Patent ID: 10031230

Abstract:
In a method for optically measuring the properties of at least one measurement path (I1, I2) between a transmitter (H) and a receiver (D), the receiver (D) receives an optical signal from a compensation transmitter (K) in addition to an optical signal from the transmitter (H). The signal of the transmitter (H) is reflected by an object (O) or is transmitted to the receiver (D) by means of said object in a different manner. The output signal (SO) of the receiver (D) is fed to a controller (CT), which changes the transmitter feed signal (S5) and/or compensation feed signal (S3) in accordance with a control algorithm. In the process, the controller (CT) determines two signals or values, which represent control parameters (S4a, S4φ) for magnitude and phase or magnitude and delay. In a stage downstream of the controller (CT), the presence and/or the distance (r) of an object (O) is determined from said two control parameters (S4a, S4φ) in dependence on at least one of said two parameters, either from both parameters or from one of the two parameters.