The QSI-6162 model camera model employs a KAF-16200, 16 megapixel, full frame CCD image sensor with microlens technology that has been specifically produced for astrophotography. The 6-micron pixel size make this camera the ideal imaging partner for a wide range of focal length telescopes. The ability to ‘bin’ the CCD means the QSI-6162 is suitable for focal lengths right up to 2.5m and still stay around 1 arc second per pixel (recommended for successful imaging). The large APS-H 16mp CCD sensor with a 35mm diagonal works happily using 2” mounted or 50.8 mm unmounted filters on scopes as fast as f/2.8 with minimal vignetting. The camera is available with or without an Off-Axis Guider and the choice of a five or eight position filter wheel.
The ‘ws’ model comes with a shutter and filter wheel installed. The ‘wsg’ model is supplied with the Off-Axis Guider, Integrated Guider Port (IGP).
The 6162 camera system is supported by industry leading image acquisition software plus a full camera control API is available for creating custom Windows or Linux applications.
- High Performance CCD Image Sensor
- Leading Edge Technical Performance
- Refined Design
- Efficient, Low Power CCD Sensor Cooling
- Compact shutter and Filter Wheel
- Innovative Integrated Guider Port
- Connectivity and Notification
- Comprehensive Software Support
Large 16 Megapixel CCD Image Sensor
The 6162-model camera employs an On Semiconductor KAF-16200 16-megapixel full-frame CCD image sensor. The KAF-16200 sensor has a photoactive array of 4490 W x 3599 H pixels. Low dark current of 8e- and a 40,000e- well depth. Micro lenses cover the surface of the CCD to focus the light through the transparent gate to further increase the optical response of the sensor. The 6 µm sized pixels provides extremely high resolution at long focal lengths and superb wide field images at short focal lengths.
The sensor employs a true two-phase charge transfer technology with a transparent gate that significantly increases optical response compared to traditional front illuminated full frame sensors.
The KAF 16200 sensor has excellent response values between 400nm and 1000nm with peak QE over 58%. Low dark current and high pixel charge capacity result in a dynamic range exceeding 69db. Micro lenses cover the surface of the CCD to focus the light through the transparent gate to further increase optical response. See the Specifications tab below for more detail.
High Performance Design
“The QSI 600 Series was designed from the ground up to attain the highest possible imaging performance from Kodak’s Full-Frame and Interline Transfer CCD image sensors.”
Two separate analogue processing chains, providing dual read rates, allow the QSI 600 Series to meet two seemingly incompatible imaging goals. The QSI 600 Series High Quality mode provides the highest possible Signal to Noise Ratio (SNR) for applications that require the lowest noise and widest possible dynamic range. High Speed mode has a read rate of 8MHz providing high speed reads at multiple frames per second. The read mode is easily changed under program control providing exceptional flexibility it tuning the camera’s performance to the desired imaging goals.
All significant performance characteristics, including Linearity, Read Noise, and Photon Transfer (Gain), are tested and confirmed during manufacture. Each camera’s timing and voltages are carefully set during manufacture to ensure maximum Charge Transfer Efficiency, and to minimize charge injection and other secondary noise sources. QSI’s exclusive Research Spec® profiling ensures optimal performance in every camera.
Sophisticated mixed-signal design practices are utilized throughout the camera. This permits a very compact design while eliminating interference from conducted and radiated noise. ROHS compliant multi-layer circuit boards and surface-mount components are used exclusively. A unique circuit board stacking methodology eliminates interconnecting wires that could reduce reliability.
A carefully designed and isolated switching power supply generates all of the voltages needed to operate the camera from a single 12VDC power source. Low noise design practices and advanced filtering techniques completely eliminate any measurable impact on camera noise performance.
