A Low Cost Silicon Based Thermal Camera for Volcanic Applications

2021 ◽  
Author(s):  
Joshua Marks ◽  
Jonas Kuhn ◽  
Christopher Fuchs ◽  
Nicole Bobrowski ◽  
Ulrich Platt
Keyword(s):  
Spatial Resolution ◽  
Near Infrared ◽  
Low Cost ◽  
Digital Camera ◽  
Visible Spectrum ◽  
Sensitivity Study ◽  
Volcanic Gas ◽  
Infrared Wavelength ◽  
Volcanic Emission ◽  
Silicon Based

<p class="western" lang="en-GB" align="justify">Volcanic gases and the chemical reactions inside volcanic emission plumes are of great interest because of their impact on atmospheric processes and climate. The evolution of many volcanic gas compounds is most likely strongly dependent on the general physical conditions during the emission processes. Particularly, the knowledge about the temperature of the lava, i.e. the origin of the gases, is crucial.</p> <p class="western" lang="en-GB" align="justify">Commercially available thermal cameras for the relevant temperature range (ca. 600-1200 °C) are still rather expensive, bulky, and have a limited spatial resolution.</p> <p class="western" lang="en-GB" align="justify">We present an approach to use a compact (‘point and shoot’) consumer digital camera with a silicon based detector as a thermometer to record the spatial temperature distribution and variations of volcanic lava. Silicon detectors are commonly sensitive in the near infrared wavelength range (until ca. 1100 nm), which readily allows measurements of temperatures above ca. 500 °C. The camera is modified to block the visible spectrum and the remaining colour filter (Bayer filter) characteristics are used to infer the temperature from differential intensity measurements.</p> <p class="western" lang="en-GB" align="justify">In the frame of this work, we performed a sensitivity study and calibrated the camera with a heated wire in the range of 600-1100 °C. Besides the advantages of superior mobility and simple handling, the 16 megapixel spatial resolution of the temperature measurement allows resolving detailed temperature distributions in highly dynamic volcanic emission processes.</p>

scholarly journals Numerical Simulation of a Scanning Illumination System for Deep Tissue Fluorescence Imaging

2019 ◽  
Vol 5 (11) ◽  
pp. 83
Author(s):  
Qimei Zhang ◽  
Anna M. Grabowska ◽  
Philip A. Clarke ◽  
Stephen P. Morgan
Keyword(s):  
Fluorescence Imaging ◽  
Spatial Resolution ◽  
Near Infrared ◽  
Scanning System ◽  
Deep Tissue ◽  
Full Field ◽  
Infrared Wavelength ◽  
Tissue Optical Properties ◽  
Illumination System ◽  
Tissue Fluorescence

The spatial resolution and light detected in fluorescence imaging for small animals are limited by light scattering, absorption and autofluorescence. To address this, novel near-infrared fluorescent contrast agents and imaging configurations have been investigated. In this paper, the influence of the light wavelength and imaging configurations (full-field illumination system and scanning system) on fluorescence imaging are compared quantitatively. The surface radiance for both systems is calculated by modifying the simulation tool Near-Infrared Fluorescence and Spectral Tomography. Fluorescent targets are embedded within a scattering medium at different positions. The surface radiance and spatial resolution are obtained for emission wavelengths between 620 nm and 1000 nm. It was found that the spatial resolution of the scanning system is independent of the tissue optical properties, whereas for full-field illumination, the spatial resolution degrades at longer wavelength. The full width at half maximum obtained by the scanning system is 25% lower than that obtained by the full-field illumination system when the targets are located in the middle of the phantom. The results indicate that although imaging at near-infrared wavelength can achieve a higher surface radiance, it may produce worse spatial resolution.

Near IR multichannel Raman spectroscopy with μm spatial resolution

1992 ◽  
Vol 50 (2) ◽  
pp. 1500-1501
Author(s):  
J. Barbillat ◽  
B. Roussel
Keyword(s):  
Spatial Resolution ◽  
Near Infrared ◽  
Low Frequency ◽  
Diffraction Limit ◽  
Small Samples ◽  
Optical Elements ◽  
Near Ir ◽  
Photodiode Arrays ◽  
Silicon Based ◽  
Anti Stokes

