Gerhard Alfred Holst

Excelitas PCO GmbH · Product Management

High-resolution optical fluorescence microscopies and, in particular, super-resolution fluorescence microscopy, are rapidly adopting highly sensitive cameras as their preferred photodetectors. Camera-based parallel detection facilitates high-speed live cell imaging with the highest spatial resolution. Here, we show that the drive to use ever more s...

High-resolution optical fluorescence microscopies and, in particular, super-resolution fluorescence microscopy, are rapidly adopting highly sensitive cameras as their referred photodetectors. Camera-based parallel detection facilitates high-speed live cell imaging with the highest spatial resolution. Here, we show that the drive to use ever more se...

In April 2020, the QUality Assessment and REProducibility for Instruments and Images in Light Microscopy (QUAREP-LiMi) initiative was formed. This initiative comprises imaging scientists from academia and industry who share a common interest in achieving a better understanding of the performance and limitations of microscopes and improved quality c...

A modern day light microscope has evolved from a tool devoted to making primarily empirical observations to what is now a sophisticated, quantitative device that is an integral part of both physical and life science research. Nowadays, microscopes are found in nearly every experimental laboratory. However, despite their prevalent use in capturing a...

A modern day light microscope has evolved from a tool devoted to making primarily empirical observations to what is now a sophisticated, quantitative device that is an integral part of both physical and life science research. Nowadays, microscopes are found in nearly every experimental laboratory. However, despite their prevalent use in capturing a...

In this contribution investigations with fluorescence lifetime imaging microscopy (FLIM) are made to optically distinguish polymers and wood. The results show that the distinction and identification is possible in a graphical and calculative way.

Fluorescence guided neurosurgery based on 5-aminolevulinic acid (5-ALA) has significantly increased maximal safe resections. Fluorescence lifetime imaging (FLIM) of 5-ALA could further boost this development by its increased sensitivity. However, neurosurgeons require real-time visual feedback which was so far limited in dual-tap CMOS camera based...

Today's camera systems used for machine vision and scientific applications have intra-scene dynamic ranges up to 16 bit and therefore A/D converters with up to 16 bit resolution per pixel. Unfortunately, the linear amplification of electrons also forces a linear or even quadratic increase of the image noise variance with the signal. Based on a meth...

Luminescence lifetime based imaging is still the most reliable method for generating chemical images using chemical sensor technology. However, only few commercial systems are available that enable imaging lifetimes within the relevant ns to µs range. In this technical note we compare the performance of an older time-domain (TD) based camera system...

The applicability of frequency-domain fluorescence lifetime imaging (FLIM) with a newly developed CMOS camera sensor (pco.flim) to Pressure-Sensitive Paint (PSP) measurements in wind tunnel tests was investigated. Two lifetime parameters, the phase angle and demodulation index, can be used as a function of pressure in FLIM technique. First, the cha...

Novel fluorescent diazaoxatriangulenium (DAOTA) pH indicators for lifetime-based self-referenced pH sensing are reported. The DAOTA dyes were decorated with phenolic receptor groups inducing fluorescence quenching via photoinduced electron transfer mechanism. Electron-withdrawing chlorine substituents ensure response in the most relevant pH range (...

Frequency-domain fluorescence lifetime imaging (FLIM) is applied for acquiring pressure sensitive paint (PSP) images by using a pco.flim camera, which has an in-pixel dual tap control CMOS image sensor. In this FLIM technique, an excitation light is modulated sinusoidally, and modulation depth and phase angle, which depend on lifetime or pressure,...

Pressure-Sensitive Paint (PSP) measurement technique is based on the change of the intensity or decay time of its luminescence with pressure, brought about by oxygen quenching. For the so called “lifetime method” the pressure dependent luminescence decay time must be detected. Two approaches exist for this type of measurement: The time-domain lifet...

Light-sheet microscopy has become an indispensable tool for fast, low phototoxicity volumetric imaging of biological samples, predominantly providing structural or analyte concentration data in its standard format. Fluorescence lifetime imaging microscopy (FLIM) provides functional contrast, but often at limited acquisition speeds and with complex...

Widefield frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) is a fast and accurate method to measure the fluorescence lifetime of entire images. However, the complexity and high costs involved in construction of such a system limit the extensive use of this technique. PCO AG recently released the first luminescence lifetime imagin...

The quality of image recordings in research and industry depends significantly on the realness and accuracy of the depiction of reality that a given image sensor records. A number of key figures characterize this criterion of quality. Resolution and light sensitivity are often at the center of attention. Wrongly, less attention is usually paid to q...

The luminescence lifetime as a beneficial analytical parameter is known for many years and is well described by a large variety of publications. Many instruments including 2D measuring systems with cameras have been developed and applied in the past years. However, since the current instrumentation to perform either time- or frequency-domain lifeti...

