MHz Pixel Rate Research Articles

Single pulse two photon fluorescence lifetime imaging (SP-FLIM) with MHz pixel rate.

Two-photon-excited fluorescence lifetime imaging microscopy (FLIM) is a chemically specific 3-D sensing modality providing valuable information about the microstructure, composition and function of a sample. However, a more widespread application of this technique is hindered by the need for a sophisticated ultra-short pulse laser source and by speed limitations of current FLIM detection systems. To overcome these limitations, we combined a robust sub-nanosecond fiber laser as the excitation source with high analog bandwidth detection. Due to the long pulse length in our configuration, more fluorescence photons are generated per pulse, which allows us to derive the lifetime with a single excitation pulse only. In this paper, we show high quality FLIM images acquired at a pixel rate of 1 MHz. This approach is a promising candidate for an easy-to-use and benchtop FLIM system to make this technique available to a wider research community.

Design of current mirror integration ROIC for snapshot mode operation

Current mirror integration (CMI) read out integrated circuit (ROIC) topology provides a low input impedance to photo-detectors and provides large injection efficiency, large charge handling capacity and snapshot mode operation without in-pixel opamps. The ROIC described in this paper has been implemented with a modified current mirror circuit, with matched PMOS pairs for detector input stage and its biasing. The readout circuit has been designed for 30 × 30 μm2 pixel size, 4 × 4 array size, variable frame rate, 5 Mega pixel per second (Mpps). Experimental performance of the test chip has achieved 15 Me charge handling capacity, a high dynamic range of 83 dB, 99.8% linearity and 99.96% injection efficiency. The ROIC design has been fabricated in 3.3 V 1P6M UMC 180 nm CMOS process and tested up to 5 MHz pixel rate at room and at cryogenic temperature.

Simulations of charge transfer in Electron Multiplying Charge Coupled Devices

Electron Multiplying Charge Coupled Devices (EMCCDs) are a variant of traditional CCD technology well suited to applications that demand high speed operation in low light conditions. On-chip signal amplification allows the sensor to effectively suppress the noise introduced by readout electronics, permitting sub-electron read noise at MHz pixel rates. The devices have been the subject of many detailed studies concerning their operation, however there has not been a study into the transfer and multiplication process within the EMCCD gain register. Such an investigation has the potential to explain certain observed performance characteristics, as well as inform further optimisations to their operation. In this study, the results from simulation of charge transfer within an EMCCD gain register element are discussed with a specific focus on the implications for serial charge transfer efficiency (CTE). The effects of operating voltage and readout speed are explored in context with typical operating conditions. It is shown that during transfer, a small portion of signal charge may become trapped at the semiconductor-insulator interface that could act to degrade the serial CTE in certain operating conditions.

Programmable gain amplifier with colour balancing for CCD image sensors

The authors present a new programmable gain amplifier (PGA) with colour balancing for single-chip CCD colour image sensors. The PGA with synchronised gain switching allows higher SNR to be achieved in the amplified image while maintaining sufficient gain resolution and low power dissipation. A floating-point expression is used in the designed five-stage pipelined PGA for compact and low-power implementation. Low-noise gain switching with a cross-coupled ring counter sufficiently suppresses the pattern noise due to the high-speed gain switching. The power consumption is 119 mW at 3.3 V supply voltage and 20 MHz pixel rate.

100 kV field emission electron optics for nanolithography

A 100 kV optics with field emission source is designed for an electron-beam nanolithography system. A new electrostatic gun lens permits high-voltage operation with low aberrations. A demagnifying double-lens column with fixed magnification and variable aperture is used. The optics are weighted towards 100 kV operation, but the beam voltage can be varied from 25 to 100 kV with resolution maintained below 20 nm. The gun uses a Zr/O/W<100≳ cathode operated near the extended-Schottky emission regime to achieve 1%/h current stability at a fixed extraction voltage. With the source emitting a 0.5 mA/sr angular intensity, 1.5 nA can be focused to 6 and 10 nm with beam voltages of 100 and 50 kV, respectively. A target current density of 2000 A/cm2 with an effective brightness of 1×108 A/cm2 sr enables 2 MHz pixel rate exposures of PMMA at 100 kV with a vector-scan deflection system.

Fsem: Fast Scanning Electron Microscopy

Commercially available SEM‘s offer a maximum “TV” framing rate of ∼30 Hz. We have obtained a digitally-acquired framing rate of 381 Hz with submicron resolution [1]. This is at a 25 MHz pixel rate, compared with the ≤4 MHz video bandwidth of TV-rate machines. We have also performed analog-acquired experiments at effective framing rates of 4.9 kHz and effective pixel rates of >50 MHz. Our present detection and recording system is capable of 200 MHz pixel rates, with reduced contrast range at higher rates. Extrapolating current technology suggests that GHz pixel rates with useable final image signal-to-noise ratios are possible [2].In large part, the success of electron microscopy is due to: the high resolution possible with the small de Broglie wavelength of even keV electrons, small effective electron source diameters, and small optical aberrations of well-designed electron optics. With this resolution, SEM also attains large depth of focus with scanned, narrow electron beams. SEM micrographs are generally noted for exceptional sharpness and large depth of focus. The highest quality micrographs require scan times of tens of seconds or more.

Hardware for real-time image processing

The system described here is a real-time edge detector for use in image processing. The edge-detection algorithm is a 2 × 2 Roberts product, thresholded with a function of the local average brightness. The hardware is designed to work at 10 MHz pixel rate, and will accommodate images of 512 × 512 pixels at 25 frames/s with noninterlaced video, or of up to 512 × 290 pixels with interlaced scanning. The hardware is pipelined and paralleled to achieve the required speed. The output from the system is a one-bit-per-pixel edge picture. This is transferred directly into the memory of the host computer for further processing.