The QSI 683ws-8 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 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 683ws-8 can be tailored to fit your needs today and in the future.
The large 3326×2504 sensor in the QSI 683ws-8, shown to the left approximately life-size, provides an unprecedented field of view in a camera using standard 1¼” filters.
The compact design and internal color filter wheel of the QSI 683ws-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.
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.
CCD Cooler Subsystem
Key in the compact design of the 600 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 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 600 Series achieves its compact size and unique configuration flexibility through 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
The Model 683ws-8 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.
Filter Wheel
The Model 683ws-8 adds an internal eight-position filter wheel to the camera in a ‘full-size’ camera body. Even with the large 8.3mp sensor, the short back focus and close spacing provided by the internal color filter wheel allow the 683ws-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. 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 to 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 600 Series cameras utilize 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 8.3mp image frame is typically approximately one second in High-Speed mode and less than 12 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.
Guider/Control Port
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 under MaxIm/DL and CCDSoft. 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, and open-collector, and can sink up to 50ma. The maximum voltage should not exceed 50v.
Power Requirements
One of the defining features of the 600 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 600 Series cameras. A multi-color LED status display provides a visual indication of the various states of camera operation. The behavior of the indicator is configurable and can be disabled by the user command. A unique internal beeper provides audible feedback on camera operation and status. Like the visual display, the beeper can be configured and disabled by the user.
SKU: qsi683ws-8