We live in an 8-bit world. Printers and computer screens, and also the human eye, are set to eight bits, i.e., 256 shades of brightness. For many applications however, it is recommendable to work with a wider dynamic range in order to gain more information from an image. But sometimes people complain at camera manufacturers' fair stands because the...

Es gilt bei Fotos und Videoaufnahmen als unerwünscht, dabei ist es nicht nur ein vermeidbares Übel, sondern ergibt sich aus der Natur des Lichts: Bildrauschen. Durch die Wahl der richtigen Kamera für die jeweilige Anwendung lassen sich die Bildstörungen unter Kontrolle bringen. Es kommt dabei nicht auf den Rauschpegel allein an, sondern auf das gew...

Das MuSe-Forschungsprojekt der Bayerischen Forschungsstiftung verfolgt zwei verschiedene Ziele, die es in Zukunft ermöglichen sollen, auf einfache Art und Weise mit Hilfe stationärer und portabler Messsysteme präzise 3D-Modelle zu erstellen, z. B. von historischen Gebäuden. Hierzu sollen die Messdaten stationärer Laserscanner mit den Messdaten eine...

A high-speed, highly sensitive camera is helping biologists at the University of Regensburg in Germany examine how microorganisms move. The researchers selected PCO AG's pco.1600 for the task, based on its image quality. The camera supplements the thermal microscope in observing the archaea, which, despite their small size, are extremely fast. The...

In 2009 a new type of complimentary metal-oxide semiconductor (CMOS) image sensor was developed by a a consortium of three companies: Fairchild Imaging (now a division of BAE Systems), Andor Technology and PCO [1]. At the time the partners decided to call the device a scientific CMOS (sCMOS for short) image sensor to make clear from the very beginn...

A case study reveals that Automatically imaging the ocean and sending real-time pictures back to a base station enables faster panoramic shots for disaster prevention, aerial mapping, and other activities. new camera from the German Aerospace Center (DLR) allows better image new camera from the German Aerospace Center (DLR) allows better image the...

Die Anzahl der Bildpunkte oder Pixel in Bildsensoren ist sowohl bei Fotoapparaten und Handy-Kameras, als auch bei digitalen Kamerasystemen für Messzwecke, wie sie in der industriellen Bildverarbeitung oder in der Forschung zu finden sind, von zentraler Bedeutung. Generell ist der Trend zu höheren Auflösungen erkennbar, weil sie mehr Informationsgeh...

Scientific CMOS oder kurz sCMOS wurde 2009 während der Laser World of Photonics Messe in München von den Firen Andor Technology, Fairchild Imaging und PCO AG als neue Technologie für Bildsensoren vorgestellt. Wie üblich werden neue Entwicklungen als Fortschritt und viel besser als existierende Technologien angepriesen — doch ist diese Technologie w...

A camera-based electroluminescence imaging technique has recently been developed by some researchers from the Nara Institute of Science and Technology in Ikoma. This technique allows a rapid solar cell characterization at high spatial resolution. A cooled charge coupled device (CCD) camera has been used that comes with an IR operating mode to set u...

We used transparent planar oxygen optodes and a luminescence lifetime imaging system to map (at a pixel resolution of <200 μm) the two-dimensional distribution of O2 within the skeleton of a Porites lobata colony. The O2 distribution was closely correlated to the distribution of the predominant endolithic microalga, Ostreobium quekettii Bornet et F...

If images are to be taken in low light, such as in biological or medical applications, microscopy, security or night vision, the camera system's readout noise is an important consideration when making a camera selection. In this case, noise is a bad parameter and should be as small as possible. With large amounts of light, a good signal-to-noise ra...

When digital cameras are used for applications such as stop motion movie creation, machine vision and biotechnology, the images sometimes show strong gradients. This is exhibited as a decrease of the light signal toward the edge of the image. This light fall-off at the edges of an image, known as shading, is caused by lens vignetting and the influe...

We describe the fabrication of organically modified sol–gel (ORMOSIL) planar optodes for mapping the two-dimensional oxygen distribution in sediments. All sensor foils were based on the use of ruthenium(II)-tris-(4,7-diphenyl-1,10-phenantrolin)-perchlorate, which is a fluorescent dye quenched dynamically by oxygen. Sensors made with different sol–g...

Scientific imaging applications require precise data recording and storage. One solution is to shift the memory storage from the PC to the camera itself. This camera memory (camRAM) allows the fastest possible data transfer from the image sensor into memory without loss of information caused by cable conditions or operating system interference. It...

