LASER DISTANCE MEASURING MODULE WITH INL ERROR COMPENSATION

Description

[0001] The present invention relates to a distance measuring method and an electronic laser distance measuring module, in particular for use in a distance measuring device, e.g. in a laser tracker, tachymeter, laser scanner, or profiler, for fast signal acquisition with an analog-digital converter, wherein a compensation of the integral nonlinearity of the analog-digital converter takes place.

[0002] Various principles and methods are known in the field of electronic or electro-optical distance measurement. One approach involves emitting pulsed electromagnetic radiation, such as laser light, at a target to be measured and subsequently receiving an echo from this target as a backscattering object. The distance to the target to be measured can be determined, for example, based on the time of flight, the shape, and / or the phase of the pulse. Such laser distance meters have now become standard solutions in many fields.

[0003] To detect the backscattered pulse, two different approaches or a combination of them are usually used.

[0004] In the so-called threshold method, a light pulse is detected when the intensity of the radiation incident on a detector of the distance measuring device used exceeds a certain threshold. This threshold prevents background noise and interfering signals from being falsely detected as the useful signal, i.e., as backscattered light from the emitted pulse.

[0005] The other approach is based on sampling the backscattered pulse. This approach is typically used for weak backscattered signals (e.g., pulse signals), such as those caused by larger measurement distances, or generally to increase measurement accuracy. An emitted signal is detected by sampling the radiation detected by a detector, identifying a signal within the sampled area, and finally determining the signal's position in time. By using a large number of samples and / or summing the received signal synchronously with the emission rate, a useful signal can be identified even under unfavorable conditions, thus enabling the detection of larger distances or noisy or disruptive background scenarios.

[0006] Nowadays, the entire waveform of the analog signal of the radiation detected by a detector is often sampled using the waveform digitizing (WFD) method. After identifying the coding of the corresponding transmitted signal (ASK, FSK, PSK, etc.) of a received signal, a signal propagation time ("pulse propagation time") is determined very precisely from a defined point in the sampled, digitized, and reconstructed signal, for example, the inflection points, the curve maxima, or integrally using an optimum filter known from time interpolation.

[0007] Alternatively or in addition to determining the pulse transit time, (fast) sampling is often also carried out with regard to pulses or pulse sequences encoded or modulated in amplitude, phase, polarization, wavelength and / or frequency.

[0008] In the approach of very precise temporal sampling or sampling of the backscattered signal, the electrical signal generated by the detector is converted into a digital signal sequence using an analog-to-digital converter (ADC). This digital signal is then usually further processed in real time. In a first step, the signal, often modulated as a pulse, is detected by special digital filters, and finally, its position within the signal sequence is determined. By using a large number of sampled pulse sequences, a useful signal can be identified even under unfavorable conditions, so that even greater distances or noisy or disruptive background scenarios can be handled.

[0009] One of the simplest modulation types is the identification of individual pulses or pulse sequences using distance coding, as described, for example, in EP 1 832 897 B1. This is used, for example, for the purpose of re-identification. This recognition is necessary when ambiguity arises, which can be caused by different situations during pulse propagation time measurement, for example, when there is more than one pulse or pulse group between the surveying device and the target object.

[0010] In fast analog-to-digital converters (ADCs), the high sampling rate in combination with a high resolution of the signal amplitude (e.g. 1GS / s, 14bit) is achieved, for example, by generating several ADC conversion stages, for example by: a temporal interleave of several slow ADC cores, a step-by-step quantization of the sampled signal amplitudes ("pipeline"), or a combined multi-stage quantization of the signal samples from several ADC cores.

[0011] Despite careful internal corrections, these architectures exhibit architecture-specific errors. These errors vary over time and temperature.

