Editing Laser rangefinder (section)

==Technologies==
[[File:Su-27UB cockpit.jpg|thumb|An OLS-27 [[IRST]] with laser rangefinder on the [[Sukhoi Su-27]]]]
'''[[Time of flight]]''' - this measures the time taken for a light pulse to travel to the target and back. With the speed of light known, and an accurate measurement of the time taken, the distance can be calculated. Many pulses are fired sequentially and the average response is most commonly used. This technique requires very accurate sub-[[nanosecond]] timing circuitry.

'''Multiple frequency phase-shift''' - this measures the phase shift of multiple frequencies on reflection then solves some [[simultaneous equations]] to give a final measure.

'''[[Interferometry]]''' - the most accurate and most useful technique for measuring changes in distance rather than absolute distances.

'''Light attenuation by atmospheric absorption''' - The method measures the attenuation of a laser beam caused by the absorption from an [[Atmospheric chemistry|atmospheric compound]] ([[Water vapor |H<sub>2</sub>O]], [[Carbon dioxide |CO<sub>2</sub>]], [[Methane |CH<sub>4</sub>]], [[Allotropes of oxygen |O<sub>2</sub>]] etc.) to calculate the distance to an object. The light atmospheric absorption attenuation method requires unmodulated incoherent light sources and low-frequency electronics that reduce the complexity of the devices. Due to this, low-cost light sources can be used for range-finding. However, the application of the method is limited to atmospheric measurements or planetary exploration.<ref>{{Cite journal |last1=Siozos |first1=Panagiotis |last2=Psyllakis |first2=Giannis |last3=Velegrakis |first3=Michalis |date=2022-11-02 |title=A continuous‐wave, lidar sensor based on water vapour absorption lines at 1.52 μm |url=https://www.tandfonline.com/doi/full/10.1080/2150704X.2022.2127130 |journal=Remote Sensing Letters |language=en |volume=13 |issue=11 |pages=1164–1172 |doi=10.1080/2150704X.2022.2127130 |s2cid=252826003 |issn=2150-704X|url-access=subscription }}</ref>