The techniques and capabilities of near infrared (NIR) multichannel microprobing are described in detail in this paper.The advantages and drawbacks of various kinds of instruments used to measure Raman spectra excited in the NIR spectral range have been extensively studied and compared. We demonstrate that a dispersive spectrometer specially designed to match the recently improved NIR multichannel detectors (silicon-based CCD,Germanium and InGaAs photodiode arrays) may provide better results than a Fourier Transform Interferometer in two fields:- spatial resolution close to the diffraction limit in a micro-Raman confocal configuration (1.5 to 2 μm) and- extension of the Raman spectrum to the low-frequency region (Stokes and Anti-Stokes).Moreover, to observe the excitation profiles of both resonance and fluorescence, a combined multichannel instrument covering the entire range from 0.4 to 1.5 μm enables the user to select the best conditions of measurement.For the study of very small samples (close to the diffraction limit),it is optically impossible to fill in the wide entrance aperture of the interferometer with the image of the sample while covering correctly the optical elements inside the interferometer.

scholarly journals A New Practical Approach for 3D Documentation in Ultraviolet Fluorescence and Infrared Reflectography of Polychromatic Sculptures as Fundamental Step in Restoration

Heritage ◽  
2019 ◽  
Vol 2 (1) ◽  
pp. 207-215 ◽  
Author(s):  
Luca Lanteri ◽  
Giorgia Agresti ◽  
Claudia Pelosi
Keyword(s):  
3D Model ◽  
Near Infrared ◽  
Organic Dyes ◽  
Low Cost ◽  
Conservation Status ◽  
Three Dimensional ◽  
Digital Camera ◽  
3D Models ◽  
Practical Approach ◽  
Digital Photogrammetry

The aim of this work is to present a new practical approach to digital photogrammetry to obtain 3D models of polychromatic sculptures under ultraviolet fluorescence and near-infrared by starting from photographic images. This digital photogrammetry was applied recently to a 17th-century reliquary bust representing St. Rodonio, a saint particularly venerated by the Orthodox Church, presently under restoration in the Laboratories of University of Tuscia and belonging to the Museum of Colle del Duomo of Viterbo (Italy). The acquisitions of ultraviolet fluorescence and infrared frames were performed using a Nikon D5300 digital SLR camera and a modified low-cost digital camera (Samsung Model NX3300), respectively. The three-dimensional UV and IR models were obtained using Agisoft PhotoScan® software. The generated ultraviolet 3D model of the bust makes visible, in a single file, the fluorescence induced by UV radiation on the entire sculpture, highlighting surface abrasions, organic dyes, and ancient protective features. The infrared 3D model allowed for better definition of the details of the drawing used for eyes, nose and mouth definition. In conclusion, the ultraviolet fluorescence and IR 3D models of Saint Rodonio were particularly useful as documentation tools for the conservation status and for the painting construction, allowing us to perfectly map the original and restoration materials and to detect the drawing in single dynamic 3D files following a totally non-invasive, cost-effective, and rapid approach.

scholarly journals Applying High-Resolution Visible-Channel Aerial Scan of Crop Canopy to Precision Irrigation Management

Proceedings ◽  
2018 ◽  
Vol 2 (7) ◽  
pp. 335 ◽  
Author(s):  
Assaf Chen ◽  
Valerie Orlov-Levin ◽  
Moshe Meron
Keyword(s):  
Vegetation Cover ◽  
Vegetation Index ◽  
Near Infrared ◽  
Normalized Difference Vegetation Index ◽  
Low Cost ◽  
Irrigation Management ◽  
Digital Camera ◽  
Canopy Cover ◽  
Crop Canopy ◽  
Irrigation Uniformity

Canopy cover (or vegetation cover) maps serve in irrigation management mainly to determine the primary evapotranspiration (ET) coefficient, as radiation interception and evaporative surface area are directly related to canopy cover. Crop size and development with time depends on water supply; therefore, crop canopy maps are tools for the detection of the spatial uniformity of irrigation systems. Several aerial scan campaigns were deployed in the Upper Galilee of Israel in the 2017 growing season to follow up and evaluate the irrigation uniformity and crop coefficients of peanuts and cotton by RGB scans of a Phantom 4 multirotor unmanned aerial vehicle (UAV). Foliage intensity and coverage were enhanced by a green-red vegetation index (GRVI), which is a normalized difference vegetation index (NDVI)-like process where the green channel replaced the near-infrared (NIR). The results demonstrated that the GRVI is suitable for the purpose of determining the vegetation cover. Furthermore, the GRVI yielded better results than the NDVI in recognizing phenological crop changes (especially senescence). Therefore, this research proves the applicability of a low-cost digital camera mounted on an easily accessible UAV for crop cover and actual, in-field, ET coefficients determination and irrigation uniformity evaluation.

scholarly journals 3D Calibration Test-Field for Digital Cameras Mounted on Unmanned Aerial Systems (UAS)

