Method for readjusting a laser system

Abstract

The invention relates to a method (100) for adjusting a laser system (1), comprising the following steps: - Specifying (101) a time window in which a change of a modulation frequency of the laser system (1) is performed, - Blocking (102) a measurement by the laser system (1) within the specified time window, - Performing (103) the readjustment of the laser system (1) within the specified time window, using a digital-to-analog converter (5) of the laser system to provide precise control of analog signals of the laser system. Furthermore, the invention relates to a computer program, a device and a storage medium for this purpose.

Description

[0001] The invention relates to a method for adjusting a laser system. Furthermore, the invention relates to a computer program, a device, and a storage medium for this purpose. State of the art

[0002] Adjusting a laser system during a measurement process can lead to signal interference, especially with very short measurement times. This interference can occur synchronously, particularly if the laser system's measuring machine and laser control share the same system clock. Such interference can affect the laser system's measurement accuracy. Disclosure of the invention

[0003] The invention relates to a method with the features of claim 1, a computer program with the features of claim 8, a device with the features of claim 9, and a computer-readable storage medium with the features of claim 10. Further features and details of the invention will become apparent from the respective dependent claims, the description, and the drawings. Features and details described in connection with the method according to the invention naturally also apply in connection with the computer program, the device, and the computer-readable storage medium according to the invention, and vice versa, so that mutual reference is always possible with regard to the disclosure of the invention.

[0004] The invention relates in particular to a method for readjusting, especially targeted readjusting, a laser system, comprising the following steps, wherein the steps can be performed repeatedly and / or sequentially. The laser system can, for example, be a laser distance measuring device. Targeted readjustment can refer to the fact that the readjustment is carried out selectively at specific times.

[0005] As a first step, a time window is preferably defined in which a change in the modulation frequency of the laser system is carried out. The modulation frequency refers in particular to the modulated emitted light of a laser of the laser system.

[0006] In a further step, a measurement by the laser system is blocked within the specified time window. This measurement by the laser system specifically concerns the measurement of reflected light during distance measurement, if the laser system is configured as a laser rangefinder. Blocking the measurement can indicate that no sensor data is being acquired during the specified time window, or that acquired sensor data is not being processed or considered.

[0007] In a further step, the laser system is preferably readjusted within the specified time window. This readjustment can be performed, for example, by a measuring controller of the laser system. A signal from a measuring state machine preferably specifies the time window in which the modulation frequencies are to be changed for the measuring controller of the laser distance measuring device. A digital-to-analog converter of the laser system can be set, for example, to provide precise control of analog signals from the laser system. Sensors can continuously monitor parameters such as laser power (i.e., the output power of a laser in the laser system), laser current, temperatures within the laser system, or other control-relevant quantities. This information can be fed back to the measuring controller.Based on this feedback, the measuring controller can adjust the digital control signals that are sent to the digital-to-analog converter.

[0008] The method according to the invention can advantageously prevent or at least reduce disturbances to the measurement caused by the laser system, which arise from readjustment during the measurement.

[0009] Furthermore, within the scope of the invention, it is optionally possible to specify the time window for regularly defined intervals in order to perform the readjustment at these regularly defined intervals. For example, a time window could be provided every 15 ms, which could, for example, have a length of 10 µs.

[0010] Preferably, the defined intervals can be synchronized with a change in the modulation frequency of the laser system during a measurement process. In other words, a time window can be specified for the change between two modulation frequencies in order to perform the adjustments within that window. This ensures that the adjustments are only ever performed during the change in modulation frequency.

[0011] It may be advantageous if, within the scope of the invention, the method further comprises the following step: - Simulating the change in modulation frequency outside the measurement process in order to provide an identical control frequency of the readjustment process inside and outside the measurement process.

[0012] This allows, advantageously, the same configuration set of the measuring controller, i.e., for example, the same filter bandwidth and / or the same gain factor, to be used outside the measurement process as within or during the measurement process.

[0013] For example, the procedure may include the following steps before specifying the time window: - Defining a target value for the laser power of the laser system, - Determining the current laser power of the laser system, - Comparing the current laser power with the defined target value, - Performing readjustment of the laser system if the current laser power exceeds or falls short of the defined target value by a defined amount.

