The theoretical research of the background irradiation of an IR array with the specific cold shields A. I. Patrashin Orion R&P Association, 46/2 Enthuziastov road, Moscow, 111123, Russia E-mail: orion@orion-ir.ru The theoretical research of the background irradiation of an IR array with three types of the cold diaphragms is executed. <...> This research is necessary for the design of optimized IR array photodetector. <...> First two types of the diaphragms are standard, and the third — is offered the author. <...> It is shown that the background irradiation has useful and parasitic component. <...> Useful component defines the value of the signal and the sum of the useful and the parasitic components together with the array dark current — size of the device noise. <...> For this reason, the calculation of their values is necessary for the correct calculation of IR array photo-electric parameter. <...> The comparative component analysis is carried out for the specified types of diaphragms. <...> Представлено теоретическое исследование фоновых облученностей матрицы фоточувствительных элементов (МФЧЭ) с тремя типами холодных диафрагм, необходимое при разработке матричных фотоприемных устройств (МФПУ). <...> Первые два типа являются стандартными, а третий — предлагается автором. <...>