An infrared radiation detector includes: a cryostat having a cold finger ensuring heat exchange with a cold source and a window transparent to infrared radiation to be detected; a mechanically fixed cold plane in heat exchange with the cold finger; a detector unit comprising at least a detector circuit sensitive to the infrared wavelength range to be detected, and in direct or indirect heat exchange with the cold plane; and a mechanically fixed cold shield in heat exchange with the cold plane and limiting stray radiation. The cold shield is rotationally symmetrical. An inside wall of the cold shield has a succession of reliefs distributed in at least one helical pattern. A definition axis of the helical pattern coincides with the axis of revolution of the cold shield.