Editing Laser rangefinder (section)

==Calculation==
[[File:20200501 Time of flight.svg|thumb|upright=1.5| Time-of-flight principles applied to laser range-finding.]]
The distance between point A and B is given by
:<math>D=\frac{ct}{2}</math>
where <var>c</var> is the speed of light and <var>t</var> is the amount of time for the round-trip between A and B.

:<math>t=\frac{\phi}{\omega}</math>
where <var>φ</var> is the phase delay made by the light traveling and <var>ω</var> is the angular frequency of optical wave.

Then substituting the values in the equation,

:<math>D=\frac{1}{2} ct = \frac{1}{2} \frac{c \phi}{\omega} = \frac{c}{4 \pi f}  (N \pi + \Delta \phi) = \frac{\lambda}{4}(N+ \Delta N)</math>

In this equation, <var>λ</var> is the wavelength {{sfrac|''c''|''f''}}; <var>Δφ</var> is the part of the phase delay that does not fulfill {{pi}} (that is, <var>φ</var> modulo {{pi}}); <var>N</var> is the integer number of wave half-cycles of the round-trip and Δ<var>N</var> the remaining fractional part.