Professor RICHARD LEACH's Outputs (204)

Comparison of rigorous scattering models to accurately replicate the behaviour of scattered electromagnetic waves in optical surface metrology (2024)
Journal Article
Hooshmand, H., Pahl, T., Hansen, P.-E., Fu, L., Birk, A., Karamehmedović, M., Lehmann, P., Reichelt, S., Leach, R., & Piano, S. (2025). Comparison of rigorous scattering models to accurately replicate the behaviour of scattered electromagnetic waves in optical surface metrology. Journal of Computational Physics, 521, Article 113519. https://doi.org/10.1016/j.jcp.2024.113519

Rigorous scattering models are based on Maxwell's equations and can provide high-accuracy solutions to model electromagnetic wave scattering from objects. Being able to calculate the scattered field from any surface geometry and considering the effec... Read More about Comparison of rigorous scattering models to accurately replicate the behaviour of scattered electromagnetic waves in optical surface metrology.

Applying machine learning to optical metrology: a review (2024)
Journal Article
Xue, R., Hooshmand, H., Isa, M., Piano, S., & K Leach, R. (2024). Applying machine learning to optical metrology: a review. Measurement Science and Technology, 36(1), Article 012002. https://doi.org/10.1088/1361-6501/ad7878

This literature review investigates the integration of machine learning (ML) into optical metrology, unveiling enhancements in both efficiency and effectiveness of measurement processes. With a focus on phase demodulation, unwrapping, and phase-to-he... Read More about Applying machine learning to optical metrology: a review.

In-situ measurement methods for microscale surface impurities in powder bed fusion: a review (2024)
Journal Article
Koca, A., Hooshmand, H., Leach, R., & Liu, M. (2025). In-situ measurement methods for microscale surface impurities in powder bed fusion: a review. Measurement Science and Technology, 36(1), Article 012001. https://doi.org/10.1088/1361-6501/ad824c

Despite ongoing improvements and optimisation efforts, the powder bed fusion (PBF) process continues to face challenges related to repeatability, robustness, and stability. These challenges can lead to the formation of microscale surface impurities o... Read More about In-situ measurement methods for microscale surface impurities in powder bed fusion: a review.

Evaluating approximate and rigorous scattering models in virtual coherence scanning interferometry for improved surface topography measurement (2024)
Presentation / Conference Contribution
Hooshmand, H., Isa, M. A., Nikolaev, N., Piano, S., & Leach, R. (2024, August). Evaluating approximate and rigorous scattering models in virtual coherence scanning interferometry for improved surface topography measurement. Presented at Optical Manufacturing and Testing 2024, San Diego, USA

In optical metrology, the growing demand for accurate measurement technologies is driven by the increasing applications of three-dimensional (3D) microscopy and imaging. The advancement of these technologies relies on the modelling of the measurement... Read More about Evaluating approximate and rigorous scattering models in virtual coherence scanning interferometry for improved surface topography measurement.

Machine learning-based envelope extraction from downsampled coherence scanning interferometry signal data (2024)
Presentation / Conference Contribution
Xue, R., Hooshmand, H., Isa, M., & Leach, R. (2024, September). Machine learning-based envelope extraction from downsampled coherence scanning interferometry signal data. Presented at Special Interest Conference: Structured & Freeform Surfaces, Nottingham, UK

Extracting focus variation data from coherence scanning interferometric measurements (2024)
Journal Article
Liu, J., Hooshmand, H., Piano, S., Leach, R., Coupland, J., Ren, M., Zhu, L., & Su, R. (2024). Extracting focus variation data from coherence scanning interferometric measurements. Precision Engineering, 88, 699-706. https://doi.org/10.1016/j.precisioneng.2024.04.016

Coherence scanning interferometry (CSI), based on the principle of interference, can achieve sub-nanometer precision for height measurements. On the other hand, focus variation microscopy (FVM), combining the small depth of field of the objective, is... Read More about Extracting focus variation data from coherence scanning interferometric measurements.

