Lens curvature measurements by shadow projection profilometry.

Area of Science:

• Optical Engineering
• Metrology
• Image Analysis

Background:

• Accurate measurement of lens curvature is critical in optical manufacturing and quality control.
• Existing methods often rely on physical contact or surface properties, limiting their applicability.

Purpose of the Study:

• To develop and validate a non-contact technique for measuring both spherical and aspherical lens curvature.
• To overcome limitations of traditional contact-based measurement methods.

Main Methods:

• Projecting a lens profile's shadow onto a Charge-Coupled Device (CCD) pixel array.
• Utilizing computer video-image analysis for silhouette edge-tracing.
• Applying nonlinear regression analysis with axial tilt correction to calculate curvature.

Main Results:

• The described technique successfully measures lens curvature without surface contact.
• It is independent of surface smoothness, offering broader applicability.
• Accurate curvature determination for spherical and aspherical lenses is achieved.

Conclusions:

• This non-contact shadow projection method provides a robust and versatile solution for lens curvature measurement.
• It offers a significant advancement over traditional contact-based metrology techniques.