Method and device for optoelectronic distance measurement
First Claim
1. A method for optoelectronic distance measurement, wherein an intensity-modulated main light beam emitted by a main light emitter is directed to a measurement object at a distance, wherein the distance (D0) of a measurement object from an observation point is to be measured, and a light scattered at the observation point reaches a main photoreceiver via reception optics, and a branched part of the main light beam is simultaneously directed to a reference photoreceiver via a first known reference distance (D1), an intensity-modulated reference light beam emitted by a reference light emitter reaches the reference photoreceiver via a second known reference distance (D2), and a part of the reference light beam reaches the main photoreceiver via a third reference distance (D3), and wherein the signals delivered by the main photoreceiver and the reference photoreceiver are subjected to a comparative signal evaluation for obtaining a corrected measurement signal, wherein the light intensities of the main emitter and the reference emitter are simultaneously intensity-modulated at different frequencies, wherein the signal mixtures supplied by the main receiver and the reference receiver, each of the signal mixtures contains a signal component with the intensity modulation frequency of the main emitter and a signal component with the intensity modulation frequency of the reference receiver, are converted to an intermediate frequency range containing two frequency components, wherein one frequency component is formed by the signal of the reference emitter and the other frequency component is formed by the signal of the main emitter, and the separation of the phase information contained in the two simultaneously occurring intermediate frequency signals is based on the different frequencies in the intermediate frequency range and the different modulation frequencies for the intensity modulation of the main light beam and reference light beam for purposes of comparative signal evaluation.
1 Assignment
0 Petitions
Accused Products
Abstract
The invention is directed to a method for optoelectronic distance measurement and a measurement device based on this method, in which two light emitters, particularly laser emitters and two photodiode receivers are used for calibration. Part of the modulated output of the main emitter reaches the measurement object and then arrives at the main photoreceiver in the form of scattered light and another part of the output of the main emitter travels directly to a reference photoreceiver, while a part of the modulated output of the reference light emitter is guided directly to the main photoreceiver and another part is guided directly to the reference photoreceiver. According to the invention, the light intensities of the main emitter and the reference emitter are simultaneously modulated with different modulation frequencies (f1, f2), and a signal mixture is formed in the main receiver as well as in the reference receiver, which signal mixture contains a signal with the intensity modulation frequency (f1) of the main emitter and a signal with the intensity modulation frequency (f2) of the reference emitter. The phases of the two signals of the signal mixture are measured simultaneously and the separation of the two phases is carried out by the different frequencies in a subordinate intermediate frequency range and by the different intensity modulation frequencies. At least two sequential measurement processes are preferably carried out, wherein the intensity modulation frequencies of the reference emitter and main emitter are exchanged in the second measurement process. Phase errors depending upon temperature, aging and reception power can be entirely eliminated by the invention in electro-optic distance measuring devices.
-
Citations
30 Claims
- 1. A method for optoelectronic distance measurement, wherein an intensity-modulated main light beam emitted by a main light emitter is directed to a measurement object at a distance, wherein the distance (D0) of a measurement object from an observation point is to be measured, and a light scattered at the observation point reaches a main photoreceiver via reception optics, and a branched part of the main light beam is simultaneously directed to a reference photoreceiver via a first known reference distance (D1), an intensity-modulated reference light beam emitted by a reference light emitter reaches the reference photoreceiver via a second known reference distance (D2), and a part of the reference light beam reaches the main photoreceiver via a third reference distance (D3), and wherein the signals delivered by the main photoreceiver and the reference photoreceiver are subjected to a comparative signal evaluation for obtaining a corrected measurement signal, wherein the light intensities of the main emitter and the reference emitter are simultaneously intensity-modulated at different frequencies, wherein the signal mixtures supplied by the main receiver and the reference receiver, each of the signal mixtures contains a signal component with the intensity modulation frequency of the main emitter and a signal component with the intensity modulation frequency of the reference receiver, are converted to an intermediate frequency range containing two frequency components, wherein one frequency component is formed by the signal of the reference emitter and the other frequency component is formed by the signal of the main emitter, and the separation of the phase information contained in the two simultaneously occurring intermediate frequency signals is based on the different frequencies in the intermediate frequency range and the different modulation frequencies for the intensity modulation of the main light beam and reference light beam for purposes of comparative signal evaluation.
- 14. A device for optoelectronic distance measurement with two light transmitters each having a light beam that is intensity-modulated, wherein the light beam of the first light transmitter being a main emitter, is directable to a measurement object at a distance, wherein the distance (D0) of the measurement object from an observation point is to be measured, and a separate light component reaches one of two photoreceivers, via a first reference distance (D1), and wherein the light beam of the second light transmitter, reaches one of the reference receivers via a second reference distance (D2), and a beam component separated from the light beam of the second light transmitter reaches a second photoreceiver being a main receiver, via a third reference distance (D3), the second photoreceiver being acted upon in addition by a component of the light beam of the main emitter backscattered from the measurement object, with two signal mixers each being associated with the reference receiver and the main receiver and transforming the receiver signal mixtures into an intermediate frequency range, and an evaluating device for determining the measurement distance (D0) from the output signals of the two mixers, wherein a device by which the light beams emitted by the main emitter and reference emitter can be simultaneously intensity-modulated with different frequencies (f1, f2).
Specification