Arguably, the most important aspect of a CCD camera design is the video processing subsystem. This is where almost all of the camera’s performance characteristics are established. The 600 Series video processing begins with a very low noise, precision preamp to accurately amplify the microvolt level pixel signal from the CCD image sensor. This signal is then processed through a Correlated Double Sampler (CDS) to reduce temporal read noise in the pixel signal. Subsequent signal conditioning then feeds the pixel level to a high-speed, precision 16-bit Analog to Digital Converter (ADC) where it is converted to a digital value between 0 and 65535.The Read Noise contributed by this entire subsystem is exceedingly small. So small in fact, that it is virtually undetectable, contributing less than 1/30 of the combined read noise of a typical KAF image sensor. The low read noise and carefully chosen camera gain yield excellent Dynamic Range. Linearity is also outstanding, limited only by the CCD image sensor itself.
Innovative, Aesthetic Body Design
The new large format QSI 6162 sets new standards for full-featured, high performance scientific CCD cameras. The striking appearance, refined design and superior fit and finish only hint at the advanced technical performance inside. Some have described it as a work of art.
A defining feature of the 600 series camera is the flexible design that permits progressively configured body styles with a minimal impact on the overall size. The new 6162 case builds on this modular approach by adding an optional Off Axis Guider to the ‘ws’ style case without having to replace the whole case front as in the past. This helps to provides a cheap and easy upgrade path not available before with QSI cameras.
Engineered with extensive use of sophisticated CAD – CAM design tools, the QSI 6162 is machined from 6802 grade aluminium alloy. The finely finished anodized body components are assembled with corrosion resistant stainless-steel hardware throughout.
Keeping the depth of the camera to a minimum was an early design goal. The traditional short back focus measurements of the existing QSI 600 series cameras have been maintained with the design of the 6162. Not only is back focus minimized throughout the range, but the camera moment-arm is reduced resulting in greater stability. The shutter and filter wheel were placed inside the body, very close to the image sensor reducing back focus and overall depth. The motion control electronics are actually buried in the 3 mm thick shutter/filter mounting plate to reduce depth further. Pulling the cooling fans and heatsinks into the body resulted in another significant reduction in depth.
CCD Cooler Subsystem
Key in the design of the 6162 Series cameras is a very efficient custom 2-stage thermoelectric cooler (TEC) subsystem. Intelligent, programmable cooling fans are integrated into the rear of the camera body to remove the heat generated by the cooler. Typically, forced air cooling lowers the regulated CCD temperature by up to 45°C below ambient utilizing 85% power. Tight +/- 0.1°C temperature regulation is maintained at temperature settings of 10°C below ambient and lower.
The cooled CCD image sensor is positioned in a hermetically sealed environmental chamber covered with an anti-reflection coated precision optical window. The chamber is purged with an ultra-dry noble gas to increase heat conduction and eliminate the possibility of frost forming inside the chamber. To extend the useful period before re-purging is required, a user-rechargeable microsieve desiccant is employed to scavenge water molecules that enter the chamber. It is located behind a sub-micron, gas-permeable membrane to prevent particulate contamination of the CCD chamber.
Cooling and Dark Current
Effective cooling of the CCD image sensor is essential for long exposure imaging, especially in astronomy. Thermally generated electrons accumulate in the pixels over time and compete with the photo-electrons that make up the image. This accumulation of thermal electrons is known as ‘dark current’. It lowers the dynamic range of the sensor and reduces the signal to noise ratio. Eventually the thermally generated electrons will swamp the image.
Fortunately, dark current can be reduced dramatically by cooling the CCD. Onsemi CCD sensors accumulate thermal electrons at a rate of roughly 4 electrons per second per pixel at 25°C. With every 6.3°C decrease in temperature the dark current is reduced by half. Where a 10-minute exposure might generate 2400 thermal electrons at 25°C, it will produce only about 10 at -25°C. This is a very small number when compared to the CCD read noise and pixel full well capacity.
Shutter and Filter Subsystem
The 6162 camera achieves its unique configuration flexibility though an innovative shutter/filter subsystem. Both the mechanical shutter and filter wheel can be installed internally while keeping the growth of the camera dimensions at a minimum. This results in minimal loss of back focus as these features are added. The compact design also reduces vignetting with fast optical systems.
