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11 pages, 3516 KiB

Open AccessArticle

Intensity-Product-Based Optical Sensing to Beat the Diffraction Limit in an Interferometer

by Byoung S. Ham

Sensors 2024, 24(15), 5041; https://doi.org/10.3390/s24155041 - 4 Aug 2024

Cited by 2 | Viewed by 959

Abstract

The classically defined minimum uncertainty of the optical phase is known as the standard quantum limit or shot-noise limit (SNL), originating in the uncertainty principle of quantum mechanics. Based on the SNL, the phase sensitivity is inversely proportional to

\sqrt{K}

, where K [...] Read more.

The classically defined minimum uncertainty of the optical phase is known as the standard quantum limit or shot-noise limit (SNL), originating in the uncertainty principle of quantum mechanics. Based on the SNL, the phase sensitivity is inversely proportional to

\sqrt{K}

, where K is the number of interfering photons or statistically measured events. Thus, using a high-power laser is advantageous to enhance sensitivity due to the

\sqrt{K}

gain in the signal-to-noise ratio. In a typical interferometer, however, the resolution remains in the diffraction limit of the K = 1 case unless the interfering photons are resolved as in quantum sensing. Here, a projection measurement method in quantum sensing is adapted for classical sensing to achieve an additional

\sqrt{K}

gain in the resolution. To understand the projection measurements, several types of conventional interferometers based on N-wave interference are coherently analyzed as a classical reference and numerically compared with the proposed method. As a result, the Kth-order intensity product applied to the N-wave spectrometer exceeds the diffraction limit in classical sensing and the Heisenberg limit in quantum sensing, where the classical N-slit system inherently satisfies the Heisenberg limit of

π / N

in resolution. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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23 pages, 9419 KiB

Open AccessArticle

StarDICE II: Calibration of an Uncooled Infrared Thermal Camera for Atmospheric Gray Extinction Characterization

by Kélian Sommer, Bertrand Plez, Johann Cohen-Tanugi, Sylvie Dagoret-Campagne, Marc Moniez, Jérémy Neveu, Marc Betoule, Sébastien Bongard, Fabrice Feinstein, Laurent Le Guillou, Claire Juramy, Eduardo Sepulveda and Thierry Souverin

Sensors 2024, 24(14), 4498; https://doi.org/10.3390/s24144498 - 11 Jul 2024

Viewed by 1459

Abstract

The StarDICE experiment strives to establish an instrumental metrology chain with a targeted accuracy of 1 mmag in griz bandpasses to meet the calibration requirements of next-generation cosmological surveys. Atmospheric transmission is a significant source of systematic uncertainty. We propose a solution relying [...] Read more.

The StarDICE experiment strives to establish an instrumental metrology chain with a targeted accuracy of 1 mmag in griz bandpasses to meet the calibration requirements of next-generation cosmological surveys. Atmospheric transmission is a significant source of systematic uncertainty. We propose a solution relying on an uncooled infrared thermal camera to evaluate gray extinction variations. However, achieving accurate measurements with thermal imaging systems necessitates prior calibration due to temperature-induced effects, compromising their spatial and temporal precision. Moreover, these systems cannot provide scene radiance in physical units by default. This study introduces a new calibration process utilizing a tailored forward modeling approach. The method incorporates sensor, housing, flat-field support, and ambient temperatures, along with raw digital response, as input data. Experimental measurements were conducted inside a climatic chamber, with a FLIR Tau2 camera imaging a thermoregulated blackbody source. The results demonstrate the calibration effectiveness, achieving precise radiance measurements with a temporal pixel dispersion of 0.09

W m^{- 2} {sr}^{- 1}

and residual spatial noise of 0.03

W m^{- 2} {sr}^{- 1}

. We emphasize that the accuracy of scene radiance retrieval can be systematically affected by the camera’s close thermal environment, especially when the ambient temperature exceeds that of the scene. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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12 pages, 3293 KiB

Open AccessArticle

Live Cell Imaging by Single-Shot Common-Path Wide Field-of-View Reflective Digital Holographic Microscope

by Manoj Kumar, Takashi Murata and Osamu Matoba

Sensors 2024, 24(3), 720; https://doi.org/10.3390/s24030720 - 23 Jan 2024

Cited by 11 | Viewed by 2041

Abstract

Quantitative phase imaging by digital holographic microscopy (DHM) is a nondestructive and label-free technique that has been playing an indispensable role in the fields of science, technology, and biomedical imaging. The technique is competent in imaging and analyzing label-free living cells and investigating [...] Read more.

