Abstract: A cooling device for cooling a detector element disposed in a jacket cavity of a Dewar vessel uses a Joule-Thomson cooler with an expansion nozzle that opens into an expansion chamber. The cooling device includes a final control element that is adjustable depending on temperature for influencing the flow through the expansion nozzle. A first temperature sensor is disposed in the expansion chamber and a second temperature sensor is disposed within the Dewar vessel outside the expansion chamber. The cooling device includes a control device that is configured for detecting a temperature gradient from sensor values of the first temperature sensor and of the second temperature sensor and for adjusting the final control element depending on the detected temperature gradient.

Abstract: A cooling device for cooling a detector element disposed in a jacket cavity of a Dewar vessel uses a Joule-Thomson cooler with an expansion nozzle that opens into an expansion chamber. The cooling device includes a final control element that is adjustable depending on temperature for influencing the flow through the expansion nozzle. A first temperature sensor is disposed in the expansion chamber and a second temperature sensor is disposed within the Dewar vessel outside the expansion chamber. The cooling device includes a control device that is configured for detecting a temperature gradient from sensor values of the first temperature sensor and of the second temperature sensor and for adjusting the final control element depending on the detected temperature gradient.

Abstract: In a multi-element infrared detector a light guide is arranged in front of each detector element, the dimensions of this light guide causing attenuation of radar radiation. Each light guide is formed by a light guiding passage having reflecting and electrically conductive inner walls. The light guiding passages are formed in a passage plate. The surface of the passages are electrically conductive and connected to signal ground. A light stop plate is arranged in front of the passage plate. This light stop plate has light stop apertures in alignment with the light guiding passages. The apertures have non-reflecting inner surfaces. The light stop plate reduces stray radiation.