A Miniature Fibre-Optic Raman Probe Fabricated by Ultrafast Laser-Assisted Etching

Optical biopsy describes a range of medical procedures in which light is used to investigate disease in the body, often in hard-to-reach regions via optical fibres. Optical biopsies can reveal a multitude of diagnostic information to aid therapeutic diagnosis and treatment with higher specificity and shorter delay than traditional surgical techniques. One specific type of optical biopsy relies on Raman spectroscopy to differentiate tissue types at the molecular level and has been used successfully to stage cancer. However, complex micro-optical systems are usually needed at the distal end to optimise the signal-to-noise properties of the Raman signal collected. Manufacturing these devices, particularly in a way suitable for large scale adoption, remains a critical challenge. In this paper, we describe a novel fibre-fed micro-optic system designed for efficient signal delivery and collection during a Raman spectroscopy-based optical biopsy. Crucially, we fabricate the device using a direct-laser-writing technique known as ultrafast laser-assisted etching which is scalable and allows components to be aligned passively. The Raman probe has a sub-millimetre diameter and offers confocal signal collection with 71.3% ± 1.5% collection efficiency over a 0.8 numerical aperture. Proof of concept spectral measurements were performed on mouse intestinal tissue and compared with results obtained using a commercial Raman microscope.

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A Miniature Fibre-optic Raman Probe Fabricated by Ultrafast Laser Assisted Etching

10.20944/preprints202001.0351.v1 ◽

2020 ◽

Author(s):

Calum A. Ross ◽

David G. MacLachlan ◽

Brian Smith ◽

Rainer J. Beck ◽

Jonathan D. Shephard ◽

...

Keyword(s):

Raman Spectroscopy ◽

Collection Efficiency ◽

Surgical Techniques ◽

Numerical Aperture ◽

Ultrafast Laser ◽

The Body ◽

Optical Biopsy ◽

Optical Systems ◽

Direct Laser ◽

Raman Probe

Optical biopsy describes a range of medical procedures in which light is used to investigate disease in the body, often in hard-to-reach regions via optical fibres. Optical biopsies can reveal a multitude of diagnostic information to aid therapeutic diagnosis and treatment with higher specificity and shorter delay than traditional surgical techniques. One specific type of optical biopsy relies on Raman spectroscopy to differentiate tissue types at the molecular level and has been used successfully to stage cancer. However, complex micro-optical systems are usually needed at the distal-end to optimise the signal-to-noise properties of the Raman signal collected. Manufacturing these devices remains a critical challenge, particularly in a way suitable for large scale adoption. In this paper, we describe a novel fibre-fed micro-optic system designed for efficient signal delivery and collection during a Raman spectroscopy based optical biopsy. Crucially, we fabricate the device using a direct-laser-writing technique known as ultrafast laser assisted etching which is scalable and allows components to be aligned passively. The Raman probe has a sub-millimetre diameter and offers confocal signal collection with 71.3 ± 1.5% collection efficiency over a 0.8 numerical aperture. Proof of concept spectral measurements were performed on mouse intestinal tissue and compared with results obtained using a commercial Raman microscope.

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Manipulating and measuring single atoms in the Maltese cross geometry

Open Research Europe ◽

10.12688/openreseurope.13972.1 ◽

2021 ◽

Vol 1 ◽

pp. 102

Author(s):

Lorena C. Bianchet ◽

Natalia Alves ◽

Laura Zarraoa ◽

Natalia Bruno ◽

Morgan W. Mitchell

Keyword(s):

