PURPOSE: An apparatus for measuring the temperature inside the chamber using a pyrometer is provided to minimize the occurrence of process variable and the extension of process time due to the irreproducibility of the measured temperature by precisely measuring the internal temperature of the GaAs ingot growing apparatus using the pyrometer. CONSTITUTION: A pyrometer(4) is installed on the outside of a chamber. The pyrometer is an apparatus for measuring the temperature using the infrared ray. A heater(5) and a heat insulator(6) are installed on the inside of the chamber. A viewport is made to measure the internal temperature of the chamber. A structural apparatus made of the graphite is installed between the viewport and the heater.
