QSI 683WSG 8.3 megapixel, full frame CCD image sensor w/ 8 position filter wheel & off-axis guider
The QSI 683 model camera employs an 8.3mp Kodak full-frame CCD image sensor with microlens technology. The increased Field of View, high quantum efficiency, wide dynamic range, dual read rates, low noise performance and internal 5 or 8-position color filter wheels make the QSI 683 ideally suited to a broad range of demanding scientific, medical, astronomical, and industrial imaging applications.
The compact design of the QSI 600 Series allows the 683 to set a new benchmark for cost and size in a high performance, full-featured scientific CCD camera. With optional features and upgradeability, the QSI 683 can be tailored to fit your needs today and in the future.
The QSI 683wsg is available with an Integrated Guider Port (IGP) allowing astronomers to guide using the light from the main telescope while picking off the light from the guide star in front of the filters.
The 683 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
Large 8.3mp Image Sensor
The large 3326×2504 sensor in the QSI 683, shown to the left approximately life size, provides unprecedented field of view in a camera using standard 1¼” filters.
The compact design and internal color filter wheel of the QSI 683wsg-8 allows unvignetted, filtered images even with optical systems as fast as f/3. The 5.4µm pixel provides extremely high resolution for a high performance CCD.
The KAF-8300 sensor has a photoactive array of 3326W x 2504H pixels. It has excellent quantum efficiency between 350nm and 1000nm with peak QE over 60%. Low dark current and high pixel charge capacity result in a dynamic range exceeding 70db. 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.
Small Light-Weight and Thin
The 600 Series is designed to support image sensors with a maximum diagonal measurement of 22.5mm. For this class of camera they are surprisingly compact. At just 4.45″ square, the Slim body camera is just 1.68″ deep, occupying less than 30 cubic inches and weighing in at under 26 ounces. Even a Full body camera with shutter and color filter wheel is only 2.5″ deep and a mere 40 ounces. In fact, the small footprint is the practical limit for a camera with a 5 position filter wheel using standard 1.25″ threaded or 31mm unmounted filters.
Keeping the depth of the camera to a minimum was an early design goal. Not only is backfocus minimized, 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 backfocus and overall depth. The motion control electronics are actually buried in the 0.12″ 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. Finally, having all electrical cables and the optional liquid heat exchanger recirculation hoses exit the body in the same direction and perpendicular to the optical axis insured an interference-free fit in tight spaces.
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.
The 683ws-8 incorporates a larger 8-position filter wheel. Even with the large 8.3mp sensor, the short backfocus and close spacing provided by the internal color filter wheel allows the 684ws or ws-8 to work even with optics as fast as f/2.8 with no vignetting. 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.
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CCD Image Sensor: KAF-8300
Electronic Shutter: Mechanical, exposure range: 0.03 seconds to 240minutes
Mechanical Shutter: Yes
Internal Color Filter Wheel: Yes 8 position
Camera Body Configuration: Full Enclosure
Optical Back Focus w/o Filters in path: 1.40″ w/ T-mount adapter, 1.18″ w/C-mount adapter, 1.18″ w/ no adapter