QSI RS .40

0.4 Megapixel CCD Image Sensor

The standard RS 0.4 model camera employs a Kodak KAF-0402ME 0.4 megapixel Enhanced Response full-frame CCD image sensor with microlens technology. The KAF-0402ME sensor has a photoactive array of 1536W x 1024H pixels. It has excellent quantum efficiency between 350nm and 1000nm with significant enhancement at the blue end of the spectrum. Peak QE approaches 80%. Low dark current and high pixel charge capacity result in a dynamic range exceeding 76db.

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. 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 for more detail.

An alternate CCD configuration is optionally available. The KAF-0402E image sensor does not include micro lenses but is otherwise identical to the standard image sensor. The chart above illustrates the difference in quantum efficiency between these CCD imager sensors. The KAF-0401LE is no longer available.

High Performance Design

“The QSI RS Series was designed from the ground up to attain the highest possible imaging performance from Kodak’s Full-Frame and Inteline Transer CCD image sensors.”

Two separate analog processing chains, providing dual read rates, allow the QSI RS Series to meet two seemingly incompatible imaging goals. The QSI RS 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 exclusiveResearchSpec® 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 RS 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.

CCD Cooler Subsystem

Key in the compact design of the RS 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. A slim liquid heat exchanger (shown at right) can be attached to the rear of the camera body to increase the cooling further, up to 55°C below the temperature of the circulating fluid.

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. Kodak 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 RS Series achieves its compact size and 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 backfocus as these features are added. The compact design also reduces vignetting with fast optical systems.

Shutter

The Model RS 0.4s camera incorporates QSI’s proprietary internal, even-illumination mechanical shutter in the ‘mid-size’ camera body configuration. 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.

Exposures can be fired under software control or with the use of the hardware input trigger.

Filter Wheel

The Model RS 0.4ws adds an internal five position filter wheel to the camera in a ‘full-size’ camera body. The RS 0.4ws-8 incorporates a larger 8-position filter wheel. The filter wheel accepts any standard threaded 1.25″ or unmounted 31mm 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 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 as well as the recirculation hoses if the liquid heat exchanger is employed.

USB Interface

All QSI RS Series cameras utilize High Speed USB 2.0 port (USB 1.1 compatible) for connection to the host computer and imaging application software.

Guider/Control Port

A four channel optically isolated control port is accessible through a standard 6 pin modular connector. Two of the signals are used to control the input and output shutter triggers.

For telescope guiding the signal pin-out is compatible with most modern telescope mount drive correctors. The outputs can also be used for other control purposes when developing your own applications with the RS 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.

Power Requirements

One of the defining features of the RS Series cameras is power efficiency. A fully configured 640ws camera operates from a single 12v DC supply and consumes less than 24 watts at full cooling, with both fans at maximum and the filter wheel moving. Other camera model configurations have power consumption as low as 5 watts. Included with each camera is an approved 12 volt DC power supply with an input voltage range of 90-240V, 50-60HZ.

Notification

Both visual and audible notification is built into all RS Series cameras. A multi-color LED status display provides visual indication of the various states of camera operation. The behavior 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.

Comprehensive Software Support

Every RS 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.

MaxIm LE and MaxIm DL 

MaxIm LE is based on the award winning MaxIm DL version 4.5 from Diffraction Limited providing the fastest and easiest way to image the night sky. All QSI RS Series cameras are supported for imaging and auto-guiding, plus most popular guider cameras are supported as well. MaxIm LE is available with any RS Series camera. You can upgrade to MaxIm DL/CCD for an attractive price at the time of purchase.

Drivers for Software Bisque’s CCDSoft and TheSkyX

Realizing that one shoe doesn’t fit all, QSI also supplies the necessary drivers for CCDSoft, the popular Image Processing and Camera Control Software from Software Bisque, as well as their latest imaging application, TheSkyX.

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.

 Learn more about the ASCOM Initiative.

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.

Field Upgradeable Firmware

All RS Series cameras can be upgraded to the latest firmware in the field. The latest firmware is always available for download from the QSI Software page. QSI supplies a simple fail-safe Updater application that handles all the details.