For optimum detector performance and system interface
Application of input cooler power generates heat in a TE cooled detector. To avoid damage, the TE cooled detector should be mounted securely on an adequate heat sink. The heat must then be dissipated through the bottom of the package header and the external heat sink. The entire bottom surface of the header (excluding the feedthroughs) must be in intimate thermal contact with a flat mating surface area of the heat sink where a non-conductive thermal compound has been applied. For optimum performance, a copper or aluminum heat sink, capable of dissipating at least twice the input cooler power, should be used.
A temperature controller/power supply is necessary to stabilize and control the operating temperature of a TE cooled detector over a range of ambient system temperatures. The detector must contain a thermistor, and the controller should be designed so that the thermistor is in a tight servo loop with the amplifier in the controller. After careful consideration of the TE cooler capability, heat sink temperature, and the anticipated range of ambient temperatures (See TE cooling section above) the resistance value of the set point resistor can be chosen. Input power to the TE cooler should be from a d.c. supply with less than 10% ripple.
Preamplifiers for either PbS or PbSe detectors must accommodate high input impedance and provide a low noise, low impedance interface to the system electronics. They must provide the desired gain, frequency response, and be stable over the ambient temperature range. To minimize noise, preamplifiers should be designed with a low frequency cut off, reduced microphonics, and protection against electro magnetic interference (EMI).