Collection Efficiency ◽

Coupling Efficiency ◽

Numerical Aperture ◽

Single Mode ◽

Optical Systems ◽

Single Atom ◽

Trapped Atoms ◽

Atom Trap ◽

Trap Axis ◽

Maltese Cross

Background: Optical microtraps at the focus of high numerical aperture (high-NA) imaging systems enable efficient collection, trapping, detection and manipulation of individual neutral atoms for quantum technology and studies of optical physics associated with super- and sub-radiant states. The recently developed “Maltese cross” geometry (MCG) atom trap uses four in-vacuum lenses to achieve four-directional high-NA optical coupling to single trapped atoms and small atomic arrays. This article presents the first extensive characterisation of atomic behaviour in a MCG atom trap. Methods: We employ a MCG system optimised for high coupling efficiency and characterise the resulting properties of the trap and trapped atoms. Using current best practices, we measure occupancy, loading rate, lifetime, temperature, fluorescence anti-bunching and trap frequencies. We also use the four-directional access to implement a new method to map the spatial distribution of collection efficiency from high-NA optics: we use the two on-trap-axis lenses to produce a 1D optical lattice, the sites of which are stochastically filled and emptied by the trap loading process. The two off-trap-axis lenses are used for imaging and single-mode collection. Correlations of single-mode and imaging fluorescence signals are then used to map the single-mode collection efficiency. Results: We observe trap characteristics comparable to what has been reported for single-atom traps with one- or two-lens optical systems. The collection efficiency distribution in the axial and transverse directions is directly observed to be in agreement with expected collection efficiency distribution from Gaussian beam optics. Conclusions: The multi-directional high-NA access provided by the Maltese cross geometry enables complex manipulations and measurements not possible in geometries with fewer directions of access, and can be achieved while preserving other trap characteristics such as lifetime, temperature, and trap size.

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Scientific aspect on Diet explained by Susrutha in Wound Healing

Journal of Ayurveda and Integrated Medical Sciences (JAIMS) ◽

10.21760/jaims.v2i05.10268 ◽

2017 ◽

Vol 2 (05) ◽

Author(s):

Manoj Kumar ◽

Amareshappa . ◽

Anjali Bharadwaj ◽

Shailaja S. V.

Keyword(s):

Wound Healing ◽

Mineral Metabolism ◽

Healing Process ◽

Surgical Techniques ◽

The Body ◽

Wound Healing Process ◽

Human Being ◽

Different Sources ◽

Scientific Aspect ◽

Important Branch

Wound healing has been the burning problem in a surgical practice because of a remarkable increase in the number of traumatic cases. A wound causes a number of changes in the body that can affect the healing process, including changes in energy, protein, carbohydrate, fat, vitamin and mineral metabolism. Various Ayurveda literatures, particularly, Sushruta Samhita, which is said to be an ancient textbook of surgery in Ayurveda, has mentioned about the diet for the person suffering from the wound, and the author said that diet plays a very important role in the wound healing process. Sushruta - The father of surgery has scientifically classified it in a systemic manner, whose wealth of clinical material and the principles of management are valid even today. Shalya Tantra (surgical branch in Ayurveda Science) is one of the important branch of Ayurveda, in which surgical and para-surgical techniques has described for management of various diseases. Vrana is the most important and widely described chapter of Shalya Tantra. Vrana (wound) is one of them, which have been managed by human being from starting of civilization. Under the circumstances, the first thing which the men came across was the injury from different sources which caused him the Vrana. Vrana is seen as debilitating and scaring disorder, usually seen affecting the human being at any age. Well balanced nutrition plays an essential role in the wound healing.

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Femtosecond-Laser Assisted Surgery of the Eye: Overview and Impact of the Low-Energy Concept

Micromachines ◽

10.3390/mi12020122 ◽

2021 ◽

Vol 12 (2) ◽

pp. 122

Author(s):

Catharina Latz ◽

Thomas Asshauer ◽

Christian Rathjen ◽

Alireza Mirshahi

Keyword(s):

Surgical Techniques ◽

Numerical Aperture ◽

Optical Breakdown ◽

Pulse Frequency ◽

Low Energy ◽

Human Cornea ◽

Energy Concept ◽

High Pulse Frequency ◽

Fs Laser ◽

High Pulse

This article provides an overview of both established and innovative applications of femtosecond (fs)-laser-assisted surgical techniques in ophthalmology. Fs-laser technology is unique because it allows cutting tissue at very high precision inside the eye. Fs lasers are mainly used for surgery of the human cornea and lens. New areas of application in ophthalmology are on the horizon. The latest improvement is the high pulse frequency, low-energy concept; by enlarging the numerical aperture of the focusing optics, the pulse energy threshold for optical breakdown decreases, and cutting with practically no side effects is enabled.

