Scientific Camera Research Articles

A Guide to Build a Highly Inclined Swept Tile Microscope for Extended Field-of-view Single-molecule Imaging.

Single-molecule imaging has greatly advanced our understanding of molecular mechanisms in biological studies. However, it has been challenging to obtain large field-of-view, high-contrast images in thick cells and tissues. Here, we introduce highly inclined swept tile (HIST) microscopy that overcomes this problem. A pair of cylindrical lenses was implemented to generate an elongated excitation beam that was scanned over a large imaging area via a fast galvo mirror. A 4f configuration was used to position optical components. A scientific complementary metal-oxide semiconductor camera detected the fluorescence signal and blocked the out-of-focus background with a dynamic confocal slit synchronized with the beam sweeping. We present a step-by-step instruction on building the HIST microscope with all basic components.

Measuring Ocular Aberrations Sequentially Using a Digital Micromirror Device.

The Hartmann–Shack wavefront sensor is widely used to measure aberrations in both astronomy and ophthalmology. Yet, the dynamic range of the sensor is limited by cross-talk between adjacent lenslets. In this study, we explore ocular aberration measurements with a recently-proposed variant of the sensor that makes use of a digital micromirror device for sequential aperture scanning of the pupil, thereby avoiding the use of a lenslet array. We report on results with the sensor using two different detectors, a lateral position sensor and a charge-coupled device (CCD) scientific camera, and explore the pros and cons of both. Wavefront measurements of a highly aberrated artificial eye and of five real eyes, including a highly myopic subject, are demonstrated, and the role of pupil sampling density, CCD pixel binning, and scanning speed are explored. We find that the lateral position sensor is mostly suited for high-power applications, whereas the CCD camera with pixel binning performs consistently well both with the artificial eye and for real-eye measurements, and can outperform a commonly-used wavefront sensor with highly aberrated wavefronts.

Wide-Field Planar Magnetic Imaging Using Spins in Diamond

The nitrogen-vacancy color centers in diamond can be used as an excellent magnetic sensor. In this work, we present a wide-field planar magnetic imaging technique based on nitrogen-vacancy color centers. Through optically detected magnetic resonance (ODMR) which is readout from a scientific CMOS camera to extract resonance frequency, we experimentally reconstruct the magnetic field distribution of permanent magnets and particles of magnetite (Fe3O4). Moreover, by using this method we imagined the magnetic field distribution of one integrated cell heater widely used in temperature control with magnetic field suppression. And the experiment shows that this technique can be applied in engineering. The imaging field of this technology can reach the sub-millimeter level and the spatial resolution can reach the optical diffraction limit. The presented wide-field NV imaging technique offers wide-field imaging, high spatial resolution, and high magnetic sensitivity.

Automatic Detection and Tracking of Plumes from 67P/Churyumov–Gerasimenko in Rosetta/OSIRIS Image Sequences

Abstract Solar system bodies such as comets and asteroids are known to eject material from their surface in the form of jets and plumes. Observations of these transient outbursts can offer insight into the inner workings and makeup of their originating body. However, the detection of and response to these events has thus far been manually controlled by ground operations, limiting the response time, due to the light time delay of ground communications. For distant bodies, the delay can exceed the duration of temporary events, making it impossible to respond with follow-up observations. To address this need, we developed a computer vision methodology for detecting plumes of the comet 67P/Churyumov–Gerasimenko from imagery acquired by the OSIRIS scientific camera system. While methods exist for the automatic detection of plumes on spherical and near-convex solar system bodies, this is the first work that addresses the case of highly irregularly shaped bodies such as 67P/Churyumov–Gerasimenko. Our work is divided into two distinct components: an image processing pipeline that refines a model-based estimate of the nucleus body, and an iterative plume detection algorithm that finds regions of local intensity maxima and joins plume segments across successively higher altitudes. Finally, we validate this method by comparing automatically labeled images to those labeled by hand, and find no significant differences in variability. This technique has utility in both ground-based analysis of plume sequences as well as onboard applications, such as isolating short sequences of high activity for priority downloading or triggering follow-up observations with additional instruments.

