Laser sensor system based on self-mixing interference

1. A sensor module for measuring a distance to a target and/or a velocity of the target, the sensor module comprising:

at least one laser source for emitting laser light,

at least one detector being configured to detect modulated laser light and

at least one control element the control element being configured to vary a focus point of the laser, such that the distance to the target and/or the velocity of the target is measurable at different focus points;

wherein the sensor module further comprises at least two laser sources and at least two detectors and the laser sources are configured to emit laser light in essentially the same direction; and,

wherein the control element is configured to vary the focus point of the laser light emitted by said at least two laser sources differently.

2. A sensor module according to claim 1 , wherein the detector is configured to detect a modulation of resonating laser light in the laser source, the modulation of the laser light in the laser source being induced by reflected laser light reentering the laser source.

3. A sensor module according to claim 1 , whereby the control element comprises an optical element and the optical element being placed between the target and the laser source.

4. A sensor module according to claim 1 , wherein the sensor module comprises an array of laser sources and detectors and the control element for varying the focal point is a passive optical element.

5. A sensor module according to claim 4 , wherein the passive optical element is a lens or a mirror or an optical attenuator.

6. A sensor module according to claim 1 , wherein the range of detection of a first detector overlaps with the range of detection of at least one second detector.

7. A sensor module according to claim 6 , the sensor module further comprising an analyzer, the analyzer being arranged to verify a first measurement signal resulting from the detection of modulated laser light detected by the first detector by comparing the first measurement signal with at least a second measurement signal resulting from the detection of modulated laser light detected by the second detector.

8. A sensor module according to claim 1 , the sensor module further comprising a computing unit and an interface, the computing unit being arranged to determine a distance and/or a velocity data of the target based on measurement signals resulting from the detection of modulated laser light detected at least one detector and the interface being arranged to communicate the distance and/or velocity data of the target for further processing.

9. A sensor module according to claim 1 , wherein the control element is further configured to vary the intensity of the laser light.

10. A sensor module according to claim 1 , wherein the control element is further configured to vary the intensity of the laser light of the laser light emitted by at least two laser sources differently.

11. A method for measuring a distance to a target and/or a velocity of the target, the method comprising the steps of:

emitting laser light by means of at least two laser sources;

varying a focus point of the laser light and/or intensity of the laser light such that the distance to the target and/or the velocity of the target can be measured at different focus points; and,

detecting modulated laser light by means of at least two detectors;

wherein the laser light of said at least two laser sources is emitted essentially the same direction; and,

wherein the focus point of the laser light emitted by said at least two laser sources is varied differently.