Search results for "Visibility"
showing 10 items of 149 documents
Optimal design of incoherent tunable-frequency structured illumination microscope scheme
2018
Structured illumination microscopy (SIM) improves resolution and optical sectioning capability compared to conventional widefield techniques. The main idea of this method is the illumination of the sample with a structured pattern of fixed spatial modulation frequency. Previously, a Fresnel biprism has been implemented in a structured illumination (SI) device providing tunable-frequency sinusoidal patterns. However, the use of this SI system introduces a tradeoff between the visibility and field of view of the illumination fringes. In this contribution, we analyze theoretically this tradeoff and propose the optimal design for the Fresnel biprism-based SIM system.
Roving Robots Gain from an Orientation Algorithm of Fruit Flies and Predict a Fly Decision-Making Algorithm
2014
Simple organisms like bacteria are directly influenced by momentary changes in concentration or strength of sensory signals. In noisy sensory gradients frequent zigzagging reduces the performance of the cell or organism. Drosophila melanogaster flies significantly deviate from a direct response to sensory input when orienting in gradients. A dynamical model has been derived which reproduces fly behaviour. Here we report on an emergent property of the model. Implemented in a robot, the algorithm is sustaining decisions between visual targets. The behaviour was consequently found in wild-type flies, which stay with a once-chosen visual target for considerable longer times than mutant flies wi…
Asynchronous Occlusion Culling on Heterogeneous PC Clusters for Distributed 3D Scenes
2012
We present a parallel rendering system for heterogeneous PC clusters to visualize massive models. One single, powerful visualization node is supported by a group of backend nodes with weak graphics performance. While the visualization node renders the visible objects, the backend nodes asynchronously perform visibility tests and supply the front end with visible scene objects. The visualization node stores only currently visible objects in its memory, while the scene is distributed among the backend nodes’ memory without redundancy. To efficiently compute the occlusion tests in spite of that each backend node stores only a fraction of the original geometry, we complete the scene by adding h…
Can the Excluded Criticize? On the (Im)possibilities of Formulating and Understanding Critique
2021
If critique does not want to be more than just a ‘passion of the head’ it has to engage in dialogue with the worst-off in society. However, there are several mechanisms that hinder the excluded fro...
Holographic photoelasticity: Influences of inaccuracies of optical retarders on isochromatics and isopachics
1974
In this paper the influence of inaccuracies of the optical retarders on the isochromatic and isopachic fringes obtained by holographic photoelasticity is studied. For the single-exposure hologram it is shown that the isochromatic visibility decreases as for light- and dark-field configurations, whereas the isochromatic fringes are distorted only for the dark-field configuration. For the double-exposure hologram it is shown that the isopachic fringes are generally distorted; with the isochromatics there is a decrease of fringe visibility. Experimental results confirming the theory are reported.
Visibility forecast in the phase of pre-condensation
1969
The effect on visibility of the swelling of aerosol particles due to increasing humidity is studied. The swelling can be described by r(f)/r (0) = (1 - f ) ?1/? where r ( f ) = particle radius at relative humidity f and ? = const ? 4 on the average. The visibility variation is expressed as V(f)/V(f 0 ) = [(1 - f )/(1 - f 0 )] V * ? 1)/? where V * = exponent of the aerosol size distribution ? 3 on the average. The last formula allows to compute the standard visual range V(f) at relative humidity f from the present standard visual range V(f 0 ) at present relative humidity f 0 . DOI: 10.1111/j.2153-3490.1969.tb00469.x
Measurement of the Sensitivity Function in a Time-Domain Atomic Interferometer
2008
We present here an analysis of the sensitivity of a time-domain atomic interferometer to the phase noise of the lasers used to manipulate the atomic wave packets. The sensitivity function is calculated in the case of a three-pulse Mach-Zehnder interferometer, which is the configuration of the two inertial sensors we are building at the Laboratoire National de Metrologie et d'Essais-Systeme de References Temps-Espace. We successfully compare this calculation to experimental measurements. The sensitivity of the interferometer is limited by the phase noise of the lasers as well as by residual vibrations. We evaluate the performance that could be obtained with state-of-the-art quartz oscillator…
Structural Variability of 3C 111 on Parsec Scales
2012
We discuss the parsec-scale structural variability of the extragalactic jet 3C111 related to a major radio flux density outburst in 2007. The data analyzed were taken within the scope of the MOJAVE, UMRAO, and F-GAMMA programs, which monitor a large sample of the radio brightest compact extragalactic jets with the VLBA, the University of Michigan 26 m, the Effelsberg 100 m, and the IRAM 30m radio telescopes. The analysis of the VLBA data is performed by fitting Gaussian model components in the visibility domain. We associate the ejection of bright features in the radio jet with a major flux-density outburst in 2007. The evolution of these features suggests the formation of a leading compone…
Three-Dimensional Mapping and Ranging of Objects Using Speckle Pattern Analysis
2010
In this chapter, we present two novel approaches for 3-D object shape measurement and range estimation based on digital image processing of speckle patterns. In the first one, 3-D mapping and range measurement are retrieved by projecting, through a ground glass diffuser, random speckle patterns on the object or on the camera for a transmissive and reflective configuration, respectively. Thus, the camera sensor records in time sequence different speckle patterns at different distances, and by using correlation operation between them, it is possible to achieve 3-D mapping and range finding. In the second one, the 3-D mapping and ranging are performed by sensing the visibility associated with …
Talbot array illuminators with binary phase gratings
2009
We establish that, in six different cases, binary phase gratings can be applied to implement Talbot array illuminators. Three of the six cases are reported for what is to our knowledge the first time.