The standard direct radiation sensor is used to measure the radiation perpendicular to the sun’s surface and the diffuse radiation around the sun. It has the function of automatically tracking the sun and monitoring the direct radiation of the sun. The sensor is mainly composed of a light cylinder and an automatic tracking device. The inner part of the optical cylinder is composed of seven light bars and inner cylinders, quartz glass, thermopile and desiccant cylinder. The seven light barrier is used to reduce the internal reflection, form the open angle of the instrument and limit the turbulence of the air inside the instrument.
Outside the light barrier, the inner cylinder is used to seal the dry air inside the light rail and the outer cylinder to reduce the influence of the ambient temperature on the thermopile. JGS3 quartz glass is installed on the cylinder, and it can radiate directly through the 0.3-3 m wavelength. The end of the barrel is equipped with a desiccant to prevent condensation of water vapor.
The sensing part is the core component of the optical cylinder. It is composed of a fast response wire wound electroplated multi-node thermopile. The sensing part facing of the sun is coated with an American 3M black paint, which is a thermal junction of the thermo electric reactor. When the sun is exposed, the temperature rises, and it forms a temperature difference electromotive force with the other cold junction. The electromotive force is proportional to the intensity of the solar radiation.