Lens curvature measurements by shadow projection profilometry
Applied Optics
|November 12, 2010
Summary
This study introduces a novel, non-contact method for precisely measuring lens curvature. The technique uses projected lens shadows and computer analysis, enabling accurate curvature assessment for various lens types.
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.