Author: Tom Droege Date: 980518 (18 May 1998) Key Words: CCD, instrumentation, hardware
This note shows the camera hardware in pictures.
Figure 1 shows ten sets of head major parts as received from the vendor. Cost about $3000 for those who are interested. About $300 per camera. Starting with the parts with the zig-zag water channel, there is the back cooling plate. The CCD is glued to the front surface of this plate (not shown). Water passing through the channel cools the CCD. To the upper left of the water plate is the return shutter bracket. Above are the spacer rings that space the front plat which mounts the shutter from the rear cooling plate. to the immediate right of the cooling plate are the spacers that fit between the thermo electric cooler (TEC) and the CCD. To the far right is the front mounting ring. The shutter brackets mount to the front mounting ring. Above and to the right of the front mounting ring are the shutter brackets that mount the shutter drive motor. Below and to the right are the plates that seal the zig-zag water channel. To their left are the lens mounting rings. The lens mounting rings are threaded for a 40 mm diameter "t" thread and take standard "t" thread to camera lens adaptors.
Figure 2 is the assembled camera opened up. To the left can be seen the assemble front enclosure including the camera ring, and the shutter mounted to the front mounting ring. A Canon adaptor is shown screwed into the front mounting plate. This in turn is attached to the camera ring with four machine screws. To the right is the printed circuit board attached to the cooling plate. The CCD is shown mounted in its socket. Thermal compound and slight screw pressure keeps the CCD in good thermal contact. The camera head is made as thin as possible. The CCD actually sticks up inside the shutter opening to get it as close as possible to the front camera surface.
Figure 3 shows the camera turned over on its face to show the wiring. There are two connectors and three 1/4" tubing fittings. The larger connector is a standard DB-25 connector. A PC parallel cable can be used up to 100'. These are cheap as they are in high production. Thin cable of high resistance can be used since the cable carries little current. A second DB-9 cable provides the current to the CCD. The cable shown uses 4 ea. #22 wires in parallel for both the forward and return path. This will be satisfactory in most cases. The camera will draw 1-2 amps of TEC current. Two of the 1/4" pipe fittings carry the cooling water to and from the camera. The third is attached to a container of desiccant with a short length of tubing.
Figure 4 is a side view of the assembled camera head with an attached 135mm focal length, f/2 Canon lens. The TV remote is there for size comparison. We do not plan it as the camera control system.
Figure 5 is a view of the camera head showing the shutter servo pulley and string arrangement. The strings connect to a parlor door shutter. The shutter opening is 1.6" square, more than covering the 1.2" square CCD.
Figure 6 is a head on view of the camera head. In this view, the camera head seems to hide almost completely behind the lens. The shutter servo motor can be clearly seen.
Back to Index of Technical Notes
Back to TASS home page
