Search results for " illumination"
showing 10 items of 38 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.
Structured-light imaging through scattering
2016
We present a structured illumination technique to image objects hidden beneath scattering. The sample is computationally retrieved from a known ensemble of light patterns codified onto a digital micromirror device and photocurrent fluctuations provided by a detector with no spatial resolution. Results of laboratory experiments will be shown. Article not available.
Tunable structured illumination system based on a Wollaston prism
2018
Experimental verification of a simple illumination system to generate a 1D structured pattern with tunable modulation frequency is shown based on a Wollaston prism illuminated by the diffracted field of an incoherent linear source.
A novel 3D recovery method by dynamic (de)focused projection
2011
This paper presents a novel 3D recovery method based on structured light. This method unifies depth from focus (DFF) and depth from defocus (DFD) techniques with the use of a dynamic (de)focused projection. With this approach, the image acquisition system is specifically constructed to keep a whole object sharp in all of the captured images. Therefore, only the projected patterns experience different defocused deformations according to the object’s depths. When the projected patterns are out of focus, their Point Spread Function (PSF) is assumed to follow a Gaussian distribution. The final depth is computed by the analysis of the relationship between the sets of PSFs obtained from different…
Quantitative Multispectral Imaging Differentiates Melanoma from Seborrheic Keratosis.
2021
Melanoma is a melanocytic tumor that is responsible for the most skin cancer-related deaths. By contrast, seborrheic keratosis (SK) is a very common benign lesion with a clinical picture that may resemble melanoma. We used a multispectral imaging device to distinguish these two entities, with the use of autofluorescence imaging with 405 nm and diffuse reflectance imaging with 525 and 660 narrow-band LED illumination. We analyzed intensity descriptors of the acquired images. These included ratios of intensity values of different channels, standard deviation and minimum/maximum values of intensity of the lesions. The pattern of the lesions was also assessed with the use of particle analysis. …
Knowledge engineering and semantic formalism of symbolic relations. From medieval network to web 3.0
2020
A search has always been at the center of human concerns, the one of conditions and means to represent, to control well, and to communicate effectively with his environment. While technological advances and electronic gadgets such as smartphones, the Web, and online social networks currently allow addressing this concern, it has not always been the case. Our works in this thesis treat medieval documents considered as a medium of communication and as a model of the social network in the Middle Ages. These documents are called medieval illuminations. They were luxurious paintings used in that time to represent the environment and ideal world for elites such as prince, duke, etc. Those paintin…
A Simulation of daylight levels for the determination of visual comfort in large spaces
2007
In sizable environments, such as the collective areas of a big university building, characterised by very long corridors, large hallways and broad glazed surfaces, the daytime illumination factor is often only excellent near to the latter, due to their predominantly horizontal, rather than vertical, nature. His study, which has been carried out thanks to a simulation software, shows the results of a correlation between light contributions, come out from the wide glass surface and those of a big skylight which cross lenghtways the main part of the building. Such results have been compared with some instrumental measurements considering the shifting and getting from them important information…
«Il sunt si biaus que c'en est une mervoie a voir». Zoologie e teratologie nel Devisement dou monde
2016
L’articolo ha come oggetto le descrizioni animali e teratologiche del Devisement dou monde. In particolare, la fauna poliana con le sue estremizzazioni mostruose e meravigliose viene indagata sul doppio filo del testo franco-italiano del Devisement (accompagnato, laddove necessario, dall’ausilio delle redazioni toscana e latina) e dell’iconografia rappresentata dalle miniature contenute in quattro codici del Devisement/Milione (mss. Royal 19 D I, Bodley 264, BNF fr. 2810, Arsenal 5219). The present article investigates animal and teratological descriptions of theDevisement dou monde. Particularly, Marco Polo’s fauna and its monstrous and marvelous extremes are explored both in the Franco-It…
Synthetic aperture microscopy using off-axis illumination and polarization coding
2007
A new method to improve the resolution of optical imaging systems beyond the classical Rayleigh resolution limit is presented. The technique relies on synthetic aperture generation in three stages. The first one (encoding stage) uses an illumination procedure that combines both on-axis and off-axis illumination beams with different polarization states onto the object. After the imaging system, a second stage (decoding stage) allows the recovering of the encoded spatial-frequency object information by means of an interferometric configuration based on the polarization coding carried out in the previous stage. Finally, a third stage (digital post-processing stage) is used to generate a synthe…
Development of a High Irradiance LED Configuration for Small Field of View Motion Estimation of Fertilizer Particles
2015
International audience; Better characterization of the fertilizer spreading process, especially the fertilizer pattern distribution on the ground, requires an accurate measurement of individual particle properties and dynamics. Both 2D and 3D high speed imaging techniques have been developed for this purpose. To maximize the accuracy of the predictions, a specific illumination level is required. This paper describes the development of a high irradiance LED system for high speed motion estimation of fertilizer particles. A spectral sensitivity factor was used to select the optimal LED in relation to the used camera from a range of commercially available high power LEDs. A multiple objective …