The Ultimate in Scientific ICCD Technology
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Technical Note IMAGING GROUP emICCD: The Ultimate in Scientific ICCD Technology Single-Photon Detection Capability and <500 psec Time Resolution With the rapid expansion of research in areas such as nanotechnology, quantum computing, and combustion, the development of higher-performance time-gated cameras is becoming a necessity. This technical note describes the latest breakthrough in scientific intensified CCD (ICCD) technology: the world’s first emICCD. © 2013 Princeton Instruments, Inc. All rights reserved. Current Technologies: ICCDs and EMCCDs In ICCD cameras, ultra-low-light detection is achieved by high amplification of incoming photons by an intensifier (see Figure 2). Time resolution is possible due to the fact that the intensifier can be switched on and off (gated) in very short intervals. Electrical Connection Rings Princeton Instruments’ new emICCD technology combines the benefits of an intensifier and an electron-multiplying CCD (EMCCD) in order to deliver single-photon detection capability and <500 psec time resolution.* This innovative technology, available exclusively in the renowned Princeton Instruments PI-MAX®4 camera platform (see Figure 1), is ideal for a broad range of applications, including fluorescence lifetime imaging microscopy (FLIM), combustion, planar laser-induced fluorescence (PLIF), photon counting, and time-resolved imaging and spectroscopy. Photocathode Microchannel Plate Incident Light Intensified Image Figure 2. Cross-section view of an image intensifier tube utilized in a Princeton Instruments ICCD camera. Figure 1. The new Princeton Instruments PI-MAX4:512EM is the first scientific camera on the market to utilize revolutionary emICCD technology. The intensifier consists of a photocathode, a microchannel plate (MCP), and a phosphor screen. A fraction (the quantum efficiency, or QE) of the photons incident on the photocathode is converted into electrons. Single photoelectrons are converted into clouds of electrons by the MCP, which acts as a distributed electron multiplier. The electrons released from the MCP then strike the fluorescent screen (phosphor) and cause it to emit far more photons than were incident on the photocathode. In the traditional ICCD configuration, the voltage between the photocathode and the input of the MCP is used to switch the intensifier on and off. If the photocathode is electrically

IMAGING GROUP biased more positively than the MCP, electrons will not enter the MCP and the intensifier is gated off. If the photocathode is negatively biased, electrons will be accelerated toward the MCP and the intensifier is turned on. Traditional EMCCD technology, meanwhile, does not use an external intensifier. An EMCCD enables multiplication of charge (i.e., electrons) collected in each pixel of the detector’s active array. Secondary electrons are then generated via an impact-ionization process that is initiated and sustained when higher-than-typical clock voltages (up to 50 V) are...

IMAGING GROUP emICCD Notes Optimized between two gains Spurious Noise Yes, but lower than EMCCD Minimum Exposure Susceptibility to Bright Light Photon-Counting Capability System Gain Using lower EM gain Table 2. Performance comparison of emICCD technology, ICCD technology, and EMCCD technology. of ICCDs and the electron multiplication gain and high quantum efficiency of back-illuminated (optional) EMCCDs, allowing researchers in areas such as combustion, ultra-lowlight chemiluminescence imaging, quantum optics, and timeresolved imaging and spectroscopy to design experiments hitherto not...

IMAGING GROUP Precision: emICCD EMCCD Groundbreaking emICCD technology offers researchers an unprecedented combination of precision, true single-photon detection, intelligence, and speed. Its precision performance is evidenced by superior linearity. Fiber coupled Lens coupled Figure 4. The PI-MAX4:512EM utilizes fiberoptic coupling, which offers higher light throughput and a better signal-to-noise ratio than lens coupling. The importance of high linearity is demonstrated in Figure 5, where different species from exhaust gas residue (CO, NO, C2, OH, etc.) are studied under different...

IMAGING GROUP Brightfield Image Photon-Counting Mode True Single-Photon Detection: emICCD Higher sensitivity is another important advantage of emICCD technology. These new cameras utilize, for the first time, an EMCCD fiber-coupled to either a Gen II or Gen III intensifier and are capable of true single-photon detection. The benefit of photon counting is readily apparent in Figure 6, where the accumulation of a large number of frames with thresholding yields a higher-contrast image (i.e., better signal-to-noise ratio) compared to an image captured using a traditional ICCD camera with high...

IMAGING GROUP Figure 8. New Princeton Instruments PI-MAX4:512EM camera operating in kinetics mode with 512x20 pixel window, running at >800 fps. (If the movie does not start automatically, please click on the image.) Intelligence and Speed: emICCD Impressive intelligence is another hallmark of Princeton Instruments’ new emICCD cameras. Sophisticated yet intuitive LightField software* provides an oscilloscope-like user interface (see Figure 7) that allows dynamic control of gains, intensifier gate widths, and gate delays, while automatically keeping track of experiment setups, users, etc....