[0012] In interleaved ADC, the typical errors have the following effects: Skew (timing error between the sample times of the different ADC cores or ADCs) Gain (different amplification factor between the internal ADC core components. The signal is usually amplified and / or buffered in the ADC) Offset (different DC levels of the internal outputs of the ADC cores)

[0013] Especially in pipelined ADCs, typical errors usually manifest as differential nonlinearity (DNL) and integral nonlinearity (INL). DNL and INL are errors in the conversion of analog signal values to digital (integer) values, caused, for example, by the gradual quantization of a pipelined ADC with increasingly finer steps / increasing resolution.

[0014] The INL error is essentially the subtotal of all contributions from the DNL errors below the signal level to be converted and can reach several LSBs ("Least Significant Bits"). Therefore, the INL error in particular has a serious impact on the digitized signal shape accuracy even with moderate fluctuations in the signal values.

[0015] The digitized signal waveform no longer corresponds to the original analog signal waveform. These DNL and INL errors can be partially minimized, but not eliminated, through internal corrections in the ADC component. External calibration, which can be achieved by measuring and recording the residual error, is time-dependent and, for example, highly temperature-dependent.

[0016] In distance measurements, the INL error over distance results in a periodic distance error in the distance of the scanning / sampling grid. Furthermore, an INL error generates a distance error that depends on the received signal value. The edges of a digital signal pulse are distorted by the quantization errors in the deflection, which can shift the position of the signal pulse relative to the time axis. Errors in the measured distance can also occur in distance measurement systems with start and stop pulses or start and stop signal sequences. For example, this is the case if the start pulse has an amplitude in the middle of the control range, whereas the stop pulse has an amplitude in the lower amplitude range. Due to INL-related shape distortion, both pulses are deformed differently and the absolute distance is distorted. Lukasz Malkiewicz "Improvement of intelligent cyclic ADC resolution by randomization of DAC INL errors." Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments (2012): 84540Z. describes the improvement of the INL error in ADCs by an additive random input signal.

[0017] It is therefore an object of the invention to provide an improved distance measurement with simultaneously high measurement accuracy and high distance resolution.

[0018] A specific object of the invention is to provide an improved method and an improved system for signal digitization.

[0019] Another specific object of the invention is to provide improved compensation of the INL error during signal digitization.

[0020] These objects are solved by the independent claims. Features that further develop the invention in an alternative or advantageous manner can be found in the dependent patent claims.

[0021] The invention relates to a distance measuring method, in particular for a laser distance measuring device, specifically designed as a laser tracker, tachymeter, laser scanner, or profiler, for determining a distance to a target object by emitting pulsed transmission signals as a transmission signal series; receiving at least parts of the transmission signals of the transmission signal series reflected at the target object as reception signals of a reception signal series; superimposing a defined, varying bias signal on the reception signal series, thereby generating an ADC input signal series, wherein the value of the bias signal is varied over time such that reception signals of the reception signal series are superimposed with different offset values within a defined value range, in particular wherein the bias signal is mean-free over the period occupied by the reception signal series;digitizing the received signals of the ADC input signal series into digital signals of a digital signal series by means of an analog-to-digital converter, hereinafter referred to as ADC, in particular of the interleave ADC or pipeline ADC type; and processing the digital signal series, namely summing or averaging the digital signals across the digital signal series in order to derive the distance to the target object therefrom; wherein the determination of the distance is based on the pulse transit time method.

[0022] The linear part of the global trend of an error due to an integral nonlinearity of the ADC, hereinafter referred to as INL error, as a function of the signal value of an ADC input signal (INL trend, e.g. typically an "S-shape", see Fig. 4) essentially only generates a signal gain error and has no impact on the distance measurement accuracy. The INL error, on the other hand, can vary significantly locally with the ADC sampling rate, resulting in a distance measurement error that is, for example, singly periodic or multi-periodic with the ADC sampling rate.

[0023] By varying the value of the bias signal, the actual ADC measurement signal and thus individual received signals are shifted over a wide range of values, thereby covering various (local) error zones of the INL error. By processing multiple received signals (e.g., individual pulse signals, "single shots"), for example, by averaging or summing, an average is automatically generated across different INL error contributions, thus minimizing the (local) INL error in the processed digitized signal.

