FLIM and FCS detection in laser‐scanning microscopes: Increased efficiency by GaAsP hybrid detectors

Becker, Wolfgang; Su, Bertram; Holub, Oliver; Weißhart, Klaus

doi:10.1002/jemt.20959

Cited by 74 publications

(53 citation statements)

References 25 publications

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“…All PMTs were manufactured by Hamamatsu Photonics, Hamamatsu, Japan; HPM-100-50 is a hybrid detector module (Becker & Hickl GmbH) based on a Hamamatsu R10467 tube. 33 …”

Section: Instrumentsmentioning

confidence: 99%

Performance assessment of time-domain optical brain imagers, part 1: basic instrumental performance protocol

et al. 2014

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Abstract. Performance assessment of instruments devised for clinical applications is of key importance for validation and quality assurance. Two new protocols were developed and applied to facilitate the design and optimization of instruments for time-domain optical brain imaging within the European project nEUROPt. Here, we present the "Basic Instrumental Performance" protocol for direct measurement of relevant characteristics. Two tests are discussed in detail. First, the responsivity of the detection system is a measure of the overall efficiency to detect light emerging from tissue. For the related test, dedicated solid slab phantoms were developed and quantitatively spectrally characterized to provide sources of known radiance with nearly Lambertian angular characteristics. The responsivity of four time-domain optical brain imagers was found to be of the order of 0.1 m 2 sr. The relevance of the responsivity measure is demonstrated by simulations of diffuse reflectance as a function of source-detector separation and optical properties. Second, the temporal instrument response function (IRF) is a critically important factor in determining the performance of time-domain systems. Measurements of the IRF for various instruments were combined with simulations to illustrate the impact of the width and shape of the IRF on contrast for a deep absorption change mimicking brain activation. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…All PMTs were manufactured by Hamamatsu Photonics, Hamamatsu, Japan; HPM-100-50 is a hybrid detector module (Becker & Hickl GmbH) based on a Hamamatsu R10467 tube. 33 …”

Section: Instrumentsmentioning

confidence: 99%

Performance assessment of time-domain optical brain imagers, part 1: basic instrumental performance protocol

et al. 2014

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“…The signals in the two spectral intervals are detected by fast TCSPC detectors, D1 and D2. Early systems used MCP PMTs, recent systems use hybrid detectors [5].…”

Section: Technical Implementationmentioning

confidence: 99%

Fluorescence Lifetime Imaging in Ophthalmology

Schweitzer

Hammer

2015

Springer Series in Chemical Physics

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Beginning disease in biological systems is often accompanied or preceded by changes in the metabolism of the tissue. Changes in the metabolism induce changes in the fluorescence decay functions of endogenous fluorophores. FLIM of the fundus of the eye is therefore a promising technique of detection early stages of eye diseases. Ophthalmic FLIM faces the problem that the excitation power is limited to very low levels, the transmission wavelength range of the ocular media is limited, the fluorescence intensities are low, and the decay functions of the fluorophores in the fundus are multi-exponential with extremely fast decay components. The task is further complicated by strong fluorescence of the lens of the eye and by the fact that the eye is constantly moving. We will show that these problems can be solved by a combination of multi-dimensional TCSPC with confocal scanning. This chapter gives a survey of the fluorophores found in the fundus, their fluorescence-decay properties, and the options to excite them at wavelengths that pass the ocular medium. It discusses the technical requirements to an ophthalmic FLIM system and describes the implementation of TCSPC FLIM in an ophthalmic scanning system for clinical use. The results obtained with the system allow fluorescence decay components to be associated to lateral and longitudinal anatomical structures of the eye, and to pathological alterations in the fundus. Statistical evaluation of the fluorescence decay parameters improves the identification of eye diseases and even detects phospho τ 181 protein in the eyes of Alzheimer patients.

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“…Moreover, due to its intensity dependent time-response it is not ideal for FLIM with large intensity differences. The best detectors currently available are hybrid detectors which consist of a photocathode in front of an avalanche photodiode (APD, biased below the diode breakdown voltage) (Becker et al, 2011b). The single photoelectrons liberated by photons at the photocathode are accelerated across a high voltage (8 kV) into the APD.…”

Section: Flim Implementationsmentioning

confidence: 99%

Fluorescence lifetime imaging (FLIM): Basic concepts and some recent developments

et al. 2015

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FLIM and FCS detection in laser‐scanning microscopes: Increased efficiency by GaAsP hybrid detectors

Cited by 74 publications

References 25 publications

Performance assessment of time-domain optical brain imagers, part 1: basic instrumental performance protocol

Performance assessment of time-domain optical brain imagers, part 1: basic instrumental performance protocol

Fluorescence Lifetime Imaging in Ophthalmology

Fluorescence lifetime imaging (FLIM): Basic concepts and some recent developments

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