Performance comparison of state-of-the-art high-speed video cameras for scientific applications

Time-resolved visualization of fast processes using high-speed digital video-cameras has been widely used in most fields of scientific research for over a decade. In many applications, high-speed imaging is used not only to record the time history of a phenomenon but also to quantify it, hence requiring dependable equipment. Important aspects of two-dimensional imaging instrumentation used to qualitatively or quantitatively assess fast-moving scenes include sensitivity, linearity, as well as signal-to-noise ratio (SNR). Under certain circumstances, the weaknesses of commercially available high-speed cameras, i.e., sensitivity, linearity, image lag, etc., render the experiment complicated and uncertain. Our study evaluated two advanced CMOS-based, continuous-recording, high-speed cameras available at the moment of writing. Various parameters, potentially important toward accurate time-resolved measurements and photonic quantification, have been measured under controlled conditions on the bench, using scientific instrumentation. Testing procedures to measure sensitivity, linearity, SNR, shutter accuracy, and image lag are proposed and detailed. The results of the tests, comparing the two high-speed cameras under study, are also presented and discussed. Results show that, with careful implementation and understanding of their performance and limitations, these high-speed cameras are reasonable alternatives to scientific CCD cameras, while also delivering time-resolved imaging data.

Fast High-Energy X-Ray Imaging for Severe Accidents Experiments on the Future PLINIUS-2 Platform

The future PLINIUS-2 platform of the Commissariat a l’Energie Atomique (CEA) of Cadarache will be dedicated to the study of corium interactions in severe nuclear accidents, and will host innovative large-scale experiments. The nuclear measurement laboratory of CEA Cadarache is in charge of real-time high-energy X-ray imaging setups, for the study of the corium–water and corium–sodium interaction, and of the corium stratification process. Imaging such large and high-density objects requires a 15 MeV linear electron accelerator coupled to a tungsten target creating a high-energy bremsstrahlung X-ray flux, with corresponding dose rate about 100 Gy/min at 1 m. The signal is detected by phosphor screens coupled to high-framerate scientific CMOS cameras. The imaging setup is established using an experimentally validated home-made simulation software High-Energy MODeling for RAdiography and TOmography (MODHERATO). The code computes quantitative radiographic signals from the description of the source, object geometry and composition, detector, and geometrical configuration (magnification factor, etc.). It accounts for several noise sources (photonic and electronic noises, and swank and readout noise), and for image blur due to the source spot-size and to the detector unsharpness. In a view to PLINIUS-2, the simulation has been improved to account for the scattered flux, which is expected to be significant. This paper presents the scattered flux calculation using the Monte-Carlo N-particle transport code, and its integration into the MODHERATO simulation. Then, the validation of the improved simulation is presented, through confrontation to real measurement images taken on a small-scale equivalent setup on the PLINIUS platform. Excellent agreement is achieved. This improved simulation is therefore being used to design the PLINIUS-2 imaging setups (source, detectors, and cameras). Simulation will be presented for different configurations, as well as preliminary tests of alternative detectors considered for PLINIUS-2.

Identification of heavy ions by imaging individual particle tracks in CF4-filled gas scintillation detectors

We propose a novel method for identification of heavy charged particles, based on the principle that the distance between the Bragg peak position and the terminal position (Dpt) of an energetic ion track varies with the specie of the heavy charged particle. Online measurements can be achieved by imaging individual particle tracks in CF4-filled gas scintillation detectors using a real-time scientific camera. By calculating the integration of the image intensity along the recorded track, experimental Bragg curves can be obtained and then Dpt values can be extracted promptly. Proof-of-principle experiments have been performed with 6.30 MeV 1H, 5.49 MeV 4He, and 46.50 MeV 7Li ions. A number of clear individual ion tracks were imaged and analyzed, with the satisfactory results that both the type and energy of each ions were identified precisely, demonstrating good identification capability of the proposed method. Therefore, this study is of particularly importance not only in methodology but also in practical for online identification of heavy charged particles in many fields such as space radiation detection and nuclear reaction diagnostic experiments.

Lightweight sCMOS-based high-density diffuse optical tomography.