[0024] In the special case where the bias signal is mean-free over the period occupied by the received signal series, the local INL error is minimized because both the start pulse and the stop pulse are detected and averaged over significant local INL-related shape distortions.

[0025] The error of the final measured absolute distance is thus minimized. In the case of a general, non-zero-mean, variable bias signal, however, an essentially constant offset along the amplitude direction of an INL error curve (see Fig. 5 ) is introduced, which can be taken into account in the calibration of the global INL error.

[0026] In particular, in a special embodiment, the different offset values are taken into account when processing the digital signal series in order to compensate for a mean integral nonlinearity of the ADC as a function of a signal value of an ADC input signal.

[0027] In particular, the bias signal is designed as a signal with a low-frequency oscillation component (for example with a frequency < 1 MHz), in particular a sine signal, a sawtooth signal, a staircase signal, a triangular signal, or a trapezoidal signal.

[0028] In a further embodiment, the bias signal is generated by at least one of the following measures: adding different discrete DC values to an ADC input signal of an ADC input signal series generated by the received signal series at different times of the ADC input signal series, in particular set by a digital-to-analog converter, hereinafter referred to as DAC; periodically shifting the offset level of the common-mode voltage of the ADC; and a noise generator for generating a variable additional signal to the ADC input signal series, in particular by utilizing the thermal noise of resistors, diodes or the like or by superimposing a pseudo-random sequence generated by feedback shift registers.

[0029] The mean (local) INL error can, for example, vary as a function of a mean signal value across different value ranges, e.g., in the sense that the (local) INL error is larger for a region with a higher mean signal value than for a region with a lower mean signal value. Furthermore, the minimization of the local INL error, and thus the achieved distance measurement accuracy, depends crucially on the value range over which the actual measurement signal is varied (and thus averaged).

[0030] A specific embodiment relates to an adjustment of the value range of the bias signal, in particular with an FPGA or a microprocessor, based on a defined measurement accuracy for determining the distance and / or a measured value of a received signal. REPLACEMENT PAGE - FAIR COPY

[0031] The invention further relates to an electronic laser distance measuring module, in particular for use in a distance measuring device, specifically designed as a laser tracker, tachymeter, laser scanner, or profiler, for determining a distance to a target object, comprising a transmission channel with a transmission unit for generating optical transmission signals of a transmission signal series by means of pulsed laser measuring radiation; a reception channel with a reception unit for receiving at least parts of the transmission signals of the transmission signal series reflected at the target object as reception signals of a reception signal series;wherein the laser distance measuring module is designed such that a defined varying bias signal is generated, and the received signal series is superimposed with the bias signal, whereby an ADC input signal series is generated, wherein the value of the bias signal is varied over time such that received signals of the received signal series are superimposed with different offset values within a defined value range, in particular wherein the bias signal is mean-free over the period of time required by the received signal series, a receiving circuit for digitizing the ADC input signal series into digital signals of a digital signal series with an analog-to-digital converter, hereinafter referred to as ADC, in particular of the interleave ADC or pipeline ADC type;and a control and monitoring unit for determining the distance to the target object based on processing the digital signal series, namely summing or averaging the digital signals across the digital signal series; wherein the determination of the distance is based on the pulse transit time method.

[0032] According to the present invention, the laser distance measuring module is adapted such that a defined varying bias signal is generated and the received signal series is superimposed with the bias signal, wherein the value of the bias signal is varied over time such that received signals of the received signal series are superimposed with different offset values within a defined value range, in particular wherein the bias signal is mean-free over the period required by the received signal series.

[0033] In a special embodiment, the laser distance measuring module is designed such that the different offset values are taken into account when processing the digital signal series by the control and monitoring unit in order to compensate for a mean integral nonlinearity of the ADC as a function of a signal value of an ADC input signal.

[0034] In a further embodiment of the laser distance measuring module according to the invention, the bias signal is designed as a signal with a low-frequency oscillation component (e.g. with an oscillation frequency < 1 MHz), in particular a sine signal, a sawtooth signal, a staircase signal, a triangular signal, or a trapezoidal signal.

