3D IMAGE DETECTION AND RELATED 3D IMAGING SENSORS
A method of determining 3D information of a target includes emitting a light pulse and detecting a first incident photon by a detector element. The time of incidence of the detection of the first incident photon is determined and at the incidence time, a time window is opened with a predetermined duration. All the photons detected in the window are associated with the time of incidence detection of the first incident photon. The cycle is repeated and further first incident photons open another time window so that to each of the individual detector elements that detect further incident photons in the time windows, other incidence times are associated. The time difference between the received photons and the emitted pulse is determined and new cycles of detecting first incident photons and the opening of a new time window are repeated and 3D information of the target is provided.
1 . A method of determining 3D information of a target, the 3D information comprising the distance of multiple points of said target, the method comprising the steps of:
A. providing a 3D imaging sensor comprising a sender device comprising a pulsed light source, and a receiver device comprising a detector comprising a plurality of detector elements;
B. activating said sender device and emitting, at a start time, a light pulse;
C. detecting a first incident photon by one of said detector elements;
D. extracting the time of incidence of said first incident photon;
E. opening, at said time of incidence, a time window having a predetermined duration;
F. detecting, during said time window, further incident photons by said detector and identifying the individual detector elements that have detected said further incident photons;
G. associating, during said time window, to each of said individual detector elements that have detected said further incident photons, said time of incidence, and closing said time window
H. extracting the time interval Ti defined by T 1 −T 0 .
I. Repeating steps C to H by detecting at each cycle a new first incident photon.
J. Repeating the steps B to I.
2 . The method according to claim 1 , further comprising a step K of providing a 3D image of said target by using the information, provided during said time window, of said time of incidence associated to each of said individual detector elements.
3 . The method according to claim 1 , wherein the detector elements are single photon detection elements.
4 . The method according to claim 3 , wherein the single photon detection elements are single photon avalanche diodes.
5 . The method according to claim 1 , further comprising a step of activating a predetermined number N of detector elements of said detector.
6 . The method according to claim 5 , wherein said time window is applied only to all of said predetermined number N of detector elements.
7 . The method according to claim 1 , comprising a step to define the maximal number of incident photons that may be registered during said duration.
8 . The method according to claim 7 , wherein the definition of said maximal number of incident photons may be changed during any one of steps A-J.
9 . The method according to claim 7 , wherein the definition of said maximal number of incident photons is depending on internal or external conditions.
10 . The method according to claim 1 , wherein said predetermined duration may be changed during any one of steps A-J.
11 . The method according to claim 10 , wherein the change of duration is depending on internal or external conditions.
12 . The method according to claim 11 , wherein said internal conditions are variables of the 3D imager chosen among: the power consumption, the activity of the detector matrix, duration of the laser impulse, the temperature of the imager device, or a combination thereof.
13 . The method according to claim 11 , wherein said external conditions are variables of the environment of the 3D imager chosen among: the background light, the ambient temperature, the average luminosity, the local time, the detection of day and night, the absolute or relative speed of the target, the spectral characteristics of the target or a combination thereof.
14 . The method according to claim 1 , wherein said time window is generated by a pulse shaper block.
15 . The method according to claim 1 , wherein said time window is defined as an electrical gating signal.
16 . A 3D imaging sensor for determining a range to a target comprising:
a sender device, comprising a light source configured for emitting, at a start time, a light pulse;
a receiver device, comprising a detector comprising a plurality of detector elements for detecting incident photons,
the receiver device being configured for detecting a first incident photon and for extracting the time of incidence of the detection of said first incident photon,
the receiver device being configured for. opening, at said time of incidence, a time window having a predetermined duration of time,
the receiver device being configured for detecting, during said time window, further incident photons by said plurality of detector elements and for identifying the individual detector elements that have detected said further incident photons,
the receiver device being configured for associating, during said time window, to each of said individual detector elements said time of incidence,
the receiver device being configured for extracting the time interval Ti being equal to T 1 −T 0 , the receiver device being configured for repeating the opening and closing of successive time windows at the incidence of first incident photons.
17 . The 3D imaging sensor according to claim 16 , comprising a time-to-digital converter, a time window generator, a memory.
18 . The 3D imaging sensor according to claim 17 , wherein the time-to-digital converter comprises a clock source as a time reference for the time conversion, and a system of latches.
19 . The 3D imaging sensor according to claim 16 , wherein said time window generator comprises a pulse shaper block.