.Though optical imaging of human brain function is gaining momentum, widespread adoption is restricted in part by a tradeoff among cap wearability, field of view, and resolution. To increase coverage while maintaining functional magnetic resonance imaging (fMRI)-comparable image quality, optical systems require more fibers. However, these modifications drastically reduce the wearability of the imaging cap. The primary obstacle to optimizing wearability is cap weight, which is largely determined by fiber diameter. Smaller fibers collect less light and lead to challenges in obtaining adequate signal-to-noise ratio. Here, we report on a design that leverages the exquisite sensitivity of scientific CMOS cameras to use fibers with smaller cross-sectional area than current high-density diffuse optical tomography (HD-DOT) systems. This superpixel sCMOS DOT (SP-DOT) system uses -diameter fibers that facilitate a lightweight, wearable cap. We developed a superpixel algorithm with pixel binning and electronic noise subtraction to provide high dynamic range (), high frame rate (), and a low effective detectivity threshold (), each comparable with previous HD-DOT systems. To assess system performance, we present retinotopic mapping of the visual cortex ( subjects). SP-DOT offers a practical solution to providing a wearable, large field-of-view, and high-resolution optical neuroimaging system.

Temporal multiplexing of the scientific grade camera for hyper-frame-rate imaging.

In order to maximize the spatio-temporal resolution of the scientific grade camera at width-limited ROI, this paper proposes a new hyper-frame-rate imaging method by temporal multiplexing the sub-region of the image sensor. In the system, a dual-axis scanning galvanometer is localized at the relay pupil plane and a high quality scan lens is utilized to form an image-side telecentric path. Following this path can overcome bandwidth waste in the conventional exposure and readout mode, and maintain other performances of image sensors. As a result, the sCMOS camera has performed 432fps over 820 × 700 pixel arrays to record the dynamic heartbeat of zebrafish larvae.

Experimental validation of joint phase and amplitude wave-front sensing with coronagraphic phase diversity for high-contrast imaging

Context. The next generation of space-borne instruments dedicated to the direct detection of exoplanets requires unprecedented levels of wavefront control precision. Coronagraphic wavefront sensing techniques for these instruments must measure both the phase and amplitude of the optical aberrations using the scientific camera as a wavefront sensor. Aims. In this paper, we develop an extension of coronagraphic phase diversity to the estimation of the complex electric field, that is, the joint estimation of phase and amplitude. Methods. We introduced the formalism for complex coronagraphic phase diversity. We have demonstrated experimentally on the Très Haute Dynamique testbed at the Observatoire de Paris that it is possible to reconstruct phase and amplitude aberrations with a subnanometric precision using coronagraphic phase diversity. Finally, we have performed the first comparison between the complex wavefront estimated using coronagraphic phase diversity (which relies on time-modulation of the speckle pattern) and the one reconstructed by the self-coherent camera (which relies on the spatial modulation of the speckle pattern). Results. We demonstrate that coronagraphic phase diversity retrieves complex wavefront with subnanometric precision with a good agreement with the reconstruction performed using the self-coherent camera. Conclusions. This result paves the way to coronagraphic phase diversity as a coronagraphic wave-front sensor candidate for very high contrast space missions.

Determination of fast neutron spectrum using recoil-proton track imaging method

High sensitivity and good neutron/gamma discrimination, as well as online determination, are goals that researchers are pursuing for fast neutron spectrum measurements (FNSM). For this purpose, we are attempting a novel approach based on the recoil-proton track imaging (RPTI) method to do FNSM. The RPTI neutron spectrometer has been designed and built, and it mainly consists of a polyethylene foil for converting neutrons to protons, a gas scintillation chamber for generating photons along the recoil proton track, and a scientific camera system for recording the track photons in real time. Proof-of-principle experiments have been performed with the RPTI neutron spectrometer at a DT neutron generator at China Institute of Atomic Energy. As a result, numerous recoil proton track images at the single-particle level were successfully acquired and revealed in real time. Also, the proton tracks can be clearly distinguished from the background in the track images, indicating good signal-to-background ratio of the system. Particularly, both the proton ranges and the Bragg curve peak positions can be extracted online from the track images, which can lead to online generation of DT neutron spectra. These results show promising performance of the novel fast neutron spectrometer, which will bring significant advantages in various applications.