[0035] The bias signal can be generated, for example, by at least one of the following measures: adding different discrete DC values to an ADC input signal of an ADC input signal series generated by the received signal series at different times of the ADC input signal series, in particular set by a digital-to-analog converter, hereinafter referred to as DAC; periodically shifting the offset level of the common-mode voltage of the ADC; and a noise generator for generating a variable additional signal to the ADC input signal series, in particular by utilizing the thermal noise of resistors, diodes or the like or by superimposing a pseudo-random sequence generated by feedback shift registers.

[0036] In an advantageous embodiment, the laser distance measuring module according to the invention is adapted such that the value range of the bias signal is set, in particular with an FPGA or a microprocessor, based on a defined measurement accuracy for determining the distance and / or a measured value of a received signal. REPLACEMENT PAGE - FAIR COPY

[0037] The distance measurement method and the laser distance measurement module according to the invention are described in more detail below, purely by way of example, using exemplary embodiments schematically illustrated in the drawings. Identical elements are identified by identical reference numerals in the figures. The described embodiments are generally not drawn to scale and are not to be understood as limiting.

[0038] Show in detail Fig. 1a,b: Schematic illustration of the pulse transit time method in an electro-optical distance measuring device according to the prior art; Fig. 2a,b: Principle representation of digitization by an analog-to-digital converter (ADC) with a linear relationship between the ADC input signal and the digitized output values (a) and with a differential nonlinearity (b); Fig. 3: Typical error curve for a differential nonlinearity of an ADC; Fig. 4: Typical error curve for an integral nonlinearity of a fast ADC; Fig. 5: Illustration of compensation of the INL error by superimposing a varying bias signal on the measurement signal generated by the detected received signals; Fig. 6: Illustration of an averaging over several received signals, which were superimposed with a varying bias signal according to the invention to generate the ADC input signal; Fig.7: exemplary embodiment of a receiving channel of a laser distance measuring module according to the invention.

[0039] The Figures 1a and 1b illustrate the pulse transit time principle as used in typical state-of-the-art electro-optical distance measuring devices.

[0040] Figure 1a shows a schematic diagram of a prior art electro-optical distance meter 1 based on the pulse transit time principle. A transmitter 2 and a receiver 3 are arranged in the distance meter 1. The transmitter 2 emits a light pulse 4, which, after being reflected or backscattered by a target, e.g., a cooperative target object such as a retroreflector 5 or an uncooperative target object such as a natural surface, is detected again as a backscattered light pulse 4' by the receiver 3. Instead of light pulses, a continuously modulated transmission signal is often used.

[0041] As in Figure 1bAs explained schematically, the distance is determined from the transit time T f as the time difference between the start time of the transmission of a light pulse 4 and the reception time of the backscattered light pulse 4'. The reception time is determined by evaluating a feature of the signal pulse s(t), e.g. by exceeding a signal threshold or - as in the present invention - by sampling the signal pulse, wherein after identifying the coding of the associated transmission signal of a received signal, a pulse transit time is determined very precisely from a defined curve point of the sampled and digitized signal, for example the inflection points, the curve maxima, or integrally by means of an optimum filter known from time interpolation. Another method for determining a defined curve point includes, for example,also a conversion of the received signal into a bipolar signal and a subsequent determination of the zero crossing.

[0042] During the precise temporal sampling of the backscattered pulse, the electrical signal generated by the detector is converted into a digital signal sequence using an analog-to-digital converter (ADC), which is then usually further processed in real time. By using a variety of sampling sequences and / or summing the received signal synchronously with the emission rate, a useful signal can be identified even under unfavorable conditions, allowing even greater distances or noisy or disruptive background scenarios to be addressed.

[0043] In fast analog-to-digital converters (ADCs), the high sampling rate combined with high signal resolution is achieved, for example, by temporally interleaving several slow ADCs and / or by gradual quantization ("pipelining"). Despite careful internal corrections, this results in architectural errors that vary over time and, for example, temperature.

