Dynamic properties of biological samples are studied by means of the speckle phenomenon. A non–invasive optical technique for measuring the dynamic response of a tomato leaflet to its detachment from ...the plant is developed and tested. The technique uses the subtraction of consecutive images of speckle patterns. To quantify changes in the dynamic response of the tested sample, two statistical indicators based on standard deviation are introduced. They allow to analyse the temporal progress of dynamic response in both the whole selected region of the leaflet and different points of this region. Dynamic processes reflecting stress responses passing over the vascular bundle and mesophyll cells of the leaflet are investigated. Although the processes in the vascular bundle gradually cease, the ones in the mesophyll cells exhibit the opposite response to stress. Significant dynamic response heterogeneity is detected within a single leaflet designating this optical technique for opening up a new avenue for non-invasive monitoring of biological samples.
•The optical technique based on speckle for monitoring leaflet structural changes.•Introduced indicators quantify the extent and trend of leaflet dynamic processes.•Dynamic response to desiccation stress in mesophyll cells is opposite to main vein.•The mesophyll desiccates and the veins keep water longer with minimum dynamics.•The optical technique complements the terahertz measuring methods.
The origin and nature of ultrahigh-energy cosmic rays (UHECRs) are of uppermost importance in astroparticle physics. Motivated by the need for an unprecedented aperture for further advancements, the ...Fluorescence detector Array of Single-pixel Telescopes (FAST) is a prospective next-generation, ground-based UHECR observatory that aims to cover an enormous area by deploying a large array of low-cost fluorescence telescopes. The full-scale FAST prototype consists of four 20 cm photomultiplier tubes at the focus of a segmented mirror 1.6 m in diameter. Three FAST prototypes have been installed at the Telescope Array Experiment in Utah, USA, and two prototypes at the Pierre Auger Observatory in Mendoza, Argentina, commencing remote observation of UHECRs in both hemispheres. We report on recent results of the full-scale FAST prototypes operated in both hemispheres, including telescope calibrations, atmospheric monitoring, ongoing electronics upgrades, development of sophisticated reconstruction methods and UHECR detections.
Nowadays, the need for extended uniform light sources increases in many different areas of optics. Integrating spheres show one of the best properties among them. The paper is focused on verification ...of the practical use of so-called general purpose integrating spheres for the purpose of the calibration of highly sensitive detectors in the near-UV spectrum. To achieve this, the summarization of the theory of the integrating spheres is given, the methodology of the measurement is described and a universal experimental setup is designed. The setup is able to measure the real spatial and angular radiance uniformity of the exit port of selected representative of integrating spheres. The results of radiance uniformity measurements are graphically presented and discussed.
•1D correlation method of a long vector for speckle size determination is presented.•The new method and known average 1D correlation method are compared.•No requirement to enlarge the area of speckle ...pattern detection.•The new method brings more accurate results than the average 1D correlation method.
In this paper one-dimensional correlation method for determination of a mean speckle size is used, while two various approaches are presented. It is shown, that accuracy of the measurement by the method depends on a number of speckles in an evaluated one-dimensional intensity profile of detected speckle pattern. It is also shown, that a significant optimization of the method by reduction of a number of intensity values representing detected speckle patterns can be performed. This study is carried out for several speckle patterns generated through a numerical simulation of the speckle fields after reflection of a Gaussian beam off a rough object’s surface. Results of the determination of the mean speckle size are compared with theoretical predictions.
The presented paper deals with the data processing of correlograms acquired by an electronic speckle pattern interferometry (ESPI). Correlograms are highly noised by the speckle pattern and special ...care should be taken to denoise these correlograms before calculating the demanded phase map or phase profile. This paper presents a process that utilizes two stage use of wavelet transform (WT) for both denoising and a phase profile retrieval. In the first stage the correlogram is denoised by thresholding of wavelet transform coefficients. Unlike the common use, WT phase retrieval process is not directly applied to the denoised correlogram, but rather to its intensity thresholded image, which is done in the second stage. Proposed algorithm is verified by its application to the artificially generated correlograms and in the final step also to the experimentally acquired correlograms.
