Infrared Wave Instruments
These instrument measure distances by using amplitude modulated infrared waves. At the end of line, prisms mounted on target are used to reflect the waves. These instruments are light and economical and can be mounted on theodolites for angular measurements. The range of such an instrument will be 3km and the accuracy achieved is ± 10 mm.

Light Wave Instruments
These are the instruments which measures distances based on propagation of modulated light waves. The accuracy of such an instrument waries from 0.5 to 5mm/km distance and has a range of nearly 3km.

Microwave Instruments
These instruments make use of high frequency radio waves (micro-waves). These instruments were invented as early as 1950 in South Africa by Dr. T.L. Wadley. The range of these instruments is up to 100km and can be used both during day and night.