineering
• Metrology
• Image Processing

Background:

• Specular surfaces in imaging systems often cause pixel saturation, leading to smearing and blooming.
• These saturation issues hinder accurate 3D shape measurement of objects with partially specular surfaces using structured light methods.

Purpose of the Study:

• To develop a 3D shape measurement system with an advanced dynamic range for objects with specular surfaces.
• To overcome the limitations of conventional optical profiling methods caused by pixel saturation.

Main Methods:

• Integration of a phase-based profiling system with an adaptive spatial light modulator (SLM) in the imaging path.
• Real-time control of pixel transmittance using SLM feedback signals based on input image monitoring.
• Extraction of phase information from non-saturated fringe patterns captured by the CCD camera.

Main Results:

• The proposed system effectively prevents CCD image sensor saturation by controlling pixel transmittance.
• Accurate phase information was successfully extracted from previously unmeasurable saturated areas.
• Experimental verification demonstrated the system's capability for precise 3D shape measurement of objects with specular surfaces.

Conclusions:

• The developed system offers an advanced adaptive dynamic range for 3D shape measurement.
• It successfully addresses the challenges posed by pixel saturation in imaging specular surfaces.
• This method provides a significant improvement over conventional shape measurement techniques.