Comparison of Fourier optics-based methods for modeling coherence scanning interferometry (2024)
Journal Article
Hooshmand, H., Pahl, T., de Groot, P. J., Lehmann, P., Pappas, A., Su, R., Leach, R., & Piano, S. (2024). Comparison of Fourier optics-based methods for modeling coherence scanning interferometry. Optical Engineering, 63(4), Article 044102. https://doi.org/10.1117/1.OE.63.4.044102

Coherence scanning interferometry (CSI) is a widely used optical method for surface topography measurement of industrial and biomedical surfaces. The operation of CSI can be modeled using approximate physics-based approaches with minimal computationa... Read More about Comparison of Fourier optics-based methods for modeling coherence scanning interferometry.

Vision-based detection and coordinate metrology of a spatially encoded multi-sphere artefact (2023)
Journal Article
Isa, M. A., Leach, R., Branson, D., & Piano, S. (2024). Vision-based detection and coordinate metrology of a spatially encoded multi-sphere artefact. Optics and Lasers in Engineering, 172, Article 107885. https://doi.org/10.1016/j.optlaseng.2023.107885

New developments in vision algorithms prioritise identification and perception over accurate coordinate measurement due to the complex problem of resolving object form and pose from images. Consequently, many vision algorithms for coordinate measurem... Read More about Vision-based detection and coordinate metrology of a spatially encoded multi-sphere artefact.

Review of material measures for surface topography instrument calibration and performance verification (2023)
Journal Article
Pappas, A., Newton, L., Thompson, A., & Leach, R. (2024). Review of material measures for surface topography instrument calibration and performance verification. Measurement Science and Technology, 35(1), Article 012001. https://doi.org/10.1088/1361-6501/acf1b9

As the need for the manufacturing of complex surface topographies increases, traceable measurement with known uncertainties can allow a manufacturing process to remain stable. Material measures are the link in the chain that connects the surface topo... Read More about Review of material measures for surface topography instrument calibration and performance verification.

Comparison of approximate methods for modelling coherence scanning interferometry (2023)
Presentation / Conference Contribution
Hooshmand, H., Pahl, T., de Groot, P. J., Lehmann, P., Pappas, A., Su, R., Leach, R., & Piano, S. Comparison of approximate methods for modelling coherence scanning interferometry. Presented at Modeling Aspects in Optical Metrology IX, Munich, Germany

Coherence scanning interferometry (CSI) is a widely used optical method for surface topography measurement of industrial and biomedical surfaces. The operation of CSI can be modelled using approximate physics-based approaches with minimal computation... Read More about Comparison of approximate methods for modelling coherence scanning interferometry.

High-accuracy robotic metrology for precise industrial manipulation tasks (2023)
Presentation / Conference Contribution
Isa, M. A., Khanesar, M. A., Leach, R. K., Branson, D., & Piano, S. (2023, June). High-accuracy robotic metrology for precise industrial manipulation tasks. Presented at Automated Visual Inspection and Machine Vision V, Munich, Germany

The majority of industrial production processes can be divided into a series of object manipulation and handling tasks that can be adapted for robots. Through significant advances in compliant grasping, sensing and actuation technologies, robots are... Read More about High-accuracy robotic metrology for precise industrial manipulation tasks.

Comparison of coherence scanning interferometry, focus variation and confocal microscopy for surface topography measurement (2023)
Presentation / Conference Contribution
Hooshmand, H., Liu, M., Pappas, A., Thompson, A., Leach, R., & Piano, S. (2023, June). Comparison of coherence scanning interferometry, focus variation and confocal microscopy for surface topography measurement. Presented at Euspen’s 23rd International Conference & Exhibition, Copenhagen, Denmark

The most common optical technologies for surface topography measurement are coherence scanning interferometry (CSI), focus variation microscopy (FV) and imaging confocal microscopy (CM). Due to the benefits and drawbacks of each, these instruments ar... Read More about Comparison of coherence scanning interferometry, focus variation and confocal microscopy for surface topography measurement.

New Standard for Metal Powder Bed Fusion Surface Texture Measurement and Characterisation (2023)
Journal Article
Thompson, A., Newton, L., & Leach, R. (2023). New Standard for Metal Powder Bed Fusion Surface Texture Measurement and Characterisation. Metrology, 3(2), 237-245. https://doi.org/10.3390/metrology3020013

As metal additive manufacturing has been increasingly accepted as a viable method of industrial manufacture, there has been a significant uptake in manufacturers wishing to verify and test their parts through analysis of part surface. However, variou... Read More about New Standard for Metal Powder Bed Fusion Surface Texture Measurement and Characterisation.

