Improved micro topography measurement by LCoS-based fringe projection and z-stitching

Schwab, Xavier; Köhler, Christian; Körner, Klaus; Eichhorn, N.

doi:10.1117/12.781822

Cited by 8 publications

(5 citation statements)

References 16 publications

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“…The types of objects were two aluminium surfaces (polished and normal), a white ceramic plate, and a glass USAF calibration plate. These surfaces, except for the glass substrate were measured using the fringe projection microscope [22]. The glass substrate was measured using a video microscope based on Leica MZ 12.5 with 2x zoom, an objective with 0.63x magnification, and a PCO Pixelfly camera (6.45µm pitch, 1200 x 760 pixel resolution).…”

Section: Exemplary Resultsmentioning

confidence: 99%

Assistant systems for efficient multiscale measurement and inspection

et al. 2011

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Optical inspection systems constitute hardware components (e.g. measurement sensors, lighting systems, positioning systems etc.) and software components (system calibration techniques, image processing algorithms for defect detection and classification, data fusion, etc.). Given an inspection task choosing the most suitable components is not a trivial process and requires expert knowledge. For multiscale measurement systems, the optimization of the measurement system is an unsolved problem even for human experts. In this contribution we propose two assistant systems (hardware assistant and software assistant), which help in choosing the most suitable components depending on the task considering the properties of the object (e.g. material, surface roughness, etc.) and the defects (e.g. defect types, dimensions, etc.). The hardware assistant system uses general rules of thumb, sensor models/simulations and stored expert knowledge to specify the sensors along with their parameters and the hierarchy (if necessary) in a multiscale measurement system. The software assistant system then simulates many measurements with all possible defect types for the chosen sensors. Artificial neural networks (ANN) are used for pre-selection and genetic algorithms are used for finer selection of the defect detection algorithms along with their optimized parameters. In this contribution we will show the general architecture of the assistant system and results obtained for the detection of typical defects on technical surfaces in the micro-scale using a multiscale measurement system.

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Section: Exemplary Resultsmentioning

confidence: 99%

Assistant systems for efficient multiscale measurement and inspection

et al. 2011

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“…In the literature, the method is mostly used for geometrical shape measurements on different scales (down to the size of microfibres) [ 42 , 45 , 46 , 47 ] or in-process monitoring for LPBF [ 48 , 49 , 50 , 51 ]. Fringe projection was used for metal AM surface topography measurement by Whip et al [ 23 ] and Zheng et al in comparison with focus variation microscopy [ 43 ].…”

Section: Materials and Methodsmentioning

confidence: 99%

Comparison of Optical and Stylus Methods for Surface Texture Characterisation in Industrial Quality Assurance of Post-Processed Laser Metal Additive Ti-6Al-4V

et al. 2023

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Additive manufacturing technologies enable lightweight, functionally integrated designs and development of biomimetic structures. They contribute to the reduction in material waste and decrease in overall process duration. A major challenge for the qualification for aerospace applications is the surface quality. Considering Ti-64 laser powder bed fusion (LPBF) parts, particle agglomerations and resulting re-entrant features are characteristic of the upper surface layer. Wet-chemical post-processing of the components ensures reproducible surface quality for improved fatigue behaviour and application of functional coatings. The 3D SurFin® and chemical milling treatments result in smoother surface finishes with characteristic properties. In order to characterise these surfaces, three methods for surface texture measurement (contact and non-contact) were applied, namely confocal microscopy, fringe projection and stylus profilometry. The aim of this work was to show their suitability for measurement of laser powder bed fusion as-built and post-processed surfaces and compare results across the evaluated surface conditions. A user-oriented rating of the methods, summarising advantages and disadvantages of the used instruments specifically and the methods in general, is provided. Confocal microscopy reaches the highest resolution amongst the methods, but measurements take a long time. The raw data exhibit large measurement artefacts for as-built and chemically milled conditions, requiring proper data post-processing. The stylus method can only capture 2D profiles and the measurement was restricted by particle agglomerations and craters. However, the method (process and instrument) is entirely standardised and handheld devices are inexpensive, making it accessible for a large group of users. The fringe projection method was the quickest and easiest regarding measurement and data post-processing. Due to large areal coverage, reproduction of location when performing repeat measurements is possible. The spatial resolution is lower than for confocal microscopy but is still considered sufficiently high to characterise the investigated surface conditions.

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“…Hence, only four degrees of freedom are available for the positioning. The sensors are a zoomable fringe projection microscope with various zoom levels, further described in [15,36], as well as a chromatic confocal point sensor.…”

Section: Examplesmentioning

confidence: 99%

View and sensor planning for multi-sensor surface inspection

Gronle

2016

Surf. Topogr.: Metrol. Prop.

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Modern manufacturing processes enable the precise fabrication of high-value parts with high precision and performance. At the same time, the demand for flexible on-demand production of individual objects is continuously increasing. These requirements can only be met if inspection systems provide appropriate answers. One solution is the use of flexible, multi-sensor setups where multiple optical sensors with different fields of application are combined in one system. However, the challenge is then to assist the user in planning the inspection for individual parts. A manual planning requires an expert knowledge of the performance and functionality of every sensor. Therefore, software assistant systems help the user to objectively select the right sensors for a given inspection task. The planning step becomes still more difficult if the manufactured part has a complex form. The implication is that a sensor's position must also be part of the planning process since it significantly influences the quality of the inspection. This paper describes a view and sensor planning approach for a multi-sensor surface inspection system in the context of optical topography measurements in the micro-and meso-scale range. In order to realize an online processing of the assistant system, a significant part of the calculations are done on the graphics processing unit (GPU).

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Improved micro topography measurement by LCoS-based fringe projection and z-stitching

Cited by 8 publications

References 16 publications

Assistant systems for efficient multiscale measurement and inspection

Assistant systems for efficient multiscale measurement and inspection

Comparison of Optical and Stylus Methods for Surface Texture Characterisation in Industrial Quality Assurance of Post-Processed Laser Metal Additive Ti-6Al-4V

View and sensor planning for multi-sensor surface inspection

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