US Patent 11536567 Surveying instrument

A surveying instrument comprises a light projecting optical system for projecting a distance measuring light to a predetermined measuring point, a light receiving optical system for receiving a reflected distance measuring light and an infrared light from the measuring point, and an arithmetic control module for controlling a distance measurement and a temperature measurement based on light receiving results of the reflected distance measuring light and the infrared light, and the arithmetic control module measures a distance to the measuring point based on light receiving results of the reflected distance measuring light received by a photodetector of the light receiving optical system, and measures a temperature of the measuring point based on light receiving results of the infrared light received by a temperature sensor of the light receiving optical system.