The origin and nature of ultrahigh-energy cosmic rays (UHECRs) is one of the most intriguing and important mysteries in astroparticle physics. The two largest observatories currently in operation, ...the Telescope Array Experiment in central Utah, USA, and the Pierre Auger Observatory in western Argentina, have been steadily observing UHECRs in both hemispheres for over a decade. We highlight the latest results from both of these experiments, and address the requirements for a next-generation UHECR observatory. The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a design concept for a next-generation UHECR observa-tory, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the highest energy cosmic rays with an unprecedented aperture. We have developed a full-scale prototype consisting of four 200 mm photomultiplier-tubes at the focus of a segmented mirror of 1.6 m in diameter. Over the last three years, we installed three such prototypes at the Black Rock Mesa site of the Telescope Array Experiment. These telescopes have been steadily taking data since installation. We report on preliminary results of the full-scale FAST prototypes, including measurements of distant ultraviolet lasers and UHECRs. Futhermore, we discuss our plan to install an additional identical FAST prototype at the Pierre Auger Observatory. Possible benefits to the Telescope Array and the Pierre Auger Observatory include a comparison of the transparency of the atmosphere above both experiments, a study of the systematic uncertainty associated with their existing fluorescence detectors, and a cross-calibration of their energy and
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The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a proposed low-cost, largearea, next-generation experiment for the detection of ultrahigh-energy cosmic rays (UHECRs) via the ...atmospheric fluorescence technique. Two FAST telescopes are currently installed and operating at the Black Rock Mesa site of the Telescope Array Experiment in Utah, USA. Knowledge of the properties of the atmosphere above the detector is of utmost importance for the analysis and reconstruction of the energy and trajectory of UHECRs measured with an atmospheric fluorescence telescope. The FAST experiment uses all sky camera (FASCam) and sky quality monitor (SQM) for the detection of clouds and quantification of the night-sky background light in the field-of-view of the telescopes. Measurements of a vertically-fired ultra-violet laser at a distance of 21 km from the FAST telescopes are used to infer the transparency of the atmosphere above the detector through comparison with simulations.
The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a proposed large-area, next-generation experiment for the detection of ultra-high energy cosmic rays via the atmospheric ...fluorescence technique. The telescope’s large field-of-view (30 ×30) is imaged by four 200 mm photomultiplier-tubes at the focal plane of a segmented spherical mirror of 1.6 m diameter. Two prototypes are installed and taking data at the Black Rock Mesa site of the Telescope Array experiment in central Utah, USA. We present the process used for optimization of the optical performance of this compact and low-cost telescope, which is based on a simulation of the telescope’s optical point spread function.
We present a concept for large-area, low-cost detection of ultrahigh-energy cosmic rays (UHECRs) with a Fluorescence detector Array of Single-pixel Telescopes (FAST)b, addressing the requirements for ...the next generation of UHECR experiments. In the FAST design, a large field of view is covered by a few pixels at the focal plane of a mirror or Fresnel lens. We report on the first results of a FAST prototype installed at the Telescope Array (TA) site, consisting of a single 200 mm photomultiplier tube (PMT) at the focal plane of a 1 m2 Fresnel lens system taken from the prototype of the JEM-EUSO experiment. We also report on the status of the full-scale FAST prototype soon to be installed at the TA site, comprising a segmented spherical mirror of 1.6 m diameter and a 2 × 2 PMT camera.
We present a measurement of an object's in-plane velocity in one direction by the use of the speckle correlation method. Numerical correlations of speckle patterns recorded periodically during motion ...of the object under investigation give information used to evaluate the object's in-plane velocity. The proposed optical setup uses a detection plane in the image field and enables one to detect the object's velocity within the interval (10-150) microm x s(-1). Simulation analysis shows a way of controlling the measuring range. The presented theory, simulation analysis, and setup are verified through an experiment of measurement of the velocity profile of an object.
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