Method and device for carrying out frequency synthesis in a distance measuring device

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG.
1, one example of a distance measuring device is shown, which is equipped with a device according to the invention for carrying out frequency synthesis.
The distance measuring device has a laser source 1, which preferably emits visible laser radiation.
The emitted laser radiation, collimated by a collimating optical system 2, is split by a beam splitter 11 into a measurement beam S and as a reference beam R.
As an example, a partly transparent mirror can be used as the beam splitter 11.
The measurement beam S reaches a measurement object whose distance from the distance measuring device is to be measured.
The radiation L remitted or scattered by the measurement object is collected by a receiving optical system 3 and carried to a measuring receiver 4.
A pin photodiode can be used, for instance, as the measuring receiver 4.
The reference beam R is deflected by a deflecting mirror 12 and collected by an optical system 13 and carried to a reference receiver 14.
The reference receiver 14 is advantageously structurally identical to the receiver 4 for the measurement beam L.
The distance traveled by the reference beam R from the beam splitter 11 to the reference receiver 14 forms the reference distance required to determine the phase difference.
The optical radiation emitted by the laser source 1 has a high-frequency modulation frequency M impressed on it that is generated by a frequency synthesizer 9, which is triggered by a reference quartz oscillator 10.
By means of the high-frequency modulation frequency M, high-frequency electrical measurement signals HF.
sub.
L, HF.
sub.
R, respectively, are generated at the receiver 4 and at the reference receiver 14, and they are present at the input of devices, embodied according to the invention, for signal detection; in FIG.
1, these devices are identified by reference numerals 5 and 15, respectively.
The frequency synthesizer 9 also generates a control frequency F of a similarly high frequency, which is delivered via a connecting line to the two devices 5, 15 for signal detection and which indicates the cadence for both devices 5, 15