2018 ◽  
Vol 10 (12) ◽  
pp. 2017 ◽  
Author(s):  
Valeria-Ersilia Oniga ◽  
Norbert Pfeifer ◽  
Ana-Maria Loghin
Keyword(s):  
Near Infrared ◽  
Low Cost ◽  
Digital Camera ◽  
Field Measurements ◽  
Unmanned Aerial Systems ◽  
Test Field ◽  
Digital Cameras ◽  
Self Calibration ◽  
Technological Developments ◽  
Aerial Systems

Due to the large number of technological developments in recent years, UAS systems are now used for monitoring purposes and in projects with high precision demand, such as 3D model-based creation of dams, reservoirs, historical monuments etc. These unmanned systems are usually equipped with an automatic pilot device and a digital camera (photo/video, multispectral, Near Infrared etc.), of which the lens has distortions; but this can be determined in a calibration process. Currently, a method of “self-calibration” is used for the calibration of the digital cameras mounted on UASs, but, by using the method of calibration based on a 3D calibration object, the accuracy is improved in comparison with other methods. Thus, this paper has the objective of establishing a 3D calibration field for the digital cameras mounted on UASs in terms of accuracy and robustness, being the largest reported publication to date. In order to test the proposed calibration field, a digital camera mounted on a low-cost UAS was calibrated at three different heights: 23 m, 28 m, and 35 m, using two configurations for image acquisition. Then, a comparison was made between the residuals obtained for a number of 100 Check Points (CPs) using self-calibration and test-field calibration, while the number of Ground Control Points (GCPs) variedand the heights were interchanged. Additionally, the parameters where tested on an oblique flight done 2 years before calibration, in manual mode at a medium altitude of 28 m height. For all tests done in the case of the double grid nadiral flight, the parameters calculated with the proposed 3D field improved the results by more than 50% when using the optimum and a large number of GCPs, and in all analyzed cases with 75% to 95% when using a minimum of 3 GCP. In this context, it is necessary to conduct accurate calibration in order to increase the accuracy of the UAS projects, and also to reduce field measurements.

scholarly journals Epitaxial Silver Films Morphology and Optical Properties Evolution over Two Years

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 911
Author(s):  
Aleksandr S. Baburin ◽  
Anton I. Ivanov ◽  
Evgeniy S. Lotkov ◽  
Olga S. Sorokina ◽  
Irina A. Boginskaya ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Near Infrared ◽  
Low Cost ◽  
Internal Stresses ◽  
Key Factors ◽  
Silver Films ◽  
Single Crystalline ◽  
Infrared Wavelength ◽  
Bulk Structures

Silver and gold are the most commonly used materials in optics and plasmonics. Silver has the lowest optical losses in the visible and near-infrared wavelength range, but it faces a serious problem—degradation over time. It has been repeatedly reported that the optical properties of silver thin films rapidly degrade when exposed to the atmosphere. This phenomenon was described by various mechanisms: rapid silver oxidation, sorption of sulfur or oxygen, formation of silver compounds with chlorine, sulfur, and oxygen. In this work, we systematically studied single-crystalline silver films from 25 to 70 nm thicknesses for almost two years. The surface morphology, crystalline structure and optical characteristics of the silver films were measured using spectroscopic ellipsometry, ultra-high-resolution scanning electron microscopy, and stylus profilometry under standard laboratory conditions. After 19 months, bulk structures appeared on the surface of thin films. These structures are associated with relaxation of internal stresses combined with dewetting. Single-crystalline silver films deposited using the single-crystalline continuous ultra-smooth, low-loss, low-cost (SCULL) technology with a thickness of 35–50 nm demonstrated the best stability in terms of degradation. We have shown that the number of defects (grain boundaries and joints of terraces) is one of the key factors that influence the degradation intensity of silver films.

scholarly journals In Vivo Recognition of Vascular Structures by Near-Infrared Transillumination

Proceedings ◽  
2019 ◽  
Vol 42 (1) ◽  
pp. 24
Author(s):  
Valentina Bello ◽  
Elisabetta Bodo ◽  
Sara Pizzurro ◽  
Sabina Merlo
Keyword(s):  
Semiconductor Lasers ◽  
Near Infrared ◽  
Low Cost ◽  
Full Range ◽  
Digital Camera ◽  
Biological Tissues ◽  
Dorsal Vein ◽  
Spatially Distributed ◽  
Vascular Structures

