A shutter assembly may be provided for an infrared imaging module to selectively block external infrared radiation from reaching infrared sensors of the infrared imaging module. For example, the shutter assembly may comprise a paddle situated external to an optical element (e.g., lens) and adapted to be selectively moved by an actuator to substantially block external infrared radiation from entering the optical element. The shutter assembly may be stacked relative to a housing of the infrared imaging module without excessively increasing the overall profile of the infrared imaging module. A substantially reflective low emissivity interior surface may be provided on the paddle to reflect infrared radiation originating from an infrared sensor assembly of the infrared imaging module back to the infrared sensor assembly.