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In-Line Analysis of Diffusion Processes in Micro Channels by Long Distance Raman Photometric Measurement Technology—A Proof of Concept Study

Micromachines ◽

10.3390/mi12020116 ◽

2021 ◽

Vol 12 (2) ◽

pp. 116

Author(s):

Julian Deuerling ◽

Shaun Keck ◽

Inasya Moelyadi ◽

Jens-Uwe Repke ◽

Matthias Rädle

Keyword(s):

Numerical Aperture ◽

Spot Size ◽

Measuring System ◽

Optical Systems ◽

Measurement Technology ◽

Long Distance ◽

Measuring Point ◽

Acetone Concentration ◽

Micro Channels ◽

Set Up

This work presents a novel method for the non-invasive, in-line monitoring of mixing processes in microchannels using the Raman photometric technique. The measuring set-up distinguishes itself from other works in this field by utilizing recent state-of-the-art customized photon multiplier (CPM) detectors, bypassing the use of a spectrometer. This addresses the limiting factor of integration times by achieving measuring rates of 10 ms. The method was validated using the ternary system of toluene–water–acetone. The optical measuring system consists of two functional units: the coaxial Raman probe optimized for excitation at a laser wavelength of 532 nm and the photometric detector centered around the CPMs. The spot size of the focused laser is a defining factor of the spatial resolution of the set-up. The depth of focus is measured at approx. 85 µm with a spot size of approx. 45 µm, while still maintaining a relatively high numerical aperture of 0.42, the latter of which is also critical for coaxial detection of inelastically scattered photons. The working distance in this set-up is 20 mm. The microchannel is a T-junction mixer with a square cross section of 500 by 500 µm, a hydraulic diameter of 500 µm and 70 mm channel length. The extraction of acetone from toluene into water is tracked at an initial concentration of 25% as a function of flow rate and accordingly residence time. The investigated flow rates ranged from 0.1 mL/min to 0.006 mL/min. The residence times from the T-junction to the measuring point varies from 1.5 to 25 s. At 0.006 mL/min a constant acetone concentration of approx. 12.6% was measured, indicating that the mixing process reached the equilibrium of the system at approx. 12.5%. For prototype benchmarking, comparative measurements were carried out with a commercially available Raman spectrometer (RXN1, Kaiser Optical Systems, Ann Arbor, MI, USA). Count rates of the spectrophotometer surpassed those of the spectrometer by at least one order of magnitude at identical target concentrations and optical power output. The experimental data demonstrate the suitability and potential of the new measuring system to detect locally and time-resolved concentration profiles in moving fluids while avoiding external influence.

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1700 nm optical coherence microscopy enables minimally invasive, label-free, in vivo optical biopsy deep in the mouse brain

Light Science & Applications ◽

10.1038/s41377-021-00586-7 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Jun Zhu ◽

Hercules Rezende Freitas ◽

Izumi Maezawa ◽

Lee-way Jin ◽

Vivek J. Srinivasan

Keyword(s):

Minimally Invasive ◽

Mouse Brain ◽

Numerical Aperture ◽

Optical Biopsy ◽

Optical Coherence ◽

Label Free ◽

Optical Coherence Microscopy ◽

Minimal Invasiveness ◽

Cortical Regions

AbstractIn vivo, minimally invasive microscopy in deep cortical and sub-cortical regions of the mouse brain has been challenging. To address this challenge, we present an in vivo high numerical aperture optical coherence microscopy (OCM) approach that fully utilizes the water absorption window around 1700 nm, where ballistic attenuation in the brain is minimized. Key issues, including detector noise, excess light source noise, chromatic dispersion, and the resolution-speckle tradeoff, are analyzed and optimized. Imaging through a thinned-skull preparation that preserves intracranial space, we present volumetric imaging of cytoarchitecture and myeloarchitecture across the entire depth of the mouse neocortex, and some sub-cortical regions. In an Alzheimer’s disease model, we report that findings in superficial and deep cortical layers diverge, highlighting the importance of deep optical biopsy. Compared to other microscopic techniques, our 1700 nm OCM approach achieves a unique combination of intrinsic contrast, minimal invasiveness, and high resolution for deep brain imaging.

