Application of the blackbody radiation source for characteristics measurement of submillimeter low-temperature direct detectors

As is well-known characteristics measurement of submillimeter low-temperature direct detectors can be fulfilled using their signal response for the radiation of temperature swept blackbody. We describe a method using the Fredholm integral equation of first kind which solution gives possibility to derive direct detector spectral characteristic from the signal response dependence on temperature with acceptable accuracy. Then a noise equivalent power of detector can be determined as well.