Time-correlated single photon counting (TCSPC) is a widely used, sensitive, precise, robust and mature technique to measure photon arrival times in applications such as fluorescence spectroscopy and microscopy, light detection and ranging (lidar) and optical tomography. Wide-field TCSPC detection techniques, where the position and the arrival time of the photons are recorded simultaneously, have seen several advances in the last few years, from the microsecond to the picosecond time scale. Here, we summarise some of our recent work in this field with emphasis on microsecond resolution phosphorescence lifetime imaging (PLIM) and nanosecond fluorescence lifetime imaging (FLIM) microscopy.
We discuss a novel micro-channel plate (MCP) photomultiplier with resistive screen (RS-PMT) as a detection device for space- and time-correlated single photon counting, illustrated by several applications. The photomultiplier tube resembles a standard image intensifier device. However, the rear phosphor screen is replaced by a ceramic “window” with resistive coating. The MCP output is transferred through the ceramic plate to the read-out electrode (on the air side) via capacity-coupling of the image charge. This design allows for an easy reconfiguration of the read-out electrode (e.g. pixel, charge-sharing, cross-strip, delay-line) without breaking the vacuum for optimizing the detector performance towards a certain task. It also eases the design and manufacturing process of such a multi-purpose photomultiplier tube. Temporal and spatial resolutions well below 100 ps and 100 microns, respectively, have been reported at event rates as high as 1 MHz, for up to 40 mm effective detection diameter. In this paper we will discuss several applications like wide-field fluorescence microscopy and dual γ/fast-neutron radiography for air cargo screening and conclude with an outlook on large-area detectors for thermal neutrons based on MCPs.
We have developed single photon counting image intensifier tubes combining position and time information read-out with at least 500x500 pixels and sub-nanosecond time resolution. This image intensifier type uses a resistive screen instead of a phosphor screen and the image charge pickup anode is placed outside the sealed tube. We present a novel delay-line anode design which allows for instance detecting simultaneously arriving pairs of photons. Due to the very low background this technique is suited for applications with very low light intensity and especially if a precise time tagging for each photon is required. We show results obtained with several anode types on a 25 mm image intensifier tube and a 40 mm open-face MCP detector and discuss the performance in neutron radiography, e.g. for homeland security, and the prospects for applications like Fluorescence Life-time Imaging Microscopy (FLIM), astronomy and X-ray polarimetry.
We have developed image intensifier tubes with delay-anode read-out for time- and position-sensitive photon
counting. The timing precision is better than 1 ns with 1000x1000 pixels position resolution and up to one megacounts/s
processing rate. Large format detectors of 40 and 75 mm active diameter with internal helical-wire delay-line anodes
have been produced and specified. A different type of 40 and 25 mm tubes with semi-conducting screen for image
charge read-out allow for an economic and robust tube design and for placing the read-out anodes outside the sealed
housing. Two types of external delay-line anodes, i.e. pick-up electrodes for the image charge, have been tested. We
present tests of the detector and anode performance. Due to the low background this technique is well suited for
applications with very low light intensity and especially if a precise time tagging for each photon is required. As an
example we present the application of scintillator read-out in time-of-flight (TOF) neutron radiography. Further
applications so far are Fluorescence Life-time Microscopy (FLIM) and Astronomy.
We have investigated the full three dimensional momentum correlation between the electrons emitted from strong field double ionization of neon when the re-collision energy of the first electron is on the order of the ionization potential of the singly charged neon ion. We find that the momentum correlation in the direction perpendicular to the laser field depends on the time difference of the two electrons leaving the ion. Our results are consistent with double ionization proceeding through transient double excited states that field ionize.
We present results on novel image intensifier tubes for single photon detection. We have adopted an image charge coupling technique that allows a read-out of image intensifiers with good imaging properties and much superior time resolution than obtainable with the standard phosphor screen read-out. Although combinations of sealed microchannel plate detector tubes with position and time sensitive anode structures have already been reported, our method has the advantage that the superficial electrode array has not be implemented inside the tube. We couple the image charge from a high-resistive anode layer through the vacuum housing to a wedge-and-strip or delay-line pattern that can be attached from outside. We show results on single photon imaging with special intensifiers produced by Proxitronic GmbH in the visible and UV for an active diameter of 25 mm. The variability of the system, especially a version with a solar-blind UV-cathode and 40 mm active diameter, should open great opportunities for detection task in various fields like astronomy, reconnaissance, bioluminescence, atomic physics, and material research, particularly when both good imaging and timing performance are required.
Based on delay-line read-out methods of micro-channelplate (MCP) stacks we develop imaging system for single particle and photon spectroscopy. A complete system consists of an open MCP-detector with helical wire anode, specially designed front-end electronics and a stand alone PC-based TDC-system. We achieve a position resolution better than 0.1 mm and excellent linearity for open dimensions up to 100 mm, multi-hit operation, and detection rates up to 20 kiloEvents/sec in an event-listing mode or over 1 MegaCount/sec in a histogram mode. Both modes allow 2D position and time-of-flight (TOF) spectroscopy with approximately 1 nanosec TOF resolution. Furthermore, we currently test a delay-line anode on printed circuit that operates with image charge pick-up from a high-resistive collecting anode. With an image charge detection method this 3D-imaging technique can be applied to commercial sealed MCP single-photon detectors. While a simple high-resistive collection anode is placed inside the tube, a position sensitive pick-up electrode can be mounted next to it outside the vacuum wall.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.