Quantitative phase imaging by digital holographic microscopy (DHM) is a nondestructive and label-free technique that has been playing an indispensable role in the fields of science, technology, and biomedical imaging. The technique is competent in imaging and analyzing label-free living cells and investigating reflective surfaces. Herein, we introduce a new configuration of a wide field-of-view single-shot common-path off-axis reflective DHM for the quantitative phase imaging of biological cells that leverages several advantages, including being less-vibration sensitive to external perturbations due to its common-path configuration, also being compact in size, simple in optical design, highly stable, and cost-effective. A detailed description of the proposed DHM system, including its optical design, working principle, and capability for phase imaging, is presented. The applications of the proposed system are demonstrated through quantitative phase imaging results obtained from the reflective surface (USAF resolution test target) as well as transparent samples (living plant cells). The proposed system could find its applications in the investigation of several biological specimens and the optical metrology of micro-surfaces. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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12 pages, 3108 KiB

Open AccessArticle

Deep Learning Approach for the Localization and Analysis of Surface Plasmon Scattering

by Jongha Lee, Gwiyeong Moon, Sukhyeon Ka, Kar-Ann Toh and Donghyun Kim

Sensors 2023, 23(19), 8100; https://doi.org/10.3390/s23198100 - 27 Sep 2023

Cited by 6 | Viewed by 1654

Abstract

Surface plasmon resonance microscopy (SPRM) combines the principles of traditional microscopy with the versatility of surface plasmons to develop label-free imaging methods. This paper describes a proof-of-principles approach based on deep learning that utilized the Y-Net convolutional neural network model to improve the [...] Read more.

Surface plasmon resonance microscopy (SPRM) combines the principles of traditional microscopy with the versatility of surface plasmons to develop label-free imaging methods. This paper describes a proof-of-principles approach based on deep learning that utilized the Y-Net convolutional neural network model to improve the detection and analysis methodology of SPRM. A machine-learning based image analysis technique was used to provide a method for the one-shot analysis of SPRM images to estimate scattering parameters such as the scatterer location. The method was assessed by applying the approach to SPRM images and reconstructing an image from the network output for comparison with the original image. The results showed that deep learning can localize scatterers and predict other variables of scattering objects with high accuracy in a noisy environment. The results also confirmed that with a larger field of view, deep learning can be used to improve traditional SPRM such that it localizes and produces scatterer characteristics in one shot, considerably increasing the detection capabilities of SPRM. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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14 pages, 3656 KiB

Open AccessArticle

“Grafting-To” Covalent Binding of Plasmonic Nanoparticles onto Silica WGM Microresonators: Mechanically Robust Single-Molecule Sensors and Determination of Activation Energies from Single-Particle Events

by Mariana P. Serrano, Sivaraman Subramanian, Catalina von Bilderling, Matías Rafti and Frank Vollmer

Sensors 2023, 23(7), 3455; https://doi.org/10.3390/s23073455 - 25 Mar 2023

Cited by 4 | Viewed by 2138

Abstract

We hereby present a novel “grafting-to”-like approach for the covalent attachment of plasmonic nanoparticles (PNPs) onto whispering gallery mode (WGM) silica microresonators. Mechanically stable optoplasmonic microresonators were employed for sensing single-particle and single-molecule interactions in real time, allowing for the differentiation between binding [...] Read more.

We hereby present a novel “grafting-to”-like approach for the covalent attachment of plasmonic nanoparticles (PNPs) onto whispering gallery mode (WGM) silica microresonators. Mechanically stable optoplasmonic microresonators were employed for sensing single-particle and single-molecule interactions in real time, allowing for the differentiation between binding and non-binding events. An approximated value of the activation energy for the silanization reaction occurring during the “grafting-to” approach was obtained using the Arrhenius equation; the results agree with available values from both bulk experiments and ab initio calculations. The “grafting-to” method combined with the functionalization of the plasmonic nanoparticle with appropriate receptors, such as single-stranded DNA, provides a robust platform for probing specific single-molecule interactions under biologically relevant conditions. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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Review

Jump to: Research, Other

14 pages, 3712 KiB

Open AccessReview

Ultrasound and Photoacoustic Imaging for the Guidance of Laser Ablation Procedures

by Samuel John, Yan Yan, Shirin Abbasi and Mohammad Mehrmohammadi

Sensors 2024, 24(11), 3542; https://doi.org/10.3390/s24113542 - 30 May 2024

Viewed by 1260

Abstract

The accuracy and efficacy of laser ablation procedures depend on the accurate placement of the laser applicator within the diseased tissue, monitoring the real-time temperature during the ablation procedure, and mapping the extent of the ablated region. Ultrasound (US) imaging has been widely [...] Read more.

The accuracy and efficacy of laser ablation procedures depend on the accurate placement of the laser applicator within the diseased tissue, monitoring the real-time temperature during the ablation procedure, and mapping the extent of the ablated region. Ultrasound (US) imaging has been widely used to guide ablation procedures. While US imaging offers significant advantages for guiding ablation procedures, its limitations include low imaging contrast, angular dependency, and limited ability to monitor the temperature. Photoacoustic (PA) imaging is a relatively new imaging modality that inherits the advantages of US imaging and offers enhanced capabilities for laser-guided ablations, such as accurate, angle-independent tracking of ablation catheters, the potential for quantitative thermometry, and monitoring thermal lesion formation. This work provides an overview of ultrasound-guided procedures and how different US-related artifacts limit their utility, followed by introducing PA as complementary to US as a solution to address the existing limitations and improve ablation outcomes. Furthermore, we highlight the integration of PA-driven features into existing US-guided laser ablation systems, along with their limitations and future outlooks. Integrated US/PA-guided laser ablation procedures can lead to safer and more precise treatment outcomes. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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22 pages, 1996 KiB

