Evaluation of concave seismic isolator surfaces using LCD null-screens

Area of Science:

• Metrology
• Mechanical Engineering
• Materials Science

Background:

• The sliding seismic isolator industry needs advanced metrology for manufacturing concave surfaces.
• High-precision geometries are crucial for controlled friction and predictable dynamic performance.

Purpose of the Study:

• To introduce a novel null-screen method for characterizing concave surfaces.
• To enable single-shot measurement of global shape and local defects.

Main Methods:

• Development of a null-screen method utilizing programmable dot patterns.
• Integration and alignment of a test system for geometric parameter extraction.
• Experimental validation on two sliding surface prototypes.

Main Results:

• The method accurately characterizes both global shape and local defects.
• Measurements show radius of curvature deviations under 1%.
• Root-mean-square differences in surface shape are below 102 µm.

Conclusions:

• The novel null-screen method is effective for high-precision metrology of concave surfaces.
• This technology meets the demanding requirements of the sliding seismic isolator industry.
• It ensures geometric accuracy for improved seismic isolation performance.