We have developed a fibre-optic microsensor for refractive index measurements and used it with a biological application. It is targeting a refractive index range for aqueous environments between 1.30 and 1.36 and a spatial resolution of below 1 mm. The sensing element consists of a single-ended tapered optical fibre that is coated with a 50 nm gold...

Electron multiplication or charge carrier multiplication CCDs are finding their niche in applications requiring high light sensitivity, high spatial resolution and reasonably high frame rates at either short or long exposure times. The technology uses a conventional readout-node amplifier design but apply gain to the signal prior to readout. This i...

A digital signal processing approach for hybrid fiberoptical microoptodes based on the measurement of the luminescence lifetime of appropriate indicators is presented. Numerical algorithms are applied to resolve individual decay times in a heterogeneous luminescence emission to enable the application of optodes with multiple indicators combined on...

Carbonate sediments are dynamic three-dimensional environments where the surface layers are constantly moving and mixing due to the energy of the water column. It is also an environment of dynamic biological, chemical and physical interaction and modification. The biological community can actively influence changes to sediment characteristics and a...

We describe two applications of a recently introduced system for very precise, continuous measurement of water oxygen saturation. Oxygen microoptodes (based on the dynamic fluorescence quenching principle) with a tip diameter of similar to50 mum, an eight-channel optode array, an intermittent flow system, and online data registration were used to p...

A new signal processing approach for fiberoptical sensors, microoptodes, is presented. All signal generation and processing is completely based on a fast, low-cost DSP (Digital Signal Processor). This enables the implementation of new features such as a simultaneous multi-frequency measurement to resolve different analytical parameters in the lumin...

Due to the modular luminescence lifetime imaging system (MOLLI) that has been developed within the last few years, it is possible to use oxygen sensors that are not optically isolated. Transparent planar optodes and dispersed nano-optodes for the first time enable a direct optical link between the chemical parameter to be measured (oxygen as an exa...

A fiberoptical optode array for the in-situ measurement of ground air oxygen concentrations has been used in both, lab and field experiments to monitor subsurface oxygen consumption in a lignite mine tailing affected by acid mine drainage formation. The single sensors are constructed from plastic fibers (core diameter 1 mm) with an oxygen sensitive...

An improved refractive index microsensor based on surface plasmon resonance (SPR) for fine scale measurements in aquatic environments is presented. Furthermore this sensor should serve as a platform for different applications. In the first place refractive index measurements in marine environments have been performed to characterize the light condi...

A new in situ instrument for two-dimensional mapping of oxygen in coastal sediments is presented. The measuring principle is described, and potential mechanical disturbances, solute and particle smearing associated with the measurements, and calibration routines are evaluated. The first in situ measurements obtained in two different benthic communi...

A new in situ instrument for two-dimensional mapping of oxygen in coastal sediments is presented. The measuring principle is described, and potential mechanical disturbances, solute and particle smearing associated with the measurements, and calibration routines are evaluated. The first in situ measurements obtained in two different benthic communi...

Microscale fluorescence measurements were performed in photosynthetic biofilms at a spatial resolution of 100 to 200 μm with a new fiber-optic fluorometer which allowed four different excitation and emission wavelengths and was configured for measuring phycobiliproteins, chlorophylls, and bacteriochlorophylls. We present details of the measuring sy...

The imaging of two-dimensional (2D) solute distributions with planar optodes has become an important tool in biological and medical research. The development of versatile and flexible imaging systems, that enable both luminescence intensity and lifetime imaging, has generated various applications of planar oxygen optodes. Most of the applied optode...

We present a modular system for time-resolved two-dimensional luminescence lifetime imaging of planar optical chemical sensors. It is based on a fast, gateable charge-coupled device (CCD) camera without image intensifier and a pulsable light-emitting diode (LED) array as a light source. Software was developed for data acquisition with a maximum of...

A new sensor head and imaging application with planar oxygen optodes is presented. It combines the versatility of the recently presented modular luminescence lifetime imaging system (MOLLI) and the oxygen measuring features of planar optodes to investigate the 2D-distribution of oxygen with a high spatial resolution. The marine sediments are settle...

A new refractive index microsensor based on surface plasmon resonance (SPR) for fine scale measurements in aquatic environments is presented. The local light conditions in marine sediments determine the activity of photosynthetic organisms. The light field can be investigated by scalar irradiance microprobes at a spatial resolution better than 100...

Oxygen microopt(r)odes have recently been introduced as an alternative to microelectrodes in the field of aquatic biology. We here describe adaptation, test results and first in situ measurements made with O2 microopt(r)odes on deep-sea benthic landers. This includes a detailed description of the sensors, the mechanical mounting, and the necessary...

We developed a new modular luminescence lifetime imaging system (MOLLI), that enables the imaging of luminescence lifetimes in the range of 1 μs to 1 s. The system can easily be adapted to different experimental applications. The central parts of the system are a recently released CCD-camera with a fast electronic shutter and gated LED (light emitt...