Open AccessReview

Diffuse Correlation Spectroscopy: A Review of Recent Advances in Parallelisation and Depth Discrimination Techniques

by Edward James and Peter R. T. Munro

Sensors 2023, 23(23), 9338; https://doi.org/10.3390/s23239338 - 22 Nov 2023

Cited by 7 | Viewed by 3595

Abstract

Diffuse correlation spectroscopy is a non-invasive optical modality used to measure cerebral blood flow in real time, and it has important potential applications in clinical monitoring and neuroscience. As such, many research groups have recently been investigating methods to improve the signal-to-noise ratio, [...] Read more.

Diffuse correlation spectroscopy is a non-invasive optical modality used to measure cerebral blood flow in real time, and it has important potential applications in clinical monitoring and neuroscience. As such, many research groups have recently been investigating methods to improve the signal-to-noise ratio, imaging depth, and spatial resolution of diffuse correlation spectroscopy. Such methods have included multispeckle, long wavelength, interferometric, depth discrimination, time-of-flight resolution, and acousto-optic detection strategies. In this review, we exhaustively appraise this plethora of recent advances, which can be used to assess limitations and guide innovation for future implementations of diffuse correlation spectroscopy that will harness technological improvements in the years to come. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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Other

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14 pages, 3427 KiB

Open AccessPerspective

Chewing Analysis by Means of Electromagnetic Articulography: Current Developments and New Possibilities

by Franco Marinelli, Camila Venegas, Josefa Alarcón, Pablo Navarro and Ramón Fuentes

Sensors 2023, 23(23), 9511; https://doi.org/10.3390/s23239511 - 30 Nov 2023

Viewed by 1872

Abstract

Chewing is a complex procedure that involves sensory feedback and motor impulses controlled by the trigeminal system in the brainstem. The analysis of mandibular movement is a first approximation to understanding these mechanisms. Several recording methods have been tested to achieve this. Video, [...] Read more.

Chewing is a complex procedure that involves sensory feedback and motor impulses controlled by the trigeminal system in the brainstem. The analysis of mandibular movement is a first approximation to understanding these mechanisms. Several recording methods have been tested to achieve this. Video, ultrasound, the use of external markers and kinesiographs are examples of recording systems used in research. Electromagnetic articulography is an alternative method to those previously mentioned. It consists of the use of electromagnetic fields and receiver coils. The receiver coils are placed on the points of interest and the 3D coordinates of movement are saved in binary files. In the Oral Physiology Laboratory of the Dental Sciences Research Center (Centro de Investigación en Ciencias Odontológicas—CICO), in the Faculty of Dentistry at the Universidad de La Frontera (Temuco, Chile) several research studies have been carried out using the AG501 3D EMA articulograph (Carstens Medizinelektronik, Lenglern, Germany). With this device, they developed a series of protocols to record mandibular movement and obtain new information, such as the 3D Posselt polygon, the area of each polygon, individualized masticatory cycles and speed and acceleration profiles. Other investigations have analyzed these parameters, but separately. The AG501 allows for holistic analysis of all these data without altering natural movement. A limitation of this technology is the interference generated by its metallic elements. The aim of the present work is to show the developed methods used to record mandibular movement in the CICO, using the AG501 and compare them with others used in several research studies. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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6 pages, 1620 KiB

Open AccessBrief Report

Automatic Alignment Method for Controlled Free-Space Excitation of Whispering-Gallery Resonances

by Davide D’Ambrosio, Marialuisa Capezzuto, Antonio Giorgini, Pietro Malara, Saverio Avino and Gianluca Gagliardi

Sensors 2023, 23(21), 9007; https://doi.org/10.3390/s23219007 - 6 Nov 2023

Cited by 1 | Viewed by 1170

Abstract

Whispering-gallery mode microresonators have gained wide popularity as experimental platforms for different applications, ranging from biosensing to nonlinear optics. Typically, the resonant modes of dielectric microresonators are stimulated via evanescent wave coupling, facilitated using tapered optical fibers or coupling prisms. However, this method [...] Read more.

Whispering-gallery mode microresonators have gained wide popularity as experimental platforms for different applications, ranging from biosensing to nonlinear optics. Typically, the resonant modes of dielectric microresonators are stimulated via evanescent wave coupling, facilitated using tapered optical fibers or coupling prisms. However, this method poses serious shortcomings due to fabrication and access-related limitations, which could be elegantly overcome by implementing a free-space coupling approach; although additional alignment procedures are needed in this case. To address this issue, we have developed a new algorithm to excite the microresonator automatically. Here, we show the working mechanism and the preliminary results of our experimental method applied to a home-made silica microsphere, using a visible laser beam with a spatial light modulator and a software control. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Advanced Sensing and Imaging Technologies)

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