subtense การใช้

A theodolite is used to measure the angle between indicators on the two ends of the subtense bar.
A subtense bar is a fixed base ( usually 2 meters long ) used in conjunction with a theodolite in the calculation of horizontal distance.
Since the ray cones approaching the detector surface have the same angle of incidence and angular subtense everywhere in the image plane, the image is evenly illuminated.
The distance from the telescope to the subtense bar is the height of an isosceles triangle formed with the theodolite at the upper vertex and the subtense bar length at its base, determined by trigonometry.
The distance from the telescope to the subtense bar is the height of an isosceles triangle formed with the theodolite at the upper vertex and the subtense bar length at its base, determined by trigonometry.