Shutter and Filter Wheel
The Model 6162ws camera incorporates QSI’s proprietary internal, even-illumination mechanical shutter and adds an internal five or eight position filter wheel to the camera. The filter wheel accepts any standard threaded 2″ or unmounted 50.8 mm filters. The filter wheel can be easily removed and replaced to change or clean the glass filters. Additional filter wheels can be purchased allowing quick interchange of different filter set configurations. The shutter is not only used for timing exposures, but can be left closed to produce ‘dark frames’ for subsequent image processing. Exposures can be as short as 0.03 seconds or as long as 240 minutes. The shutter is rated for more than 1 million cycles.
Integrated Guider Port
Selecting the best guiding solution for deep sky imaging has always required a compromise. The optional available Integrated Guider Port (IGP) solves many of the problems associated with existing guiding solutions.
The Right Guiding Solution
Guiding with a separate guide scope provides the most flexibility, but differential flexure can be an issue, especially with long focal length scopes. With an internal guide chip, you’re forced to guide with light through your filters and you can’t guide at all while the shutter is closed or an image is being downloaded. This is especially problematic for narrowband imagers. To get around those issues, you could add an external off-axis guider, but a traditional OAG can add an inch or more of back focus plus more weight and two new mounting surfaces that need to be held rigidly.
Guide with Light from in Front of the Filter Wheel
The QSI 6162wsg model solves the problems with other guiding solutions by integrating a Precision Off-Axis Guider directly into the camera body with the pick-off prism positioned in front of the integrated color filter wheel – right where it belongs.
Never Struggle with Finding a Guide Star
One of the main challenges when using a camera with an internal guide chip is to find a star bright enough to guide by within the limited field of view of the internal guide sensor. When shooting through red, green or blue filters, ⅔ of the available light is blocked by the filter and not transmitted to the internal guider chip, guaranteeing lower signal-to-noise stars for guiding. This problem is compounded with narrowband filters where as little as 1% of the total light from a star reaches the guide chip. By positioning the pick-off prism in front of the filters, you always have all the star’s light available for guiding.
Integrated Guide Port Supports Fast Optical Systems
By integrating the Off-Axis Guider into the camera, we’re able to position the pick-off prism very close to the internal filter wheel adding minimal back focus and eliminating any possibility of flexure or rotation compared to a traditional OAG. The large ½” square pick-off prism is optimally positioned close to the internal filter wheel, supporting the use of guide cameras with large sensors, while preventing any vignetting of the main sensor even with very fast optical systems.
Flexible Guide Camera Options
The optional Integrated Guide Port (IGP) when installed on the 6162ws models is designed to support any camera with 12.5mm of back focus or less that can be attached using C-mount, STi mount or T-mount threads. Many cameras are designed with 12.5mm of back focus to be compatible with CS-mount lenses. CS-mount lenses use the same thread as C-mount (1″ x 32tpi) but with 12.5mm of back focus as opposed to 17.5mm for C-mount.
Easy, Rigid Guide Camera Focusing
The guide camera attaches to the OAG using a C-mount, Sti mount or T-mount threaded adapter (specified at time of order). The threaded adapter sits on top of the focus ring and allows the guide camera to be rotated to any position. The focus ring threads onto the focus base to allow 3mm of travel when focusing the guide camera. Once focus is achieved, the focus ring is locked with a set screw. The guide camera can still be rotated manually if desired without changing the focus. The end result is a rigid, easily focused guide camera that will not move or flex while your mount tracks the apparent motion of the night sky.
The connector panel, shown above, is thoughtfully recessed into the body of the camera for protection and provides access for all external connections. The two threaded holes on the back of the body are used to attach an optional cable restraint system to support the electrical connections.
The 6162 utilizes a High-Speed USB 2.0 port (USB 1.1 compatible) for connection to the host computer and imaging application software. Read and transfer time for an entire 16 mp image frame is typically approximately three second in High Speed mode and twenty three seconds in High Quality mode. The frame rate can be further increased by reading just a portion of the image (ROI) or with flexible on-chip binning.