[0044] Especially in pipelined ADCs, typical errors usually manifest as differential nonlinearity (DNL) and integral nonlinearity (INL). DNL and INL are errors in the conversion of the analog signal value into digital (integer) values, caused, for example, by the gradual quantization in a pipelined ADC with increasingly finer steps / increasing resolution.

[0045] The Figures 2a and 2billustrate the effect of differential nonlinearity (DNL) during digitization by an analog-to-digital converter (ADC). Each figure shows a plot of the generated digital signal DS as a function of the voltage V of an analog ADC input signal.

[0046] Figure 2a illustrates the ideal case, where digitization occurs such that the difference between the threshold voltage and the next digital value is constant, i.e., a linear digitization is generated with a digitization step function 6a whose step width V LSB is constant. Two adjacent digital values, e.g., the digital values 001 and 010, thus correspond to two converted analog input voltages that are exactly one target voltage V LSB ("Least Significant Bit") apart.

[0047] In contrast, Figure 2bthe effect of a differential nonlinearity DNL, where adjacent digital values, for example, the digital values 001 and 010, correspond to analog input voltages whose voltage difference is smaller or larger than the target voltage V LSB. This results in a nonlinear digitization with a digitization step function 6b with different step widths.

[0048] The INL error is essentially the sum of all DNL errors summed up to the voltage value V of the input signal and can reach several LSBs. Therefore, the INL error in particular has a serious impact on the digitized signal shape accuracy even with moderate fluctuations in the signal value. In distance measurement, the INL error over distance, for example, results in a simple periodic distance error in the sampling grid spacing.

[0049] Figure 3shows a typical error curve 7 for a differential nonlinearity (DNL), for example, of a single ADC in an interleave ADC architecture or a quantization stage of a pipelined ADC. The DNL error curve 7 shows the deviation of neighboring digitized values from the ideal target value of one LSB ("Least Significant Bit") level as a function of the input voltage V.

[0050] Figure 4 shows a typical error curve 8 for an integral nonlinearity INL, for example, a fast interleave ADC architecture or a pipelined ADC. The INL error curve 8 shows the deviation of the digitized value from the ideal target value as a function of the ADC input voltage V, expressed in LSB units.

[0051] The global shape of the INL error curve 8 (typically S-shaped) is represented here for simplicity by a zigzag line 9 with three different gradients. If the sampled voltage values of a received signal remain within an INL range with a substantially linear gradient, this generates an amplitude-dependent signal amplification, which leads to a distortion of the pulse shape and reduces the distance measurement accuracy. If the sampled signal shape contains larger deviations from a mean, linear gradient range of the INL curve (e.g., the signal shape includes a "kink" in the zigzag line 9), further distortions of the signal shape occur, and the accuracy of a distance measurement exhibits cyclic errors relative to the sampling grid. The same considerations also apply to the start pulse.The minimum deflection of the varying bias signal should therefore be chosen to be sufficiently large so that, for example, the sample values assigned to the start and stop pulses each cover a linear gradient range of the INL curve on average.

[0052] A local curvature of the INL error curve 8 (the local deflections / deviations of the INL error curve 8 from the global curve 9) generates a distance measurement error that is, for example, at least simply periodic to the sampling raster. These local deflections of the INL curve significantly influence the distance measurement accuracy. The local curvature of the INL error curve and the resulting distance measurement error are corrected by the features of the present invention.

[0053] Figure 5 illustrates the correction of the INL error (the local curvature of the INL error curve 8, see Fig. 4) by superimposing the measurement signal generated by the detected reception signals with a varying bias signal 10.

[0054] The figure shows an ADC input signal series 11 (received signal series) generated according to the invention as a function of time t, consisting of a superposition of the actual measurement signal generated by several (pulsed) received signals 12 ("single shots") of a received signal series with the varying bias signal 10, here for example a low-frequency sine signal, wherein the superimposed bias signal 10 is mean-free over the period dT required by the ADC input signal series.