[0014] The target value can be defined to compensate for hysteresis in the laser system, and the time window can only be set once the target value is reached, or once a certain distance within the defined quantity is reached. The defined quantity can also be 1 or zero, meaning that the defined target value itself may need to be exceeded or reached. The current laser power can be determined using a suitable sensor in the laser system.

[0015] A further advantage of the invention can be achieved if the method further comprises the following steps: - Determining a new current laser power after performing the readjustment of the laser system, - Comparing the new current laser power with the defined target value, - Initiating a safe state of the laser system when the new current laser power exceeds or falls short of the defined target value by a defined amount, whereby in the safe state the laser system emits a reduced amount of light, in particular no light.

[0016] This process specifically determines whether a measurement without interference is possible. This allows initial verification of whether the readjustment was successful and the defined target value has now been reached. If not, it may be advantageous to put the laser system into a safe state to prevent potential errors, damage, or hazards. It may also be possible to perform multiple readjustments and comparisons, for example, for a specific number or duration, before initiating the safe state. Subsequently, a manual or automated fault analysis can be carried out. The reduced amount of light is particularly harmless to human eyes.

[0017] The invention also relates to a computer program, in particular a computer program product, comprising instructions which, when executed by a computer, cause the computer to execute the method according to the invention. Thus, the computer program according to the invention offers the same advantages as those described in detail with reference to a method according to the invention.

[0018] The invention also relates to a data processing device configured to execute the method according to the invention. The device can, for example, be a computer that executes the computer program according to the invention. The computer can have at least one processor for executing the computer program. Alternatively, a non-volatile data storage device can be provided in which the computer program is stored and from which the computer program can be read by the processor for execution. The device can also be an analog discrete electronic circuit or an integrated electronic circuit configured to execute the method according to the invention.

[0019] The invention may also relate to a computer-readable storage medium which contains the computer program according to the invention and / or includes instructions which, when executed by a computer, cause the computer to execute the method according to the invention. The storage medium is, for example, designed as a data storage device such as a hard drive and / or non-volatile memory and / or a memory card. The storage medium can, for example, be integrated into the computer.

[0020] Furthermore, the method according to the invention can also be implemented as a computer-implemented method. Alternatively or additionally, at least one of the disclosed method steps can be computer-implemented and / or carried out automatically.

[0021] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination.

[0022] They show: Fig. 1 a schematic visualization of a method, a device, a storage medium and a computer program according to exemplary embodiments of the invention, Fig. 2 a schematic representation of a laser system according to exemplary embodiments of the invention.

[0023] In Fig. Figure 1 shows a method 100, a device 10, a storage medium 15 and a computer program 20 according to exemplary embodiments of the invention.

[0024] Fig. Figure 1 shows in particular an embodiment of a method 100 for adjusting a laser system 1. In a first step 101, a time window is specified in which a change in the modulation frequency of the laser system 1 is performed. In a second step 102, a measurement by the laser system 1 is blocked in the specified time window. In a third step 103, the adjustment of the laser system 1 is carried out in the specified time window, whereby a digital-to-analog converter 5 of the laser system is used to provide precise control of analog signals of the laser system.

[0025] The method of the present invention relates to a laser system 1 and, according to exemplary embodiments, in particular to a laser distance measuring device that uses indirect time-of-flight (iToF) measurement. For this exemplary embodiment, reference is made to Fig.Reference is made to Figure 2. This laser rangefinder 1, for example, operates by measuring the phase shift of a modulated light signal emitted by the laser rangefinder and reflected by a target object. The following describes the operation of the indirect Time of Flight (iToF) measurement. First, a laser 3 in the laser rangefinder 1 emits modulated light, for example in the infrared or visible range, towards a target object. The modulation is achieved, in particular, with a sinusoidal or square wave. The modulated light then strikes the target object and is reflected back to the laser rangefinder 1. A detector 4 in the device can now receive the reflected light. Since the light requires a certain amount of time to travel the distance there and back, a phase shift occurs between the emitted and the received signal.This phase shift between the transmitted and received signal can then be measured. This phase shift is proportional to the distance traveled by the light. The distance can then be calculated from the phase shift, taking into account the wavelength of the modulation and the speed of light. Furthermore, it may be possible to determine a reference phase at a constant distance in order to calculate the phase shift based on a comparison with this reference phase.