A four channel optically isolated control port is accessible through a standard 6 pin modular connector. The signal pin-out is compatible with most modern telescope mount drive correctors and is intended to be used for telescope guiding with a suitable control program such as PHD2, Maxim DL and similar.
The outputs can also be used for other control purposes when developing your own applications with the 600 Series ActiveX software development toolkit. The outputs are common emitter, open-collector and can sink up to 50ma. The maximum voltage should not exceed 50v.
One of the defining features of the 6162 is power efficiency. A fully configured 6162 camera operates from a single 12v DC supply and consumes less than 36 watts at full cooling, with both fans at maximum and the filter wheel moving. Included with each camera is an approved 12-volt DC power supply with an input voltage range of 90-240V, 50-60HZ.
Both visual and audible notification is built into the 6162 cameras. A multi-color LED status display provides visual indication of the various states of camera operation. The behaviour of the indicator is configurable and can be disabled by user command. A unique internal beeper provides audible feedback of camera operation and status. Like the visual display, the beeper can be configured and disabled by the user.
Every 600 Series camera is accompanied by a collection of software applications and tools that allow you to begin imaging immediately or develop custom camera control applications to precisely match your requirements.
Many other popular astronomical imaging packages are also support. See the QSI Software page for complete details.
Windows Custom Application Development
QSI provides an ASCOM-compatible API (Application Programming Interface) enabling customers to write their own custom camera control applications. The camera control API is an automation component that communicates with the camera device driver and exports a COM automation interface. COM automation provides an interface which Microsoft Office, VB, VBA, C++, and other Windows applications can use to control the camera. The API is available as part of the QSI Software Development Kit (SDK), available for download from the QSI website.
ASCOM Learn more about the ASCOM Initiative. ASCOM website
Using the Windows COM API with LabVIEW, MATLAB and other applications
The QSI camera control Windows API is an automation component that communicates with the camera device driver and exports a COM automation interface. The COM automation interface allows custom camera control applications to be developed for use with National Instruments LabVIEW, MathWorks MATLAB and any other application that adhere to the Windows COM interface. The API is distributed on the QSI Installation CD and is included with the QSI USB Drivers and Software installer above. The API Reference Manual can be downloaded from the documentation page. QSI has sample VI’s for LabVIEW that can be used as a starting point to develop custom LabVIEW applications. Please contact QSI Support for details.
Linux Custom Application Development
QSI provides a camera control C++ API for Linux users on Intel x86-compatible platforms. The API provides full camera control and image capture capabilities via the USB interface. The API is implemented as a shared library providing an easy to use camera object that exposes all of the features and capabilities of the camera. It is well suited for both simple scripting, and more sophisticated imaging application development.
Model QSI-6162 Specifications
|Sensor Type||CCD – KAF-16200|
|Horizontal Resolution||4499 pixels|
|Vertical Resolution||3599 pixels|
|Pixel Size||6 µm x 6 µm|
|Readout Noise||8e- typical value high quality mode|
|Gain Factor||High gain and low gain modes|
|Dark Current||>0.25 electrons/second at 0°C|
|Interface||USB 2.0 high speed|
|Power||12v DC 3.5A|
|Maximum Exposure Length||Unlimited|
|Minimum Exposure Length||50 ms|
|Cooling||Thermoelectric set point with max ΔT -50°C|
|Download speed||High speed 3 seconds
High quality 23 seconds
|Weight: approx.||2.9 kg for wsg-8
2.8 kg for ws -8
OAG weight 0.15kg
|Dimensions||5 pos: 189 x 189 x 87.5mm
8 pos: 238 x 238 x 87.5mm
|Back Focus||30mm ws model 50mm wsg (without adapters)|
|Adapter threads currently||M54
M68 internal with 3” eyepiece adapter
2.75” internal thread with 3” eyepiece adapter
|In the box||Power adaptor
USB drive with software