[0055] The bias signal 10 can in particular be a low-frequency oscillation signal, for example a sine, sawtooth, step, triangular, or trapezoidal signal, wherein the bias signal 10 can be generated, for example, by adding discrete DC values to the actually generated measurement signal, e.g. adjusted by a digital-to-analog converter (DAC).

[0056] Figure 6 illustrates an averaging over several received signals 12 ("single shots") of a received signal series, which is used to generate the ADC input signal series 11 (see Fig.5 ) according to the invention with a varying bias signal 10 (see Fig. 5 ) was superimposed.

[0057] By superimposing the bias signal 10, the actual measurement signal of a received signal 13 is shifted over a wide range of values during averaging, in a special embodiment without averaging, whereby different error zones of the INL error curve 8 (see Fig. 4). By averaging across multiple received signals, an average of different INL error contributions is obtained, which significantly reduces the influence of INL errors, particularly without deteriorating the signal-to-noise ratio (SNR). A particularly efficient elimination of the INL influence on the signal shape and thus on the distance measurement is achieved when the firing repetition rate is asynchronous to the sampling raster and asynchronous to the bias signal.

[0058] Figure 7shows an exemplary embodiment of a receiving channel 14 of a laser distance measuring module according to the invention with a receiving optics and a receiving unit 15 for receiving transmission signals reflected from a target object as received signals, system electronics 16 for processing the received signals into an analog electrical measurement signal, and a (fast) analog-to-digital converter (ADC) 17, for example with interleave architecture or pipeline architecture.

[0059] The bias signal 10 (see Fig. 5 ) is superimposed on the ADC input signal series 18, for example by adding discrete DC values to the actually generated measurement signal, e.g. set by a digital-to-analog converter (DAC) 19.

[0060] Due to the temporal variation of the INL error, for example due to temperature, due to different requirements for measurement accuracy and due to different reception strengths, the amplitude of the varying bias signal 10 can be varied if necessary, e.g. with an FPGA or microprocessor 20, which records and processes the ADC signal.

[0061] It is understood that these figures only schematically depict possible embodiments. The various approaches can also be combined with each other and with prior art methods.

Claims

1. Distance measuring method, in particular for a laser distance measuring apparatus, especially configured as a laser tracker, tachymeter, laser scanner, or profiler, for determining a distance to a target object comprising • emitting pulsed transmission signals, as a transmission signal series, • receiving at least portions of the transmission signals of the transmission signal series reflected at the target object as reception signals (12) of a reception signal series, • superimposing the reception signal series with a bias signal (10) that varies in a defined manner, whereby an ADC input signal is generated, wherein the value of the bias signal (10) is varied over time in such a way that reception signals (12) of the reception signal series are superimposed with different offset values within a defined value range in particular wherein the bias signal (10) is average-value-free over the time period occupied by the reception signal series • digitizing the ADC input signal into digital signals of a digital signal series by means of an analog-to-digital converter (17), referred to hereinafter as ADC, in particular of the interleave ADC or pipeline ADC type, and • processing the digital signal series, namely summing or averaging the digital signals over the digital signal series, in order to derive the distance to the target object therefrom, wherein the determination of the distance is based on the pulse time-of-flight method.

2. Distance measuring method according to claim 1, characterized in that the different offset values are taken into account during the processing of the digital signal series in order to compensate for an average integral nonlinearity (8) of the ADC as a function of a signal value of an ADC input signal (11).

3. Distance measuring method according to claim 1 or 2, characterized in that the bias signal (10) is configured as a signal having a low-frequency oscillation component, in particular a sinusoidal signal, a sawtooth signal, a staircase signal, a triangular signal, or a trapezoidal signal.

4. Distance measuring method according to any one of the preceding claims, characterized in that the bias signal (10) is generated by means of at least one of the following measures: • adding different discrete DC values to an actual measurement signal generated by the reception signal series at different instants of the actual measurement signal generated, in particular set by a digital-to-analog converter (19), referred to hereinafter as DAC, • periodically shifting the offset levels of the common-mode voltage of the ADC (17), and • a noise generator for generating a variable additional signal to the actual measurement signal generated.

