The TD900 cold mirror dew point meter is a standard cold mirror dew point meter, mainly suitable for automatic detection of micro water content in general industrial gases. This device uses an industrial micro cooler as the cooling source to assist in cooling, which compensates for the poor performance of traditional cold mirror dew point meters at ambient temperatures above 30 ℃ and the large volume of auxiliary coolers. Based on the fast and stable cooling capacity of a dedicated industrial micro cooler, the equipment adopts a precision inspection type cold mirror measurement method. Compared with traditional balanced measurement methods, this measurement method shortens the measurement cycle while ensuring measurement accuracy, and reduces gas loss during the measurement process.