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Ultrawide-angle and high-efficiency metalens in hexagonal arrangement

Scientific Reports ◽

10.1038/s41598-020-72668-2 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Chun-Yuan Fan ◽

Chia-Ping Lin ◽

Guo-Dung J. Su

Keyword(s):

High Efficiency ◽

Numerical Aperture ◽

Vital Role ◽

Optical Systems ◽

Wide Field ◽

Wide Angle ◽

Camera Systems ◽

Single Lens ◽

Hexagonal Arrangement ◽

Virtual And Augmented Reality

Abstract Wide-angle optical systems play a vital role in imaging applications and have been researched for many years. In traditional lenses, attaining a wide field of view (FOV) by using a single optical component is difficult because these lenses have crucial aberrations. In this study, we developed a wide-angle metalens with a numerical aperture of 0.25 that provided a diffraction-limited FOV of over 170° for a wavelength of 532 nm without the need for image stitching or multiple lenses. The designed wide-angle metalens is free of aberration and polarization, and its full width of half maximum is close to the diffraction limit at all angles. Moreover, the metalens which is designed through a hexagonal arrangement exhibits higher focusing efficiency at all angles than most-seen square arrangement. The focusing efficiencies are as high as 82% at a normal incident and 45% at an incident of 85°. Compared with traditional optical components, the proposed metalens exhibits higher FOV and provides a more satisfactory image quality because of aberration correction. Because of the advantages of the proposed metalens, which are difficult to achieve for a traditional single lens, it has the potential to be applied in camera systems and virtual and augmented reality.

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Diagnosis and treatment of sacroiliac joint region pain in horses

UK-Vet Equine ◽

10.12968/ukve.2021.5.4.150 ◽

2021 ◽

Vol 5 (4) ◽

pp. 150-157

Author(s):

John David Stack ◽

Jessica Harley

Keyword(s):

Diagnostic Imaging ◽

Diagnostic Test ◽

Sacroiliac Joint ◽

Joint Pain ◽

Surgical Techniques ◽

The Body ◽

Anecdotal Evidence ◽

Joint Region ◽

Disease Treatment ◽

Presumptive Diagnosis

The sacroiliac joint and pain deriving from this complex region remains poorly understood in horses, although our understanding grows as the body of literature grows. A deeper understanding can be derived from the richer body of literature in human sacroiliac joint pain as the disease processes and biomechanics appear similar in both species. A highly specific and sensitive diagnostic test for this condition does not exist, so equine clinicians have to make presumptive diagnosis based on presenting signs, findings of clinical examination, diagnostic imaging and the response to blocking of the sacroiliac joint region. Many horses with sacroiliac joint region pain have concurrent orthopaedic injury or disease. Treatment is largely based on fundamentals, anecdotal evidence and translation of non-surgical techniques used in humans. Treatment for other orthopaedic conditions can conflict with rehabilitation for sacroiliac joint region pain, necessitating compromise.

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Electro-optic imaging enables efficient wide-field fluorescence lifetime microscopy

Nature Communications ◽

10.1038/s41467-019-12535-5 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 7

Author(s):

Adam J. Bowman ◽

Brannon B. Klopfer ◽

Thomas Juffmann ◽

Mark A. Kasevich

Keyword(s):

Temporal Resolution ◽

Single Molecule ◽

Fluorescence Lifetime ◽

Collection Efficiency ◽

Frame Rate ◽

Optical Systems ◽

Wide Field ◽

Pockels Cell ◽

Low Light ◽

Optical Efficiency

Abstract Nanosecond temporal resolution enables new methods for wide-field imaging like time-of-flight, gated detection, and fluorescence lifetime. The optical efficiency of existing approaches, however, presents challenges for low-light applications common to fluorescence microscopy and single-molecule imaging. We demonstrate the use of Pockels cells for wide-field image gating with nanosecond temporal resolution and high photon collection efficiency. Two temporal frames are obtained by combining a Pockels cell with a pair of polarizing beam-splitters. We show multi-label fluorescence lifetime imaging microscopy (FLIM), single-molecule lifetime spectroscopy, and fast single-frame FLIM at the camera frame rate with 103–105 times higher throughput than single photon counting. Finally, we demonstrate a space-to-time image multiplexer using a re-imaging optical cavity with a tilted mirror to extend the Pockels cell technique to multiple temporal frames. These methods enable nanosecond imaging with standard optical systems and sensors, opening a new temporal dimension for wide-field low-light microscopy.

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