5. Distance measuring method according to any one of the preceding claims, characterized in that the value range of the bias signal (10) is set, in particular by means of an FPGA or a microprocessor (20), on the basis of • a defined measurement accuracy for the determination of the distance, and / or • a measured signal value of a reception signal (12).

6. Electronic laser distance measuring module, in particular for use in a distance measuring apparatus, especially configured as a laser tracker, tachymeter, laser scanner, or profiler, for determining a distance to a target object comprising • a transmission channel having a transmitting unit for generating transmission signals of a transmission signal series by means of pulsed laser measurement radiation, • a reception channel (14) having a receiving unit (15) for receiving at least portions of the transmission signals of the transmission signal series reflected at the target object as reception signals (12) of a reception signal series, wherein the laser distance measuring module is configured in such a way that • a bias signal (10) that varies in a defined manner is generated, and • the reception signal series is superimposed with the bias signal (10), whereby an ADC input signal is generated, wherein the value of the bias signal (10) is varied over time in such a way that reception signals (12) of the reception signal series are superimposed with different offset values within a defined value range, in particular wherein the bias signal (10) is average-value-free over the time period occupied by the reception signal series wherein laser distance measuring module further comprises • a reception circuit for digitizing the ADC input signal into digital signals of a digital signal series with an analog-to-digital converter (17), referred to as ADC hereinafter, in particular of the interleave ADC or pipeline ADC type, and • a supervisory and control unit for determining the distance to the target object on the basis of a processing of the digital signal series, namely summing or averaging the digital signals over the digital signal series, wherein the determination of the distance is based on the pulse time-of-flight method.

7. Laser distance measuring module according to claim 6, characterized in that the different offset values are taken into account during the processing of the digital signal series by the supervisory and control unit in order to compensate for an average integral nonlinearity (8) of the ADC as a function of a signal value of an ADC input signal (11).

8. Laser distance measuring module according to claim 6 or 7, characterized in that the bias signal (10) is configured as a signal having a low-frequency oscillation component, in particular a sinusoidal signal, a sawtooth signal, a staircase signal, a triangular signal, or a trapezoidal signal.

9. Laser distance measuring module according to any one of claims 6 to 8, characterized in that the bias signal (10) is generated by means of at least one of the following measures: • adding different discrete DC values to an actual measurement signal generated by the reception signal series at different instants of the actual measurement signal generated, in particular set by a digital-to-analog converter (19), referred to hereinafter as DAC, • periodically shifting the offset levels of the common-mode voltage of the ADC (17), and • a noise generator for generating a variable additional signal to the actual measurement signal generated.

10. Laser distance measuring module according to any one of claims 6 to 9, characterized in that the value range of the bias signal (10) is set, in particular by means of an FPGA or a microprocessor (20), on the basis of • a defined measurement accuracy for the determination of the distance, and / or • a measured signal value of a reception signal (12).

11. Laser distance measuring module according to claim 6 to 10, characterized in that the laser distance measuring module is configured in such a way that the ADC (17) generates an ADC sampling pattern by means of at least two ADC conversion stages, wherein • the ADC sampling pattern defines with respect to a reception signal (12) an initial signal sampling pattern with at least one initial sampling point of the reception signal (12), and • the reception signals (12) of the reception signal series are temporally shifted relative to the ADC sampling pattern by means of a first temporal shift, such that the at least one initial sampling point is detected at least once by a first ADC conversion stage and at least once by a second ADC conversion stage, in particular wherein the reception signals (12) of the reception signal series are additionally temporally shifted relative to the ADC sampling pattern by means of a second temporal shift such that in a defined sampling range around the at least one initial sampling point a multiplicity of secondary sampling points of the reception signals arise, said secondary sampling points being shifted in each case by a fraction of the period duration of the ADC clock signal, and this results in the sampling of different signal positions around the at least one initial sampling point with a varying signal value.