Thermal Power Sensors are able to detect the optical power of high power sources such as light-emitting diodes (LEDs), filament lamps, and lasers. The Thermoelectric-based sensors, special broadband coatings and low dependency on the angle make these power meters ideal choices for measuring broadband spectra and high power sources. According to the theory of thermoelectric which is based on heat flux, external thermal disturbances can affect thermal power sensor readings so environmental conditions like temperature and airflow should follow the mentioned conditions in the user manual.