The Cookbook CCD Camera
The Cookbook CCD camera is a build it yourself system. The primary advantage is a cost savings with the added benefit of gaining an understanding of the camera's internal workings. The instructions and software are contained in the book by R. Berry, V. Kanto and J. Munger. Working with this camera has been a great experience. I have learned quite a bit.
The authors encourage experimentation with the design after a "by the book" working camera is achieved. This is sound advice. Being someone who by nature is unable to leave a good design alone, I did not. A reading of the archive of the CCD mail list produced several ideas by different folks. Scott Kroeger suggested a simple Cross Talk Modification that permits the use of a long cable between the camera head and the PC interface. My camera carries all signals and power to the camera on one 25 wire data grade cable. The cooling system draws considerable amperage and several conductors were ganged together to carry this load. The cooler produces a measured Delta T of 45 degrees C.
Here is a picture of the camera head and the power supply/PC interface box. These are thumbnail pics. Click on it to see a larger version and user your browser's BACK button to return.
The power supply and interface circuit fit quite nicely within an old metal case that came with a portable drill. The interface circuit is shielded from the the power supply EMF by an additional aluminum enclosure. AC input power is filtered by a EMF filter from an old PC power supply that provides a handy connector for the power cord.
The camera head has the heat exchanger rotated 180 degrees to move the cooling lines away from the preamp enclosure. The picture shows the camera with the excellent manual filter wheel produced by Andy Saulietis. Attached to the front of the filter wheel is a T thread to SCT thread adapter and a 2 inch nose piece. I turned these from some scrap T6 aluminum. Chuck Shaw gave me the idea to dimple the points where the filter wheel thumb screws clamp the front of the camera. This permits precise realignment when the camera and filter wheel are separated to insert an IR blocking filter for color work.
My preamp runs without the Q7 buffer transistor. This transistor is prone to thermal drift and a software solution was implemented to compensate for it. I just did not like watching the drift. Al Kelly thermally stablizes his preamp with an old sweat sock. Others have use various types of foam to insulate the transistor. At the same time Q7 was removed, the gain on the second stage amp was recalibrated. This is a good idea anyway after the Low Dark Current modification. My camera now goes into a non-linear response at around 3700 PV.
This was measured using a modified Al Kelly style light box. There are four small "grain'o wheat" bulbs that indirectly illuminate an opaque screen. I used an adjustable voltage regulator and a pot to provide a repeatable and changable level of illumination. It produces very nice flat fields for image calibration.
The original design used a windshield washer pump to circulate the coolant in a closed loop. Several alternatives emerged to the rather noisy WW pump. Some folks found a submersable aquarium pump to be a good solution. I have had good luck with a small bilge pump designed for boats. It runs on 12 volts and will tolerate being run dry and it is very quiet. The system is an open loop cooling system consisting of a 5 gallon bucket filled with tap water at a temperature above the dew point or potable (non toxic) RV antifreeze when the weather is cold.
Liquid cooling has the advantage of being very stable over time and still working well despite a high ambient air temperature. The high end commercial CCD camera are now offering it as an option. The down side is the bucket, tubes and pump, not to mention the liquid itself.
Updated 7/30/00