Transillumination is a very well-known non-invasive optical technique that relies on the use of non-ionizing radiation to obtain information about the internal morphology of biological tissues. In a previous work, we implemented a laser-based illuminator operating at a wavelength of 850 nm, combined with a CMOS digital camera and narrow-band optical detection that showed great potential for in vivo imaging. A great advantage is the use of low-cost semiconductor lasers, driven by a very low current (about 11 mA, spatially distributed as a 6-by-6 matrix covering a 25 cm2 area). Thanks to the strong absorption of hemoglobin at this wavelength, we have collected raw data of vascular structures that have been further processed to achieve images with much better quality. In particular, here we show that a higher contrast can be attained by the expansion of gray level histograms to exploit the full range, 0–255. This elaboration can be, for instance, exploited for the recognition of vascular structures with better resolution. Examples are reported relative to hand dorsal vein patterns and live chick embryos’ blood vessels. Analyses can be successfully performed without applying any thermal or mechanical stress to the human tissue under test and without damaging or puncturing any parts of the eggshell.

scholarly journals ACCURACY ASSESSMENT OF COASTAL TOPOGRAPHY DERIVED FROM UAV IMAGES

2016 ◽  
Vol XLI-B1 ◽  
pp. 1127-1134 ◽  
Author(s):  
N. Long ◽  
B. Millescamps ◽  
F. Pouget ◽  
A. Dumon ◽  
N. Lachaussée ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Laser Scanning ◽  
Accuracy Assessment ◽  
Low Cost ◽  
Temporal Frequency ◽  
Digital Camera ◽  
Image Resolution ◽  
Homogeneous Distribution ◽  
Surface Model ◽  
Small Water

To monitor coastal environments, Unmanned Aerial Vehicle (UAV) is a low-cost and easy to use solution to enable data acquisition with high temporal frequency and spatial resolution. Compared to Light Detection And Ranging (LiDAR) or Terrestrial Laser Scanning (TLS), this solution produces Digital Surface Model (DSM) with a similar accuracy. To evaluate the DSM accuracy on a coastal environment, a campaign was carried out with a flying wing (eBee) combined with a digital camera. Using the Photoscan software and the photogrammetry process (Structure From Motion algorithm), a DSM and an orthomosaic were produced. Compared to GNSS surveys, the DSM accuracy is estimated. Two parameters are tested: the influence of the methodology (number and distribution of Ground Control Points, GCPs) and the influence of spatial image resolution (4.6 cm vs 2 cm). The results show that this solution is able to reproduce the topography of a coastal area with a high vertical accuracy (< 10 cm). The georeferencing of the DSM require a homogeneous distribution and a large number of GCPs. The accuracy is correlated with the number of GCPs (use 19 GCPs instead of 10 allows to reduce the difference of 4 cm); the required accuracy should be dependant of the research problematic. Last, in this particular environment, the presence of very small water surfaces on the sand bank does not allow to improve the accuracy when the spatial resolution of images is decreased.

scholarly journals ACCURACY ASSESSMENT OF COASTAL TOPOGRAPHY DERIVED FROM UAV IMAGES

2016 ◽  
Vol XLI-B1 ◽  
pp. 1127-1134 ◽  
Author(s):  
N. Long ◽  
B. Millescamps ◽  
F. Pouget ◽  
A. Dumon ◽  
N. Lachaussée ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Laser Scanning ◽  
Accuracy Assessment ◽  
Low Cost ◽  
Temporal Frequency ◽  
Digital Camera ◽  
Image Resolution ◽  
Homogeneous Distribution ◽  
Surface Model ◽  
Small Water

To monitor coastal environments, Unmanned Aerial Vehicle (UAV) is a low-cost and easy to use solution to enable data acquisition with high temporal frequency and spatial resolution. Compared to Light Detection And Ranging (LiDAR) or Terrestrial Laser Scanning (TLS), this solution produces Digital Surface Model (DSM) with a similar accuracy. To evaluate the DSM accuracy on a coastal environment, a campaign was carried out with a flying wing (eBee) combined with a digital camera. Using the Photoscan software and the photogrammetry process (Structure From Motion algorithm), a DSM and an orthomosaic were produced. Compared to GNSS surveys, the DSM accuracy is estimated. Two parameters are tested: the influence of the methodology (number and distribution of Ground Control Points, GCPs) and the influence of spatial image resolution (4.6 cm vs 2 cm). The results show that this solution is able to reproduce the topography of a coastal area with a high vertical accuracy (< 10 cm). The georeferencing of the DSM require a homogeneous distribution and a large number of GCPs. The accuracy is correlated with the number of GCPs (use 19 GCPs instead of 10 allows to reduce the difference of 4 cm); the required accuracy should be dependant of the research problematic. Last, in this particular environment, the presence of very small water surfaces on the sand bank does not allow to improve the accuracy when the spatial resolution of images is decreased.

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