Multiport-readout frame-transfer 5 megapixel CCD imaging system for TEM applications

Area of Science:

• Electron Microscopy
• Digital Imaging Technology
• Solid-State Physics

Background:

• Intermediate-high-voltage electron microscopy (IVEM) requires advanced digital imaging systems for high-resolution analysis.
• Existing systems may have limitations in readout speed and sensitivity at higher electron energies.

Purpose of the Study:

• To develop and test a novel multiport-readout, frame-transfer charge-coupled device (CCD) digital imaging system for IVEM applications up to 400 keV.
• To evaluate the system's performance characteristics, including readout speed, sensitivity, and spatial resolution.

Main Methods:

• Development of a digital imaging system utilizing a back-thinned CCD with 2560 x 1960 pixels (24 µm x 24 µm pixel size).
• Implementation of a multiport readout architecture using four of eight on-chip ports in parallel, operating at 1- or 2-MHz pixel rates.
• Utilized frame-transfer readout as an electronic shutter for simultaneous integration and readout.
• Incorporated a thin film-based phosphor screen and lens relay for electron-to-digital signal conversion.

Main Results:

• Achieved a full CCD array readout time as short as 0.6 seconds.
• Demonstrated a conversion factor of 2.1 digital units per incident electron at 400 keV.
• Measured a modulation transfer function (MTF) of 14% at the Nyquist frequency, indicating good spatial resolution.

Conclusions:

• The developed multiport-readout, frame-transfer CCD system is suitable for IVEM applications up to 400 keV.
• The system offers rapid image acquisition and good performance characteristics for high-voltage electron microscopy.
• This technology advances digital imaging capabilities in high-energy electron microscopy.