Studies of an X-ray imaging detector based on THGEM and CCD camera

The photons generated by the electron avalanche in gaseous detectors are known as the secondary scintillation light, of which the spectrum range is from ultraviolet to visible. So it is possible to collect directly the avalanche-induced photons in visible range by light sensors, such as charged-couple device (CCD). The optical readout is a new method for 2-D imaging of high spatial resolution based on the micro-pattern gaseous detectors (MPGDs). The traditional charge readout method for the MPGDs is complicated, expensive, and strongly depends on the technology of application-specific integrated circuit. In some cases, for example, low-frame-rate 2-D imaging, the optical readout has more advantages, such as simple, cheap and easy to use. Therefore, a gaseous detector was developed based on the thick gaseous electron multiplier (THGEM) and the ordinary scientific CCD camera as readout to realize the X-ray imaging instead of charge readout. The THGEMs with $$60\times 60\,\hbox {mm}^2$$ sensitive area were developed to reach high gain, and the $$\hbox {Ar} + \hbox {CF}_4$$ gas mixture was chosen for strong light emission. And so a general scientific CCD can be used for readout and replacing the intensified CCD, which is more expensive than general CCD. Some clear X-ray images were obtained by this optical readout THGEM detector, and the spatial resolution achieved is $$275\,\upmu \hbox {m}$$ . It is indicated that this kind of detectors have promising imaging capability and great potential for practical application.

On-rail solution for autonomous inspections in electrical substations

This work presents an alternative solution for autonomous inspections in electrical substations. The autonomous system is a robot that moves on rails, collects infrared and visible images of selected targets, also processes the data and predicts the components lifetime. The robot moves on rails to overcome difficulties found in not paved substations commonly encountered in Brazil. We take advantage of using rails to convey the data by them, minimizing the electromagnetic interference, and at the same time transmitting electrical energy to feed the autonomous system. As part of the quality control process, we compared thermographic inspections made by the robot with inspections made by a trained thermographer using a scientific camera Flir® SC660. The results have shown that the robot achieved satisfactory results, identifying components and measuring temperature accurately. The embodied routine considers the weather changes along the day, providing a standard result of the components thermal response, also gives the uncertainty of temperature measurement, contributing to the quality in the decision making process.

Multiplane and Spectrally-Resolved Single Molecule Localization Microscopy with Industrial Grade CMOS cameras

This work explores the use of industrial grade CMOS cameras for single molecule localization microscopy (SMLM). We show that industrial grade CMOS cameras approach the performance of scientific grade CMOS cameras at a fraction of the cost. This makes it more economically feasible to construct high-performance imaging systems with multiple cameras that are capable of a diversity of applications. In particular we demonstrate the use of industrial CMOS cameras for biplane, multiplane and spectrally resolved SMLM. We also provide open-source software for simultaneous control of multiple CMOS cameras and for the reduction of the movies that are acquired to super-resolution images.

Fast high-energy X-ray imaging for Severe Accidents experiments on the future PLINIUS-2 platform

The future PLINIUS-2 platform of CEA Cadarache will be dedicated to the study of corium interactions in severe nuclear accidents, and will host innovative large-scale experiments. The Nuclear Measurement Laboratory of CEA Cadarache is in charge of real-time high-energy X-ray imaging set-ups, for the study of the corium-water and corium-sodium interaction, and of the corium stratification process. Imaging such large and high-density objects requires a 15 MeV linear electron accelerator coupled to a tungsten target creating a high-energy Bremsstrahlung X-ray flux, with corresponding dose rate about 100 Gy/min at 1 m. The signal is detected by phosphor screens coupled to high-framerate scientific CMOS cameras. The imaging set-up is established using an experimentally-validated home-made simulation software (MODHERATO). The code computes quantitative radiographic signals from the description of the source, object geometry and composition, detector, and geometrical configuration (magnification factor, etc.). It accounts for several noise sources (photonic and electronic noises, swank and readout noise), and for image blur due to the source spot-size and to the detector unsharpness. In a view to PLINIUS-2, the simulation has been improved to account for the scattered flux, which is expected to be significant. The paper presents the scattered flux calculation using the MCNP transport code, and its integration into the MODHERATO simulation. Then the validation of the improved simulation is presented, through confrontation to real measurement images taken on a small-scale equivalent set-up on the PLINIUS platform. Excellent agreement is achieved. This improved simulation is therefore being used to design the PLINIUS-2 imaging set-ups (source, detectors, cameras, etc.).

