Real-time liquid-crystal atmosphere turbulence simulator with graphic processing unit

Multiphoton microscopy (MPM) is a remarkably versatile technique in biologicalimaging. MPM provides increased depth over confocal imaging and can be combined with other imaging techniques such as fluorescence lifetime imaging microscopy (FLIM), adding functional information. FLIM read--out is relatively straightforward using time--correlated single photon counting (TCSPC). Fluorescence lifetime detection enhances the power of multiphoton imaging to allow three dimensional, concentration independent, measurements of environmental parameters such as pH, Oxygen tension and Ca 2+ in addtion to the interaction or conformational modification of proteins by Förster resonant energy transfer (FRET); the latter is a particular focus of the Dimbleby research groups at King's CollegeLondon. However, there are significant limitations in both FLIM and MM.Limitations of TCSPC--FLIM include prolonged acquisition times along with signal and resolution degradation as a function of depth. This thesis demonstrates advancements multiphoton fluorescence lifetime imaging through improvements in two principal areas: speed and resolution at depth.In order to improve acquistion rates a multifocal multiphoton microscope (MMM) capable of rapid, parallelized TCSPC--FLIM was developed --MegaFLI. Acquisitions demonstrate rapid 3--dimensional, high temporal resolution FLIM in vivo Zebrafish.Performed by massively parallel excitation/detection the speed is signficantly improved by a factor of 64.In parallel to the MegaFLI project, a second microscope employing adaptive optical correction has been developed. The introduction of Adaptive Optics (AO) serves to improve imaging quality by counteracting the refractive index heterogeneities introduced by the sample, limiting the imaging depth. Incorporated with a single beam scanning FLIM system, a pupil--segmentation AO--TCSPC--FLIM demonstrates improved signal--to--noise ratio (SNR) and resolution, permiting a more accurate determination of fluorescent lifetime in turbid media. 3 DECLARATION OF AUTHORSHIPThe work present is my own work with the exception of TRI2, which was developed The introduction (Chapter 1) concentrates on optical methods developed in the context of multiphoton microscopy (MPM) or more specifically two--photon microscopy (TPM) (Denk et al., 1990). TPM enables long--term imaging of in vivo biological specimens, image generation at increased tissue depth, and higher signal--to--noise images compared to wide--field and confocal approaches (Helmchen and In comparison to confocal microscopy, two--photon microscopy (TPM) offers considerable benefits since excitation is confined to a femtolitre volume in the vicinity of the focal plane, reducing overall photobleaching and phototoxicity of thick samples (Centonze and White, 1998;Denk et al., 1990;Helmchen and Denk, 2005;Williams et al., 2001). Out--of--focus excitation is avoided due to the localization of the excitation making the confocal pinhole obsolete (Amos and Where is the numerical aperture of the obj...

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“…and ! and using a binomial expansion while retaining the first three terms (Hu et al, 2009 (Wang et al, 2005).…”

Section: Huygens--fresnel Diffractive Lens Arraymentioning

confidence: 99%

Multifocal multiphoton microscopy with adaptive optical correction

et al. 2013

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“…For this particular application, each thread in the thread block executes identical instructions (called the kernel) for each pixel. Optics-related applications of GPU technology include holography, 10, 11 real-time shape measurements, 12 atmospheric turbulence, 13 and Monte Carlo modeling of light transport. 14,15 An excellent description of GPUs is provided in Ref.…”

Section: Lsi Algorithm Implementation In Cudamentioning

confidence: 99%

Real-time blood flow visualization using the graphics processing unit

2011

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Abstract. Laser speckle imaging (LSI) is a technique in which coherent light incident on a surface produces a reflected speckle pattern that is related to the underlying movement of optical scatterers, such as red blood cells, indicating blood flow. Image-processing algorithms can be applied to produce speckle flow index (SFI) maps of relative blood flow. We present a novel algorithm that employs the NVIDIA Compute Unified Device Architecture (CUDA) platform to perform laser speckle image processing on the graphics processing unit. Software written in C was integrated with CUDA and integrated into a LabVIEW Virtual Instrument (VI) that is interfaced with a monochrome CCD camera able to acquire high-resolution raw speckle images at nearly 10 fps. With the CUDA code integrated into the LabVIEW VI, the processing and display of SFI images were performed also at ∼10 fps. We present three video examples depicting real-time flow imaging during a reactive hyperemia maneuver, with fluid flow through an in vitro phantom, and a demonstration of real-time LSI during laser surgery of a port wine stain birthmark. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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“…Atmospheric emulators made with spatial light modulators (SLMs) offer the ability to test a laser communication component's performance while in the laboratory with a broad range of turbulence levels [1][2][3][4][5][6][7][8][9][10][11][12][13] . When compared to rotating phase plates [14][15][16][17][18] (another common option for emulating atmosphere in the laboratory), SLM based systems have a speed limitation, restricting real time recreation of atmospheric optical turbulence evolving at typical Greenwood frequencies.…”

Section: Introductionmentioning

confidence: 99%

“…Commonly, SLM-based emulators are designed using a phase screen approach 1,4,6,9,10 . The phase screen approach loses fidelity for lower elevation propagation paths due to the intensity nulls which form in conjunction with branch points in deep turbulence.…”

Section: Introductionmentioning

confidence: 99%

Folded optical design for high fidelity atmospheric emulation with a spatial light modulator

Tedder

Chahine

2023

Free-Space Laser Communications XXXV

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Atmospheric emulators based on spatial light modulators offer the ability to test atmospheric propagation effects on a laser communication component's performance in the laboratory setting. To create a high-fidelity atmospheric emulator, details of the optical design are key. This paper discusses the optical design choices and refinements that enabled the creation of a system that was verified to recreate multi-layer turbulence with high fidelity up to D/r0 =50. Optical design choices that affect the fidelity discussed in this paper include the characteristics of the input laser, the spatial light modulator, the holograms, the image relay optical components, and the spatial filter. Also included in this paper is a comparison of the chosen folded optical layout to an alternative angled layout.

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Real-time liquid-crystal atmosphere turbulence simulator with graphic processing unit

Cited by 8 publications

References 25 publications

Multifocal multiphoton microscopy with adaptive optical correction

Multifocal multiphoton microscopy with adaptive optical correction

Real-time blood flow visualization using the graphics processing unit

Folded optical design for high fidelity atmospheric emulation with a spatial light modulator

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