TBS-2C Direct Radiometer Light Tube

Product Introduction

The TBS-2C Direct Radiometer (also known as a Pyrheliometer) is a professional instrument used to measure Direct Normal Irradiance (DNI), which is the solar radiation received per unit area perpendicular to the sun's rays. It is widely applied in meteorology, solar energy utilization, agricultural ecology, and other fields. Below are its key features: The direct radiometer specifically measures the irradiance of direct solar beams, i.e., the solar energy per unit time incident on a unit area perpendicular to the sun (unit: W/m²). Its field of view is typically 5°±0.2°, capturing only the solar disk and a narrow annulus of circumsolar sky radiation. When the direct solar irradiance is ≥120 W/m², it can also be used to calculate sunshine duration (actual sunshine hours).

The direct radiometer requires an automatic solar tracking device for operation and is a passive product that does not require separate power supply.

Our company's direct radiometer is developed based on the "GB/T 37468-2019 Direct Radiometer" standard. Its structure consists of seven apertures, an inner tube, quartz glass, a thermopile, and a desiccant cartridge. The seven apertures are designed to reduce internal reflection, define the instrument's opening angle, and limit internal air turbulence. Outside the apertures is the inner tube, which encloses dry air inside the apertures and the outer tube to minimize the impact of ambient temperature on the thermopile. A JGS3 quartz glass window is mounted on the tube, transmitting solar direct radiation in the wavelength range of 0.3~3μm. The end of the optical tube contains a desiccant to prevent moisture condensation.

The sensing element is the core component of the optical tube, consisting of a fast-response wire-wound electroplated multi-junction thermopile. The sensing surface facing the sun is coated with US 3M matte black paint, where the thermopile's hot junctions are located. When sunlight irradiates the surface, the temperature rises, creating a thermoelectric electromotive force (EMF) between the hot and cold junctions. This EMF is proportional to the solar radiation intensity, as per the formula: E = U / S, where S is the calibration sensitivity.

Technical Parameters