Sediments, microbial mats, biofilms and other microbial communities are characterized by steep gradients of physical and chemical parameters. Fibre optical microsensors, microoptodes, that we developed over the last three years have become powerful tools to investigate and measure these parameters with a sufficient spatial resolution and with a min...

Established sensors for fine scale measurements in natural environments are based on electrochemical measuring principles for e. g. oxygen and pH. The preparation of such electrochemical sensors is, however, a time consuming process. Based on the technical progress in the field of fibre optical measuring techniques many well-known chemical principl...

ISI Document Delivery No.: 107WX

We have developed a simple and mechanically robust fiberoptic microsensor that enables optical detection of the sediment-water interface at a spatial resolution of <50 μm. The sensor measures with a tapered optical fiber the increased backscatter of near-infrared light near the sediment surface. To determine the sediment surface position independen...

Benthic aquatic environments like biofilms or sediments are often investigation by measuring profiles of chemical or physical parameters at a high spatial resolution (< 50 micrometers ). This is necessary to understand e.g. transport processes and the biogeochemistry of the sediment water interface. A variety of electrochemical and optical microsen...

Traditionally microscale measurements of pH are based on potentiometric measurements with a pH glass microelectrode. The preparation of these electrodes is, however, very time consuming. We developed pH micro-optodes for use in seawater in the range of pH 7 - 9. The optodes are based on immobilized acid-base indicators, which change their color and...

A new microoptode array is presented that provides simultaneous measurement with eight oxygen microoptodes using a simple optical setup and a phase-angle detection principle. The measuring system consists of: (1) an optical unit with eight oxygen microoptodes, a special fiber-coupler array, optical filters, lenses, light sources (light-emitting dio...

Sediments, microbial mats, biofilms and other microbial communities are characterized by steep gradients of physical and chemical parameters. Microsensors are powerful tools to measure these parameters with a sufficient spatial resolution and with a small disturbance of the micro-environment in natural systems. Recently, fiber-optical microsensors...

We describe a device capable of imaging distributions of surface PO2 as well as oxygen flux (e.g., into the human skin). Oxygen is monitored by a phase-angle-sensitive imaging technique using the effect of luminescence lifetime quenching of ruthenium complexes incorporated into a polymer layer system. The dyes are excited by modulated radiation of...

The amount of dissolved hydrogen sulfide is an important parameter in many environmental applications. Conventional methods for H2S detection depend on iodometric titration or spectroscopic measurements. Unfortunately these methods are not applicable for direct measurements in natural systems. A recently described method for the on-line detection o...

We developed a noninvasive rapid fluorimetric method for the investigation of growth of adhering (benthic) phototrophic microorganisms. The technique is based on the sensitive detection of the in vivo fluorescence of chlorophylls chlorophyll a and bacteriochlorophyll a and monitors increases in signal over time as an indicator for growth. The growt...

By applying a transparent test membrane of defined diffusion properties between two layers of optical chemical oxygen sensors, O2 optodes, the measurement of oxygen diffusion, the oxygen flux, across the membrane becomes possible.1 The optode has the inherent advantage towards the established method of electrochemical oxygen measurements that the s...

The direct relationship between the oxygen supply by skin blood flow and oxygen uptake (O2 uptake) through the skin could be of importance for the diagnosis of circulatory disturbances and their consequences. A new measuring system has been developed to obtain simultaneously at three places the local O2 uptake throug the skin. It uses the principle...

We present a new fiber-optic oxygen microsensor based on dynamic luminescence quenching which was recently developed for measuring oxygen at high spatial resolution in aquatic sediments and biofilms. Micro-optrodes with a typical tip diameter of 20 to 50 micrometers were fabricated. The fabrication procedure is simple and guarantees a high reproduc...

New fiber optic oxygen microsensors (microoptrodes) for use in aquatic environments have recently been developed as an alternative to commonly used CLark-type oxygen microelectrodes. The microoptrodes have the advantage of no oxygen consumption and no stirring sensitivity combined with a simple manufacturing process of the sensors. To avoid problem...

The development and improvement of oxygen sensors is continuously matter of research because it is important to quantify oxygen concentrations in biological systems. The presented hybrid fiberoptical sensor combines the common advantages of fiber optic sensors e.g. flexible connection to the place of interest and potential separation between place...

About 1-2% of the basal human O2-consumption is taken up by the skin surface. This amount varies depending on the local skin blood flow. A new sensing device, the O2-flux- optode, has been developed which should allow the measurement of local O2-uptake of the skin and thereby indirectly its local circulation. This luminescence-based-sensor (1) is p...