Accelerated measurement and defect characterization on large optical components

Matthias Liedmann; Torsten Machleidt

doi:10.1117/12.2673089

15 August 2023 Accelerated measurement and defect characterization on large optical components

Matthias Liedmann, Torsten Machleidt

Proceedings Volume 12618, Optical Measurement Systems for Industrial Inspection XIII; 126181S (2023) https://doi.org/10.1117/12.2673089
Event: SPIE Optical Metrology, 2023, Munich, Germany

Abstract

Measurement and characterization of small defects on large areas are time consuming but can be accelerated using high speed cameras and GPGPUs (general purpose graphic processing units). A height map of a filter glass with a 50 mm diameter scanned with a spatial sampling of 1 μm must present the data of more than 1000 single scans or 2.5 billion measuring points on a screen. Stitching processes of such data amount exceed the capacity of actual available metrology software packages even while operating on high end PCs. Resampling processes may result in a loss of information about surface roughness and small defects. Batch processing of the single scans is possible but make the interpretation of measuring results complicate and time consuming. Task specific data processing strategies overcome the given limitations. Disturbing residual stitching errors in overlapping zones are avoided and small scratches can still be observed in 3d maps of the complete sample. This simplifies the localization and provide information for preventive measures. Similar but adapted processing strategies are available to visualize local fluctuations of the surface textures. Test was done using the optical profiler smartWLI firebolt. The sensor operates on the measuring principal CSI - coherence scanning (white-light) interferometry and uses a 1.3 MP camera with 935 fps / full resolution. Data are processed in real time using a CUDA programmable NVIDIA graphic board which provides a calculation power of up to 82.6 FP32-TFLOPs. Thus, resulting in acquisition performance of up to approximately 1 single scan per second.

Conference Presentation

Citation Download Citation

Matthias Liedmann and Torsten Machleidt "Accelerated measurement and defect characterization on large optical components", Proc. SPIE 12618, Optical Measurement Systems for Industrial Inspection XIII, 126181S (15 August 2023); https://doi.org/10.1117/12.2673089

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