A Neural Network Separation Approach for the Inclusion of Static Friction in Nonlinear Static Models of Industrial Robots (2023)
Journal Article
Ahmadieh Khanesar, M., Yan, M., Syam, W. P., Piano, S., Leach, R. K., & Branson, D. (2023). A Neural Network Separation Approach for the Inclusion of Static Friction in Nonlinear Static Models of Industrial Robots. IEEE/ASME Transactions on Mechatronics, 28(6), 3294-3304. https://doi.org/10.1109/TMECH.2023.3262644

Static friction modeling is a critical task to have the accurate robot model. In this article, a neural network separation approach to include nonlinear static friction in models of industrial robots is proposed. For this purpose, the terms correspon... Read More about A Neural Network Separation Approach for the Inclusion of Static Friction in Nonlinear Static Models of Industrial Robots.

Improving the localisation of features for the calibration of cameras using EfficientNets (2023)
Journal Article
Eastwood, J., Gayton, G., Leach, R. K., & Piano, S. (2023). Improving the localisation of features for the calibration of cameras using EfficientNets. Optics Express, 31(5), 7966-7982. https://doi.org/10.1364/OE.478934

Camera-based methods for optical coordinate metrology, such as digital fringe projection, rely on accurate calibration of the cameras in the system. Camera calibration is the process of determining the intrinsic and distortion parameters which define... Read More about Improving the localisation of features for the calibration of cameras using EfficientNets.

Quantitative investigation of the validity conditions for the Beckmann-Kirchhoff scattering model (2022)
Journal Article
Hooshmand, H., Liu, M., Leach, R., & Piano, S. (2022). Quantitative investigation of the validity conditions for the Beckmann-Kirchhoff scattering model. Optical Engineering, 61(12), Article 124113. https://doi.org/10.1117/1.OE.61.12.124113

Approximate and rigorous methods are widely used to model light scattering from a surface. The boundary element method (BEM) is a rigorous model that accounts for polarization and multiple scattering effects. BEM is suitable to model the scattered li... Read More about Quantitative investigation of the validity conditions for the Beckmann-Kirchhoff scattering model.

Autonomous image background removal for accurate and efficient close-range photogrammetry (2022)
Journal Article
Eastwood, J., Leach, R. K., & Piano, S. (2023). Autonomous image background removal for accurate and efficient close-range photogrammetry. Measurement Science and Technology, 34(3), Article 035404. https://doi.org/10.1088/1361-6501/aca497

Close-range photogrammetry can be used to reconstruct dense point clouds of an object with very high surface coverage, making it useful for manufacturing metrology tasks such as part inspection and validation. However, compared to competing technique... Read More about Autonomous image background removal for accurate and efficient close-range photogrammetry.

Evaluating parametric uncertainty using non-linear regression in fringe projection (2022)
Journal Article
Gayton, G., Isa, M., & Leach, R. K. (2023). Evaluating parametric uncertainty using non-linear regression in fringe projection. Optics and Lasers in Engineering, 162, Article 107377. https://doi.org/10.1016/j.optlaseng.2022.107377

Optical coordinate measurement systems, such as fringe projection systems, offer fast, high-density measurements of arbitrary surface topographies. The versatility, speed and information density of fringe projection measurements make them attractive... Read More about Evaluating parametric uncertainty using non-linear regression in fringe projection.

Applications of data fusion in optical coordinate metrology: a review (2022)
Journal Article
Zhang, Z. M., Catalucci, S., Thompson, A., Leach, R., & Piano, S. (2023). Applications of data fusion in optical coordinate metrology: a review. International Journal of Advanced Manufacturing Technology, 124, 1341-1356. https://doi.org/10.1007/s00170-022-10576-7

Data fusion enables the characterisation of an object using multiple datasets collected by various sensors. To improve optical coordinate measurement using data fusion, researchers have proposed numerous algorithmic solutions and methods. The most po... Read More about Applications of data fusion in optical coordinate metrology: a review.

Trinocular vision system for pose determination (2022)
Presentation / Conference Contribution
Isa, M., Khanesar, M., Leach, R., Branson, D., & Piano, S. (2022, October). Trinocular vision system for pose determination. Presented at 37th Annual Meeting of the American Society for Precision Engineering, Bellevue, USA