Generally, R-HEED operate only in ultra-high vacuum (UHV) conditions due to the nature of electrons. However, a relatively high oxygen partial pressure (High Pressure) environment is essential for growing high-quality oxide thin films on PLD. The High Pressure RHEED, developed to perfectly resolve this contradiction, utilizes differential pumping technology. It is designed to safely maintain an ultra-high vacuum inside the electron gun while maintaining high oxygen pressure within the chamber where the thin film grows. This allows for real-time (in-situ) monitoring of the oxide thin film growth process, ensuring that the moment is not missed.