Detector devices for receiving light and generating electrical signals, including a housing and a detector, often exhibit a noise-inducing, temperature-dependent dark current. Such a dark current can be reduced by cooling.
The German Patent Application DE 10 2009 036 066 A1 discusses an optoelectronic detector that has a cooling device, namely a Peltier element, that is thermoconductively connected to the detector. To prevent condensation water from forming on a surface of the optoelectronic detector, a sensor is provided for determining an instantaneous value of the ambient air humidity and of the ambient dew point temperature. The sensor is connected to a control unit that controls the cooling device as a function of the value. It is advantageous that this optoelectronic detector does not dispense altogether with a cooling. However, the actual cooling capacity is disadvantageously limited to low levels, namely to levels at which no condensation water forms. Detector noises are, therefore, not effectively prevented.
The same publication mentions another detector device where the detector, together with the cooling device, typically a Peltier element, is encapsulated in an airtight housing that is filled with a dry gas or is evacuated. In the case of this device, the waste heat can be transferred to a heat sink that is thermoconductively connected to the cooling device, and/or be used for heating other components, such as an entrance aperture of the housing. However, this detector device is recognized as being disadvantageous because of the costly air-tight encapsulation.
In practice, it actually turns out that other disadvantages are associated with this detector device. In particular, the cooling is often not very effective. Moreover, the cooling proves to be especially problematic when the detector is required to be at a different electric potential level than the housing. In such a case, the Peltier element cannot be readily configured between the housing and the detector. Such a potential difference is mostly necessary when photoelectrons are to be accelerated within the detector.