[0026] To increase measurement accuracy and range, and to avoid ambiguities in phase measurement, multiple modulation frequencies can be used. For example, two, three, four, eight, or even 16 different modulation frequencies could be used. A measurement state machine, also known as a measurement state automaton, can be used to switch between the modulation frequencies. The measurement state machine is a model used to control and manage measurement processes. It is based on the concept of a state machine, which defines different states and transitions between them. These states represent, for example, different phases or steps in the measurement process, such as initialization, measurement, measurement with a specific modulation frequency, data storage, or error handling.Transitions define how and when the change from one state to another occurs. These are triggered, for example, by events or conditions, such as the arrival of a measurement signal or reaching a time limit. Inputs include, for example, start signals, measured values, or error conditions. Outputs can be actions or reactions of the state machine to a specific state or transition.

[0027] This includes, for example, sending signals, storing data, or triggering alarms.

[0028] The laser distance measuring device 1 can have a measuring controller 2. The measuring controller 2 is responsible, in particular, for controlling the laser 3.

[0029] The measuring controller 2 can control the emission of the laser 3 by regulating the switching on and off as well as the intensity of the laser beam of the laser 3. This ensures that the laser beam is emitted with the correct power and properties.

[0030] Furthermore, a laser beam from laser system 1 can be modulated, for example, in the form of pulsed light and / or a continuous wave with a variable modulation frequency. After the reflected laser beam is received by detector 4, the received signal can be processed. This includes, for example, amplification, filtering, and conversion of the received analog signal into a digital signal for further analysis, in particular by an analog-to-digital converter (not shown). The phase shift between the emitted and received signals can also be measured and, if necessary, compared with the reference phase.

[0031] Furthermore, the measuring controller 2 can perform regular calibrations to ensure that the measurements are precise. For this purpose, it can monitor the condition of the laser 3 and the detector 4 to ensure that they are functioning correctly.

[0032] In the method according to exemplary embodiments of the invention, a signal from a measuring state machine preferably specifies a time window to the measuring controller 2 of the laser distance measuring device 1 during which the modulation frequencies are changed. Measurement cannot be performed during the frequency change. The measuring controller 2 can use this time window to make adjustments. If a measurement is terminated, but the laser 3 continues to operate, a substitute timer in the measuring controller 2 preferably activates and simulates the timing of a measurement process. This allows the adjustment frequency to be identical and the same configuration set (filter bandwidth, gain factor) to be used as during the measurement. If the laser power deviates by a defined amount from a defined target value, the measuring controller 2 preferably activates immediately and attempts to correct the deviation.If it fails to do so, the safety limits already described are preferably exceeded and the laser 3 enters a safe state, the safe state being in particular a safe state in which the laser system 1 does not emit light.

[0033] In particular, it is therefore planned that an alternative clock signal will be generated when the measurement state machine is switched off.

[0034] During the start-up of laser 3, the emitted laser power is still too weak and therefore outside the hysteresis range. A digital-to-analog converter 5 can be continuously adjusted by a corresponding signal as part of the readjustment process. After reaching the defined target value of the laser power, a time window is preferably only enabled during the frequency change, by which the digital-to-analog converter 5 is readjusted.

[0035] The preceding explanation of the embodiments describes the present invention solely by way of examples. Naturally, individual features of the embodiments can be freely combined with one another, provided this is technically feasible, without departing from the scope of the present invention.

Claims

[1] Method (100) for adjusting a laser system (1) comprising the following steps: - Specifying (101) a time window in which a change of a modulation frequency of the laser system (1) is performed, - Blocking (102) a measurement by the laser system (1) within the specified time window, - Performing (103) the readjustment of the laser system (1) within the specified time window, using a digital-to-analog converter (5) of the laser system to provide precise control of analog signals of the laser system. [2] Method (100) according to claim 1, characterized by , that the time window is specified for regular defined intervals in order to carry out the readjustment at the regularly defined intervals. [3] Method (100) according to claim 2, characterized by, that the regular defined intervals are synchronized with a change in the modulation frequency of the laser system (1) during a measurement process. [4] Method (100) according to claim 3, characterized by , that the procedure (100) further comprises the following step: - Simulating the change in modulation frequency outside the measurement process in order to provide an identical control frequency of the readjustment process inside and outside the measurement process. [5] Method (100) according to any one of the preceding claims, characterized by , that the procedure (100) prior to specifying (101) the time window further comprises the following steps: - