Scientific CMOS

Scientific complementary metal-oxide-semiconductor (Scientific CMOS or sCMOS, pronounced "s sea moss"), is a scientific image sensor technology based on on next generation CMOS Image Sensor (CIS) design and fabrication techniques. Over the past few decades, and from a scientific standpoint, the performance of ‘traditional’ CMOS imagers has generally been considered to be inferior to that of Charge Coupled Device (CCD) technology and their acceptance into scientific markets has been limited due to a reputation of unacceptably high read noise and darkcurrent, lower fill factors and greater non-uniformity. These are drawbacks that sCMOS technology has been designed to overcome.
Launched on June 16 2009 by Andor Technology (UK), Fairchild Imaging (USA) and PCO (Germany), sCMOS technology carries a set of advanced performance features that make it suitable to high fidelity, quantitative scientific measurements . The technology is distinct in its ability to circumvent the performance trade-offs that are more commonly associated with other imaging detector types, both CMOS and CCD. sCMOS can simultaneously deliver low read noise, rapid frame rates, wide dynamic range, high pixel resolution and a large field of view.
The first sCMOS sensor carries the following set of performance specifications:
• Sensor format: 5.5 megapixels (2560(h) x 2160(v))
• Read noise: < 2 e- RMS @ 30 frames/s; < 3 e- RMS @ 100 frames/s
• Maximum frame rate: 100 frames/s
• Pixel size: 6.5 μm
• Dynamic range: > 16,000:1 (@ 30 frames/s)
• QEmax.: 60%
• Read out modes: Rolling and Global shutter
Technical Details
The primary technical advancements that underlie sCMOS technology remain proprietary, however some of the architectural details of the first 5.5 megapixel sensor have been published.
The sensor features a split readout scheme in which the top and bottom halves of the sensor are read out independently. Each column within each half of the sensor is equipped with dual column level amplifiers and dual analog-to-digital converters (ADC). This architecture was designed to minimize read noise and maximize dynamic range simultaneously.
The dual column level amplifier/ADC pairs have independent gain settings, and the final image is reconstructed by combining pixel readings from both the high gain and low gain readout channels to achieve a wide intra-scene dynamic range from such a small pixel pitch. Each pinned-photodiode pixel has 5 transistors ("5T" design), enabling the novel "global shutter" mode (described in more detail below) and also facilitating correlated double sampling (CDS) and a lateral anti-blooming drain.
The sensor is integrated with a microlens array that serves to focus much of the incident light per pixel away from the transistors and onto the exposed silicon, enhancing the QE (analogous to use of micro lenses in interline charge-coupled devices to focus light away from the column masks).
The sensor is configured to offer low dark current and extremely low read noise with true CDS. Non-linearity is less than 1% and is further correctable to < 0.2%. The sensor also has anti-blooming of >10,000:1, meaning that the pixels can be significantly oversaturated without charge spilling into neighboring pixels.
It is also possible to use the anti-blooming capability to hold all or parts of the sensor in a state of "reset", even while light is falling on these pixels. The time to transfer charge after the exposure is complete is less than 1μs, rendering the sensor useful for fast electronic shuttering and "double exposure" techniques such as Particle Imaging Velocimetry (PIV).
Applications
The advanced feature set of sCMOS means that it will contribute to improvements across a wide spectrum of applications and techniques. Uses of sCMOS detection technology include:
Live cell microscopy - Particle Image Velocimetry (PIV) - Single Molecule Detection - Super resolution microscopy - TIRF microscopy / waveguides - Spinning disk confocal microscopy - Genome sequencing (2nd and 3rd gen) - Fluorescence Resonance Energy Transfer(FRET) - Fluorescence recovery after photobleaching (FRAP) - Bio- & Chemi Luminescence - Lucky astronomy / imaging - Adaptive optics - Solar astronomy - Spectral (hyperspectral) imaging - Fluorescence spectroscopy - High-content screening - Photovoltaic inspection - X-ray tomography - Ophthalmology - Flow cytometry - Biochip reading - Machine vision - TV / Broadcasting - Laser Induced Breakdown Spectroscopy (LIBS)

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