Shore-based monitoring of flow dynamics in a steep bedrock canyon river

The pace of landscape evolution is set by bedrock erosion in canyons. This phenomenon occurs by various geological processes including plucking of bedrock blocks and abrasion by saltating bedload and suspended load in highly turbulent flows. For a better understanding of the river flow characteristics in bedrock rivers, a comprehensive study of flow dynamics was undertaken in Black Canyon in the Fraser River, British Columbia. We used shore-based video imagery of the river to study surface flow dynamics. The shore-based monitoring system consisted of a Campbell Scientific camera mounted at the top of the canyon walls. We monitored the water surface boils due to upwelling and determined river surface flow velocities from the shore-based imagery. Automatic detection of the upwelling surface boils leads to a better understanding of the secondary circulation patterns and flow structures in this large steep river bedrock canyon. The data collection and analytical procedures developed in this research are cost-effective tools for remotely determining flow dynamics, which can be applied to other rivers.

Visualization of grid-generated turbulence in He II using PTV

Due to its low viscosity, cryogenic He II has potential use for simulating large-scale, high Reynolds number turbulent flow in a compact and efficient apparatus. To realize this potential, the behavior of the fluid in the simplest cases, such as turbulence generated by flow past a mesh grid, must be well understood. We have designed, constructed, and commissioned an apparatus to visualize the evolution of turbulence in the wake of a mesh grid towed through He II. Visualization is accomplished using the particle tracking velocimetry (PTV) technique, where μm-sized tracer particles are introduced to the flow, illuminated with a planar laser sheet, and recorded by a scientific imaging camera; the particles move with the fluid, and tracking their motion with a computer algorithm results in a complete map of the turbulent velocity field in the imaging region. In our experiment, this region is inside a carefully designed He II filled cast acrylic channel measuring approximately 16 × 16 × 330 mm. One of three different grids, which have mesh numbers M = 3, 3.75, or 5 mm, can be attached to the pulling system which moves it through the channel with constant velocity up to 600 mm/s. The consequent motion of the solidified deuterium tracer particles is used to investigate the energy statistics, effective kinematic viscosity, and quantized vortex dynamics in turbulent He II.

Surface thermography using dual channel imaging based on the blue and red emission of Ba3MgSi2O8:Eu2+, Mn2+

In this investigation, we present a surface temperature determination method based on the luminescence characteristics of Ba3MgSi2O8:Eu2+, Mn2+. Simple optics utilizing only one RGB scientific CMOS camera makes this measurement technique easily applicable. Four different imaging methods were developed and are presented together with the corresponding calibration curves. We successfully utilized the methods to take a surface temperature distribution image on glass plates with a point heat source between them.

Wide-field spectrally resolved quantitative fluorescence imaging system: toward neurosurgical guidance in glioma resection.

In high-grade glioma surgery, tumor resection is often guided by intraoperative fluorescence imaging. 5-aminolevulinic acid-induced protoporphyrin IX (PpIX) provides fluorescent contrast between normal brain tissue and glioma tissue, thus achieving improved tumor delineation and prolonged patient survival compared with conventional white-light-guided resection. However, commercially available fluorescence imaging systems rely solely on visual assessment of fluorescence patterns by the surgeon, which makes the resection more subjective than necessary. We developed a wide-field spectrally resolved fluorescence imaging system utilizing a Generation II scientific CMOS camera and an improved computational model for the precise reconstruction of the PpIX concentration map. In our model, the tissue’s optical properties and illumination geometry, which distort the fluorescent emission spectra, are considered. We demonstrate that the CMOS-based system can detect low PpIX concentration at short camera exposure times, while providing high-pixel resolution wide-field images. We show that total variation regularization improves the contrast-to-noise ratio of the reconstructed quantitative concentration map by approximately twofold. Quantitative comparison between the estimated PpIX concentration and tumor histopathology was also investigated to further evaluate the system.

Characterization of an industry-grade CMOS camera well suited for single molecule localization microscopy \u2013 high performance super-resolution at low cost

Many commercial as well as custom-built fluorescence microscopes use scientific-grade cameras that represent a substantial share of the instrument’s cost. This holds particularly true for super-resolution localization microscopy where high demands are placed especially on the detector with respect to sensitivity, noise, and also image acquisition speed. Here, we present and carefully characterize an industry-grade CMOS camera as a cost-efficient alternative to commonly used scientific cameras. Direct experimental comparison of these two detector types shows widely similar performance for imaging by single molecule localization microscopy (SMLM). Furthermore, high image acquisition speeds are demonstrated for the CMOS detector by ultra-fast SMLM imaging.