Laizhong LDT402A

　　Sichuan Surveying and Mapping Instrument Company introduces the theodolite Laizhong LDT402A to you:

　　Theodolites are divided into electronic and optical theodolites based on the difference in dial scale and reading methods.In China,optical and electronic theodolites are mainly used,while vernier theodolites have long been eliminated.

　　The horizontal and vertical dials of optical longitude and latitude are made of glass,and evenly spaced scribes are engraved on the surrounding edges of the plane of the dials.The center angle of the circle corresponding to the spacing of the two adjacent scribes is called the grid value of the dials,also known as the Z small grid value of the dials.Generally,the accuracy is determined by the size of the grid value,which is divided into:

　　DJ6 scale value is 1°DJ2 scale value is 20'DJ1(T3)scale value is 4'

　　From high accuracy to low accuracy:DJ0.7,DJ1,DJ2,DJ6,DJ30,etc.(D,J are the initial letters of the earth and theodolite respectively)

　　Theodolite is a precision measuring instrument used to measure angles in measurement tasks,which can be used for angle measurement,engineering lofting,and rough distance measurement.The entire instrument consists of two parts:the instrument and the tripod.