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XX1080 MK1 Intensified Camera |
This camera is based on our "periscope 5" military vehicle sight, and provides a highly cost effective solution. The XX1080 intensifier tube requires an external EHT PSU, and has peculiar objective lens requirements. By utilising the vehicle sight in this way, the original PSU and objective lens is retained. It is an additional benefit that the periscope utilises super-fast 50mm F1.0 objective lenses. These awesome front-side optics help to compensate for the losses encountered between the tube and the camera.
Prepare the Periscope
The periscope must first be dismantled. It is necessary to remove the top and bottom prisms, and the eyepieces. Only one of the objective lenses is required, and since these are relatively heavy it makes sence to remove the one which will not be used. It is also a good idea to remove the XX1080 which will not be in use.
The camera
The CCD camera board should be small to fit correctly inside the housing; we used a 32x32mm type. High sensitivity is essential. Unlike the XX1332, the XX1080 has low gain. The camera-tube coupling method shown here is relatively inefficient, and a gain of only 10-15x can be expected. The best results are therefore obtained using the best possible camera, and those based on the Sony Super-HAD technology are the MINIMUM requirement.
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This internal view shows the position of the PCB camera. As space is limited, a small camera is required. The camera lens is a standard 8mm F2.8 type, though something faster would be a significant advantage. A small aluminium bracket supports the camera, which must be held rigidly inside the housing. The depth of focus is only around 1mm, so any subsequent movement of the camera will cause a loss of image clarity.
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Results
This camera was very "experimental", but has provided surprisingly good results. The image clarity is better than expected, and in focus across the whole field, though a little "flaring" is apparent if bright objects enter the edge of the field of view. Stars to magnitude 6 are visible, and the camera is excellent for recording meteor events.
Improvements to this design are not simple to achieve. A high performance coupling lens would be better than the standard PCB camera lens, but this would come with significant cost. Faster front-side objective lenses are not readily available, and any change of lens carries problems due to the curved photocathode of the XX1080. Probably better to look at the XX1332 for your next project!
