where TD is the detector temperature. The effective absorbed power is also dependent on the geometric configuration of the incident radiation. In the present experiment, the area of blackbody source was much larger than that of the detector area. Therefore, in this type of convergent geometrical configuration, cosine corrections need to be applied to the effective incident radiation [24]. It is important for light and solar radiation sensors to include a cosine correcting head to eliminate measurement errors which may arise when the light source (usually the sun) is not directly above the sensor, but at any angle within the hemisphere of measurement. Hence, Eq. (3) will be modified as