Fast topographic optical imaging using encoded search focal scan

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: March 7, 2024

Abstract A central quest in optics is to rapidly extract quantitative information from a sample. Existing topographical imaging tools allow non-contact and three-dimensional measurements at the micro nanoscales are essential applications including precision engineering optical quality control. However, these techniques involve acquiring focal stack of images, time-consuming process that prevents measurement moving samples. Here, we propose method for increasing speed topographic by orders magnitude. Our approach involves collecting reduced set each integrated during full scan, whilst illumination synchronously modulated exposure. By properly designing modulation sequence image, unambiguous reconstruction object height map achieved using far fewer images than conventional methods. We describe theoretical foundations our technique, characterise its performance, demonstrate sub-micrometric over 100 µm range static dynamic systems rates as high 67 topographies per second, limited camera frame rate. The technique ease implementation could enable paradigm shift metrology, allowing real-time characterisation large or

Language: Английский

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Prediction of mechanical properties of LPBF built part based on process monitoring and Gaussian process regression

Measurement Science and Technology, Journal Year: 2024, Volume and Issue: 35(8), P. 085603 - 085603

Published: April 25, 2024

Abstract As a highly promising technology in additive manufacturing, the laser powder bed fusion has only limited application due to its low reproducibility. In this study, image information of 316L specimen after scanning and paving each layer was acquired by complementary metal–oxide–semiconductor industrial camera. The important features were selected, extracted quantificated analyzing tensile test results. Finally, combined with power, quantified as input Gaussian process regression model based on optimization algorithm grid search predict strength specimen. results show that quantized have significant improvement effect, coefficient determination ( R 2 ) is improved from 63% 90.57% compared using power input.

Language: Английский

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Sparse domain robust denoising method in optically-sectioned structured illumination microscopy for complex surface measurement

Optics and Lasers in Engineering, Journal Year: 2024, Volume and Issue: 180, P. 108338 - 108338

Published: May 29, 2024

Language: Английский

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Scan-less microscopy based on acousto-optic encoded illumination

Nanophotonics, Journal Year: 2024, Volume and Issue: 13(1), P. 63 - 73

Published: Jan. 1, 2024

Abstract Several optical microscopy methods are now available for characterizing scientific and industrial processes at sub-micron resolution. However, they often ill-suited imaging rapid events. Limited by the trade-off between camera frame-rate sensitivity, or need mechanical scanning, current microscopes optimized hundreds of frames-per-second (fps), well-below what is needed in such as neuronal signaling moving parts manufacturing lines. Here, we present a scan-less technology that allows sub-micrometric thousands fps. It based on combining single-pixel with parallelized encoded illumination. We use two acousto-optic deflectors (AODs) placed Mach–Zehnder interferometer drive them simultaneously multiple unique acoustic frequencies. As result, orthogonal light stripes obtained interfere sample plane, forming two-dimensional array flickering spots – each its modulation frequency. The from collected single photodiode that, after spectrum analysis, image reconstruction speeds only limited AOD’s bandwidth laser power. describe working principle our approach, characterize performance function number pixels up to 400 × dynamic events 5000

Language: Английский

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Novel chromatic focus variation microscopy for surface metrology

Optics Express, Journal Year: 2024, Volume and Issue: 32(20), P. 35527 - 35527

Published: Aug. 27, 2024

Optical metrology plays a vital role in wide range of research and inspection areas the industry. At present, market offers variety optical instruments, among which focus variation microscope stands out for its capability measuring steep surfaces with high slopes. The traditional (FV) instrument mechanically scans surface by sweeping focal plane objective lens using linear motion stages simultaneously capturing images at different scanning positions, forming stack images. mechanical require regular maintenance calibration to ensure accuracy over time. Another issue associated methods is their physical size, creates limiting factor compactness in-situ measurement applications. This work proposes chromatic (CFV) method that replaces wavelength mechanism overcome above limitations. Unlike variation, CFV system employs dispersive (i.e. chromatically aberrated lens) axially shift along axis provide vertical/depth scanning. approach brings significant enhancements speed reduces size on-machine tasks. In this paper, detailed analysis performance conducted, then proposed validated samples including step height 30 µm sine wave shape peak-to-valley amplitude 19 µm. experiment results were compared those from state-of-the-art commercial (Alicona G5), showed good agreement between two. Furthermore, discussions are provided investigate measurement’s accuracy.

Language: Английский

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Investigation of Focus Variation Microscopy Immunity to Vibrations

Precision Engineering, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 1, 2024

Language: Английский

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Robust measurement of surface topography for additive manufacturing using imaging confocal microscopy

Published: Aug. 15, 2023

Additive manufacturing (AM) has brought a new level of innovation to the production metal parts, allowing for greater design freedom and on-demand fabrication capabilities. However, measurement resulting surface texture increased difficulties. Whilst optical techniques provide fast measurements, high irregularities, large range scales features, variations in reflectivity largely compromise performance. In practice, conventional systems have an insufficient field-of-view (FOV) or produce excessive amount artifacts. We present system optimized measure AM featuring sufficiently wide capture interest, numerical aperture (NA). integrated commercially available objective (SHR Plan Apo 2×, Nikon) with custom-designed tube lens measuring head, achieving magnification 4.2× effective NA 0.26. The implements confocal-like HiLo technique, we experimentally demonstrate successful characterisation parts. Furthermore, report discuss 6×/0.45 microscope objective, great promise Additionally, explore dynamic (HDR) approaches tackle issue variation. Multiple low images taken at illumination intensities are combined reconstruct single topography map. all, combination system, capable capturing scale spatial HDR capability offers versatile solution that can be used variety scientific industrial contexts.

Language: Английский

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Sparse Domain Robust Denoising Pipeline in Optically-Sectioned Structured Illumination Microscopy for Complex Surface Measurement

Published: Jan. 1, 2023

With rapid advancements in precision micro/nano-systems across various industries, the increasing complexity of product surfaces (e.g., high surface slope, large reflectivity differences, or roughness) poses low signal-to-noise (SNR) challenges for reliable three-dimensional measurements. While optically sectioned structured illumination microscopy offers good adaptability to features, its measurement performance on complex is still hindered by noise, massive outliers, and non-measurement point problems. In this paper, we introduce a novel sparse domain robust denoising pipeline OS-SIM address low-SNR measurement. Specifically, our approach divides process into two distinct paths: low-frequency path focuses exploring intrinsic sparsity nonlocal self-similarity image minimize noise signals an artifact-free manner, whereas complementary high-frequency utilizes modulation-contrast-based weighting algorithm provide clean signals. Finally, fusing from both paths, obtain nearly full-resolution images. Measurement experiments test samples demonstrate efficiency consistently reconstruction quality proposed method different topographies.

Language: Английский

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Areal surface measurement using chromatic focus variation

Published: Oct. 20, 2023

Optical metrology is an essential measurement technology across various research and inspection domains. Focus variation instruments are widely used in the industry due to their ability measure steep high-slope surfaces. The focus method extracts areal surface map by analysing neighbouring pixels' contrast determine image position a stack of images. Traditional mechanically scan sample attaching objective lens piezoelectric actuator (PZT) for capture. slow mechanical movement PZT poses limitation fast modern advanced manufacturing applications. Additionally, PZTs' bulky mass size, nonlinear hysteresis motion other issues associated with scanning process. To address these limitations, we present chromatic approach that replaces wavelength mechanism. system employs determines axially shifting light source without any movement. This paper presents 30 µm step height using proposed system. results show capable measurements, but current version has low vertical resolution, which should be enhanced future versions.

Language: Английский

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