Scientific CMOS (sCMOS) Technology: An Overview
By Ron Grunsby, Editor
Introduced in June 2009, scientific complementary metal-oxide-semiconductor (sCMOS) technology is based on CMOS image sensor design and fabrication techniques and offers several advantages over previous CMOS- and charge-coupled device (CCD)-based sensors for many applications.
In general, CCD-based cameras offer high sensitivity but slow sampling speeds. Conventional CMOS cameras offer very fast frame rates but compromise dynamic range. sCMOS image sensors, on the other hand, offer extremely low noise, rapid frame rates, wide dynamic range, high quantum efficiency, high resolution, and a large field of view simultaneously in one image. This makes them particularly suitable for high fidelity, quantitative scientific measurement and low-light-level conditions. Specific performance parameters vary from camera to camera. Please see the sCMOS imaging solutions below for these specifics.
Pixel structure along with the merging of signal paths enables all these features to come together in one sCMOS image sensor. A unique architecture of dual-level amplifiers and dual 11-bit analog/digital converters helps maximize dynamic range and minimize readout noise at the same time by analyzing and merging them into one high-dynamic 16-bit value.
“sCMOS technology as originally presented was very unique compared to what was out there at the time,” said Steve Daicos, president of PCO-TECH Inc. (formerly The Cooke Corporation). “Customers were compromising, using CCDs for a lot of applications but also using CCDs to get speed. Tradeoffs existed. With sCMOS technology, we recognized we could build cameras that could produce all those features simultaneously — that’s where we saw the potential.”
Andor Technology, Fairchild Imaging (part of BAE Systems), and PCO worked together to develop sCMOS technology and announced its launch on June 16, 2009. They also released a white paper at the time detailing the technology.
Applications for sCMOS imaging abound in the life sciences and many other areas and include:
|
|
For more background information about sCMOS technology, please check out the following articles:
New sCMOS vs. Current Microscopy Cameras
Q&A: 7 Key sCMOS Imaging Questions Answered
New Thinking About Scientific Cameras
sCMOS Imaging Solutions
Following is a selection of sCMOS imaging solutions. Click on the product names or related links for additional specifications. For more information on these or other sCMOS imaging solutions, please contact us.
The ORCA-Flash4.0 scientific CMOS camera from Hamamatsu Corporation offers high sensitivity with high quantum efficiency (over 70% at 600 nm) and low noise (1.3 electrons). It has a 100-fps (frames per second) readout at full resolution and up to 25,600 fps with a small region of interest. The 4.0-megapixel Gen II scientific CMOS image sensor allows for a 2.5x larger field of view than that of a standard electron multiplying charge-coupled device (EMCCD) camera, and much finer details can be resolved with the 6.5- x 6.5-µm pixel size. Hamamatsu has developed a white paper that details why they believe the ORCA-Flash4.0 redefines sCMOS.
“Because this camera has a unique combination of high quantum efficiency and low noise in the absence of multiplicative noise (inherent to EMCCD technology), it outperforms EMCCDs for almost all fluorescence applications. EMCCDs still have the advantage for extremely low light experiments that have no background signal like luminescence,” Mark Hobson, marketing manager for scientific cameras at Hamamatsu, told Photonics Online.
According to Hobson, it is primarily the high quantum efficiency of the Gen II sCMOS that makes it possible to outperform EMCCDs.
Hamamatsu had previously developed the ORCA-Flash2.8 sCMOS camera.
In the video below, Jessica Uralil of Hamamatsu Corporation highlights several new technologies, including the ORCA-Flash4.0.
The OSPREY scientific CMOS camera from Raptor Photonics boasts a 4.2-megapixel scientific CMOS sensor that enables large field-of-view imaging, TE cooling down to -20°C to optimize dark current, quantum efficiency >64% at 610 nm and >35% at 845 nm for optimum photon collection, active pixel size of 5.5 µm x 5.5 µm for ultra-sharp image resolution, 12-bit Camera Link output, high-frame-rate imaging up to 37.5-Hz full frame for capturing fast events, and an ultra-compact size of 86 mm x 65 mm x 61 mm.
“In terms of performance, OSPREY is very similar to other sCMOS cameras in the market, but is only a fraction of the price,” said Olivier Bernard, director of sales and marketing at Raptor Photonics. “Thanks to the rugged design, it can be operated in extreme environmental conditions, from -20°C to +55°C. This is why the camera is better suited to the life science instrumentation OEM market. Other camera manufacturers have opted for high-end performance for the single end-user market.”
Raptor entered the sCMOS market in response to requests from some of their OEM customers to develop a cost-effective, rugged, compact sCMOS camera.
The pco.edge sCMOS camera from PCO-TECH Inc. features low readout noise of 1.1 electrons (e-) med, better than 27,000:1 dynamic range, 5.5-megapixel resolution, a frame rate of 100 fps at full resolution of 2560 x 2160 pixels, stabilized Peltier cooling (+5°C) that allows for continuous operation free of any drift phenomena in image sequences, and quantum efficiency >54% at peak.
“To better understand the performance of the pco.edge, compare it to a 1.3-megapixel scientific CCD (Sony ICX285AL) camera, which typically features a readout noise of 6 e- at a full frame rate of 10 fps,” said PCO-TECH’s Daicos. “In contrast, the pco.edge sCMOS camera features <2 e- readout noise at a resolution of 1.3 megapixels and a frame rate of 210 fps. In this specific example, the benefits are higher speed and reduced readout noise.”
The pco.edge is well-suited for a wide range of applications in life science, physical science, industry (machine vision), and broadcasting. The development of a back-illuminated version is under consideration.
In the video below, Murad Karmali discusses the features of several PCO-TECH cameras, including the pco.edge.
