Modern Surveying Instruments and Techniques
Modern surveying instruments make extensive use of infrared beams, laser beams,as well as computers. Using these instruments, it is possible to carry out fairly accurate surveying efficiently at all times, eliminating human error.
Electromagnetic Distance Measurement (EDM) Instruments
EDM instruments rapidly and automatically measure both horizontal and vertical distances. The readings can be displayed on built–in computer screens. Examples of such instruments are the geodimeter and the tellurimeter, which have been used in the past for electronic distance measurement of up to 80 km during day or night.Modern EDM instruments are much more advance and versatile.
Use of Computers
The results of the field survey are recorded in the form of angles and distances in the normal field book or electronic notebook. Using computers, it is possible to do all calculations as well as plot accurately. Thus, output from the EDM can be fed into the computer, which in turn can plot plans and sections.
Use of Laser in Surveying
Laser is an acronym for light amplification by stimulated emission of radiation. Its property of low diversion is used for alignment purposes. The invisible line of sight in ordinary survey instruments is replaced by the bright red beam of the Laser. This beam is intercepted by the target composed of light-sensitive cells connected to the display panel. Its most important aspect is that the beam is in a perfect straight line. Distances up to 70 km can be measured using laser. For short distances infrared beams are used.