Method and apparatus for mapping and ranging based on coherent-time comparison

A system for measuring a distance to a target object comprising at least one light source configured to provide an illumination beam of a selected wavelength range and a defined coherence length, an optical arrangement, and a detection arrangement comprising at least one detector unit,

• said optical arrangement comprises optical elements forming at least first and second interferometers, each of said first and second interferometers is formed of a reference path and an interrogating path, said interrogating path comprises optical arrangement adapted to direct interrogating beam portions of said illumination beam toward a target object and collect return beam portions reflected from said target object, wherein the interrogating beam portions of the interrogating paths of the first and second interferometers spatially overlap at least at a point of impinging on the target object such that the first and second detected signals correspond to interference signals formed using light reflected from a common location on the target object;
• said reference path and interrogating path generate an interference signal on at least one detector of the detection arrangement, thereby generating detection data comprising at least first and second detected signals indicative of interference signal of said first and second interferometers;
• wherein said first and second interferometers are configured with respective first and second different coherence factors being associated with at least one of optical path of reference paths of the first and second interferometers, and coherence length of light passing in said first and second interferometers;
• wherein said at least one light source comprises at least one laser unit configured to emit the illumination beam having the defined coherence length and a fixed instantaneous frequency, wherein the illumination beam being provided as a continuous-wave (CW) or a pulsed beam;
• and wherein the system is configured to determine a coherence ratio term being a ratio between said at least first and second detected signals and uses said coherence ratio term to determine a distance to said target object.