The Tau CNV from FLIR Systems is a rugged, compact, low-power CMOS HD camera for ultra-low-light, video-rate imaging applications. It uses Fairchild Imaging’s sCMOS sensor with 6.5-μm2 pixel pitch and 1280 x 960 resolution, ultra-high 25,000:1 dynamic range, and <2 e- (rms) read noise.
“Our main focus is on night vision applications – our target audience is primarily security and defense OEMs,” said Art Stout, VP of business development, FLIR Systems Advanced Imaging Systems Division. “We anticipate this technology will also be useful in other commercial markets, including machine vision.”
The Tau CNV is configurable with 1280 x 960 and 1280 x 720 (720p) resolution at 30 fps. Interface options include Camera Link, NTSC analog, or 3.3 V LVCMOS parallel, and it can be purchased with or without the integrated motorized IR-cut filter. It is available in color and monochrome versions.
FLIR has the Tau CNV 1080P in development, with a launch expected late in the third quarter of 2012. Resolution will be 1920 x 1080. Unlike the Tau CNV, which has a rolling shutter, the Tau CNV 1080P will have a global shutter, which is needed by electro-optics customers who can’t use a rolling shutter.
The CIS1021 sCMOS sensor from Fairchild Imaging (part of BAE Systems) can capture images at speeds up to 100 fps at full resolution, five times faster than the typical scientific imaging rate of 20 fps. It offers more than 88 dB of intrascene dynamic range, captures images in a 1920 x 1080 HDTV format, and is available in a monochrome or color version.
The CIS1021 is part of the Fairchild Imaging high-performance sCMOS family of sensors (and cameras derived from those sensors). The unique features of the sCMOS sensor family include ultralow readout noise (<2 e- rms), very high intrascenic dynamic range (greater than 15,000:1), and very high-speed operation (100 fps at full resolution).
Looking ahead to the future, Mark Christenson, business development manager at BAE Systems, said: “We can envision further enhancements in the area of lower noise, higher dynamic range, higher net quantum efficiency, and perhaps higher speed. We also have had some requests for a lower-cost product based on sCMOS as well. We always look to input from our users as to the desired features and formats that we should produce, so we would encourage those with interest to contact us and let us know their needs.”
The video below features the CIS1021.
The Rolera Bolt from QImaging is capable of streaming at 30 full fps with 1.3-megapixel resolution and 3 e- read noise and can be used for tracking high-speed dynamic events with detailed spatial and temporal resolution. It features Pixel-Freeze Technology that reduces dark current to nearly undetectable levels, eliminating the need for an expensive Peltier cooling system. This makes a lightweight, compact design with minimal power requirements possible, which allows the Rolera Bolt to use a single USB 2.0 connection for both power and 12-bit data transfer.
“We used a smaller 1.3-megapixel sensor. Bioresearch uses microscopes taking images of cells and individual proteins, so by using a smaller field of view, we can stop the data from being too big to handle,” James Schumacher, president of QImaging, explained.
One of the things that makes the Rolera Bolt unique is its affordability – according to Schumacher, it can be had for less than half the cost of most scientific CMOS and CCD cameras.
“QImaging isn’t a company that just invents new scientific imaging technology – we take high-end performance and make it available to the masses,” said Schumacher. “With the economy down and scientific research being cut back, we wanted to make scientific CMOS capabilities available at a low price point.”
In the video below, Chris Ryan of QImaging talks about the Rolera Bolt.
The xSCELL digital scientific camera from PHOTONIS USA offers 1000 fps at a resolution of 1024 x 1024 pixels while providing read noise of <2 e- rms. xSCELL is powered by a proprietary CMOS-based InXite sensor, which delivers data at a high dynamic range up to 14 bits and is cooled internally to -30ºC to render the effects of dark noise to negligible levels. Peak quantum efficiency approaching 65% makes this camera particularly suitable for low-light applications.
“With our sensor, we can get similar read noise as the other companies’ products at 10 times the speed — 1000 fps while the others are at 100 fps,” said Marc Neglia, director, imaging products, PHOTONIS USA.
PHOTONIS USA is targeting scientific applications in which users can exploit the frame rate, such as super-resolution microscopy.
“In this technique, researchers are taking many frames and reconstructing them at a resolution far beyond the resolution afforded by the pixel size of the camera,” Neglia said. “It takes millions of images to reconstruct this data and reproduce it at a much better resolution. You get to the end result 10 times faster, at 1000 fps vs. 100 fps.”
Andor Technology’s sCMOS camera family consists of two camera platforms, Neo and Zyla, each designed around the same 5.5-megapixel sensor. Zyla, launched in April 2012, is a very light (1 kg) and compact sCMOS camera that lends itself well to both OEM and research usage. It is cooled to a stable 0°C at up to 35°C ambient and is available in enclosed or board-level formats, with private labeling also offered. Zyla is extremely fast, offering a sustained 100 fps through a dual Camera Link “10-tap” interface. There is also a cost-effective 30-fps “3-tap” version.
Neo is vacuum-cooled and designed for minimum noise and maximum sensitivity. With 1 e- read noise as a starting point, Neo’s deep cooling down to -40°C further suppresses the influence of dark noise over a wide range of exposure conditions. Both Neo and Zyla offer rolling and global/snapshot shutter exposure mechanisms that are user-selectable within the software.
“Our experience in the scientific imaging market has taught us that image quality is extremely important at any camera price point,” said Dr. Colin Coates, product manager – imaging, at Andor Technology. “CMOS technology carries considerable optimization challenges in yielding images of sufficient quality, uniformity, and quantitative stability, and Andor has put enormous effort into the real-time camera intelligence required to execute this.”