Specialized Camera Technology

High-performance imaging devices need specialized camera systems that will operate the unique features of these devices and will not degrade their inherent low-noise performance.

The Advanced Imaging Technology program area has built numerous camera systems able to operate the devices it has designed and fabricated. Here we show two examples: a Space Surveillance Camera and a Four-Sample High Speed Camera.

The Space Surveillance Camera is used in an operational system to track and classify satellites in low Earth orbit. This 1 m diameter telescope has also been used with a similar camera to discover and track asteroids that might intersect Earth’s orbit under the Lincoln Near-Earth Asteroid Research (LINEAR) program.

Figure 1. The Space Surveillance CameraFigure 1. The Space Surveillance Camera
is the black tube mounted to the telescope.

The camera is the black tube shown mounted to the telescope in Figure 1. This CCD camera system replaces a legacy Vidicon-based system that has been used since the 1970s, and so the space available is predetermined. Therefore, in addition to high performance and low noise, the camera form factor was constrained and, furthermore, needed to be easily accessible for field maintenance.

The camera that was designed to meet these requirements is modular with full digital control of all important trim parameters, since access to the camera in its operational configuration is difficult.  

Figure 2. Side view of Space Surveillance Camera with case removedFigure 2. Side view of Space Surveillance Camera with case removed.

Figures 2 and 3 show side views of the camera with the case removed. Each card shown has a different specific function in the camera. Note that a vacuum pumping port also needs to share the space within the cylindrical envelope of the camera case. Figure 4 gives a view of the device mounted behind the vacuum view window.

 

Figure 3. View of other side of the Space Surveillance Camera with case removedFigure 3. View of other side of the Space Surveillance Camera with case removed.

 

 

 

 

 

 

 

 

 

Figure 4. View of the device mounted Figure 4. View of the device mounted
behind the vacuum view window.

The camera designed for the Four-Sample High-Burst-Rate CCD device is another example of a very specialized camera. This device also operates at cryogenic temperatures, has constraints on the space available to mount components, and must operate in several modes with low noise, as the Space Surveillance Camera system above. An additional feature of this system is the electronic shutter, which is an integral part of the operation of the four-sample CCD. This shutter requires a high-speed pulse (<50 ns rise time) with 8 V amplitude which drives a relatively large capacitance on the 5 cm × 5 cm size CCD.

The camera electronics driving the electronic shutter needed to be designed carefully in order to achieve the speed inherent in the device itself. We have built a cryostat-based camera (cold head shown in Figure 5) capable of meeting the expected performance.  The multiple feed-throughs near the device were necessary to limit the resistance to enable fast rise and fall times of the shutter pulse driving the large capacitance load of the electronic shutter CCD.

Figure 5. Cold head of four-sample high-speed camera. Left, view with vacuum window removed. Right, side view. Note the multiple vacuum electrical feed-through posts for driving the electronic shutterFigure 5. Cold head of four-sample high-speed camera. Left, view with vacuum window removed. Right, side view. Note the multiple vacuum electrical feed-through posts for driving the electronic shutter.

 

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