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Summary
This study reviews conventional methods for optical surface sphericity testing, assessing their real-time interferometry suitability. A digital filtering technique is presented to reduce measurement errors like coherent noise.
Area of Science:
- Optical Engineering
- Metrology
- Interferometry
Background:
- Conventional methods for absolute sphericity testing of optical surfaces exist.
- Real-time interferometry applications of these methods require further investigation.
Purpose of the Study:
- To review and assess conventional sphericity testing methods for real-time interferometry.
- To investigate the application of a specific method to phase-stepping interferometry.
- To analyze measurement errors and introduce noise reduction techniques.
Main Methods:
- Review of conventional absolute sphericity testing techniques.
- Application and examination of a chosen method in phase-stepping interferometry.
- Analysis of measurement errors, including coherent noise.
- Development of a digital spatial filtering technique for noise reduction.
Main Results:
- Assessment of conventional methods' suitability for real-time interferometry.
- Experimental results of deviation measurements on normal surfaces.
- Identification and analysis of measurement errors, particularly coherent noise.
- Demonstration of a digital spatial filtering technique for noise diminution.
Conclusions:
- Certain conventional methods are suitable for real-time interferometry.
- Phase-stepping interferometry can be effectively used for sphericity testing.
- Digital spatial filtering significantly reduces coherent noise in measurements.
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