The SKED: speckle knife edge detector

Sharpies, S. D.; Light, Roger; Achamfuo-Yeboah, Samuel; Clark, Matt; Somekh, Michael Geoffrey

doi:10.1088/1742-6596/520/1/012004

Cited by 16 publications

(8 citation statements)

References 5 publications

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“…A previously reported detector developed by the authors, known as the speckle knife edge detector (SKED) [28,29], has been implemented as an all-electronic chip based device. As a concept, the SKED works as an expanded knife edge detector-in place of the two adjacent photodiodes there is an array of photodiodes.…”

Section: Speckle Knife Edge Detectormentioning

confidence: 99%

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

et al. 2018

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Additive manufacturing (AM) is a production technology where material is accumulated to create a structure, often through added shaped layers. The major advantage of additive manufacturing is in creating unique and complex parts for use in areas where conventional manufacturing reaches its limitations. However, the current class of AM systems produce parts that contain structural defects (e.g., cracks and pores) which is not compatible with certification in high value industries. The probable complexity of an AM design increases the difficulty of using many non-destructive evaluation (NDE) techniques to inspect AM parts—however, a unique opportunity exists to interrogate a part during production using a rapid surface based technique. Spatially resolved acoustic spectroscopy (SRAS) is a laser ultrasound inspection technique used to image material microstructure of metals and alloys. SRAS generates and detects `controlled’ surface acoustic waves (SAWs) using lasers, which makes it a non-contact and non-destructive technique. The technique is also sensitive to surface and subsurface voids. Work until now has been on imaging the texture information of selective laser melted (SLM) parts once prepared (i.e., polished with R a < 0 . 1 μ m)—the challenge for performing laser ultrasonics in-process is measuring waves on the rough surfaces present on as-deposited parts. This paper presents the results of a prototype SRAS system, developed using the rough surface ultrasound detector known as speckle knife edge detector (SKED)—texture images using this setup of an as-deposited Ti64 SLM sample, with a surface roughness of S a ≈ 6 μ m, were obtained.

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Section: Speckle Knife Edge Detectormentioning

confidence: 99%

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

et al. 2018

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“…This is at high scan rates of 1000 points per second and without the need to section all samples due to larger size constraints, although the spatial resolution is inferior to EBSD (several nm) and currently SRAS samples must be polished smooth (Mark et al, 2017). Although the capability of the current class of equipment is limited by sample roughness, techniques to circumvent this issue are under investigation (Sharples et al, 2014). The lower spatial resolution of SRAS is due to restrictions on the size of the generation patch that can be used, a smaller patch gives in better resolution but results in greater laser intensity which can lead to burning of the sample (Smith et al, 2014).…”

Section: Ultrasonic Techniquesmentioning

confidence: 99%

Destructive and non-destructive testing methods for characterization and detection of machining-induced white layer: A review paper

Brown

Wright

M’Saoubi³

et al. 2018

CIRP Journal of Manufacturing Science and Technology

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The presence of machining-induced white layer in the near-surface of critical aeroengine alloys has a detrimental effect on the lifetime of a component. Present techniques for identifying and characterizing white layer, such as optical microscopy and hardness testing, whilst effective, are destructive, costly and time-consuming. Non-destructive testing methods may, therefore, offer improvements to the process of white layer detection. This paper discusses the formation mechanisms and the defining physical properties of machininginduced white layers before offering a comprehensive review of the current state-of-the-art in both destructive and non-destructive testing methods for detecting this anomalous surface feature.

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“…There are also non-interferometric approaches for remote acoustic signal detection. Clark et al detected surface acoustic waves by tracking the movement of multiple speckles using simple diode detection systems [ 12 , 13 ]. For this approach, however, the speckles are imaged in the near-field, and thus, Fresnel diffraction applies.…”

Section: Introductionmentioning

confidence: 99%

Remote Photoacoustic Sensing Using Single Speckle Analysis by an Ultra-Fast Four Quadrant Photo-Detector

Lengenfelder¹,

Hohmann²,

Späth³

et al. 2021

Sensors

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The need for tissue contact makes photoacoustic imaging not applicable for special medical applications like wound imaging, endoscopy, or laser surgery. An easy, stable, and contact-free sensing technique might thus help to broaden the applications of the medical imaging modality. In this work, it is demonstrated for the first time that remote photoacoustic sensing by speckle analysis can be performed in the MHz sampling range by tracking a single speckle using a four quadrant photo-detector. A single speckle, which is created by self-interference of surface back-reflection, is temporally analyzed using this photo-detector. Phantoms and skin samples are measured in transmission and reflection mode. The potential for miniaturization for endoscopic application is demonstrated by fiber bundle measurements. In addition, sensing parameters are discussed. Photoacoustic sensing in the MHz sampling range by single speckle analysis with the four quadrant detector is successfully demonstrated. Furthermore, the endoscopic applicability is proven, and the sensing parameters are convenient for photoacoustic sensing. It can be concluded that a single speckle contains all the relevant information for remote photoacoustic signal detection. Single speckle sensing is therefore an easy, robust, contact-free photoacoustic detection technique and holds the potential for economical, ultra-fast photoacoustic sensing. The new detection technique might thus help to broaden the field of photoacoustic imaging applications in the future.

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The SKED: speckle knife edge detector

Cited by 16 publications

References 5 publications

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

Imaging Material Texture of As-Deposited Selective Laser Melted Parts Using Spatially Resolved Acoustic Spectroscopy

Destructive and non-destructive testing methods for characterization and detection of machining-induced white layer: A review paper

Remote Photoacoustic Sensing Using Single Speckle Analysis by an Ultra-Fast Four Quadrant Photo-Detector

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