Optical distance measuring method and corresponding optical distance measurement device
In order to derive a distance to a target object, in the detection of lower and upper dynamic ranges different detection methods are used simultaneously for the same light signal in an opto-electric distance measuring method having at least one emission of at least one light signal onto a target object and one detection of the light signal scattered back by the target object, wherein the upper dynamic range is recorded by means of a threshold value method and the lower dynamic range is recorded by means of signal scanning for the identification and temporal positioning of the back-scattered light signal.
1. A distance measuring method comprising:
emitting at least one light signal to a target object;
detecting the light signal scattered back by the target object; and
deriving a distance to the target object, wherein:
detection methods differing for a lower and an upper dynamic range are used in parallel simultaneously during detection for the same light signal, the lower dynamic range being below the saturation limit of a sampling unit for signal sampling and the upper dynamic range being above the saturation limit;
the upper dynamic range is determined by a threshold value method; and
the lower dynamic range is determined by signal sampling for identifying the back-scattered light signal and determining the position thereof as a function of time.
2. A distance measuring method according to claim 1 , wherein the signal sampling is effected cumulatively for a plurality of light signals.
3. A distance measuring method according to claim 1 , wherein the light signal is emitted in pulsed form and the derivation is effected by a pulse transit time measuring method.
4. A distance measuring method according to claim 3 , wherein, during emission, a sequence of light pulses is emitted and the derivation of at least one distance is effected for each of the light pulses.
5. A distance measuring method according to claim 1 , wherein the light signal is emitted with continuous modulation and the derivation is effected by a phase measuring method.
6. A distance measuring method according to claim 1 , wherein the amplitude or energy of the back-scattered light signal is determined for calculating the dependence of the switching point of the threshold value method on the amplitude or energy of the back-scattered light signal.
7. An electro-optical distance measuring device comprising:
a beam source for emission of at least one light signal to a target object;
a receiver for detection of the light signal scattered back by the target object;
a threshold value-dependent detection unit;
a sampling unit for sampling the back-scattered light signal; and
a control and evaluation component for deriving a distance to the target object, wherein the receiver has a lower and an upper dynamic range, the lower dynamic range being below the saturation limit of the sampling unit and the upper dynamic range being above the saturation limit and the threshold value-dependent detection unit covering the upper dynamic range and the sampling unit covering the lower dynamic range.
8. A distance measuring device according to claim 7 , wherein an electrical or optical attenuator upcircuit of the receiver is controlled in such a way that the receiving power is kept constant.
9. A distance measuring device according to claim 7 , wherein the signal source is controlled in such a way that the receiving power is kept constant.
10. A distance measuring device according to claim 7 , further comprising a receiving optical system and/or amplifier stage common to the threshold value-dependent detection unit and the sampling unit.
11. A distance measuring device according to claim 7 , wherein the radiation source is configured to emit a continuously modulated light signal and the control and evaluation component includes a phase measuring device.
12. A distance measuring device according to claim 7 , wherein the radiation source is configured to emit a pulsed light signal and the control and evaluation component includes a transit time measuring device.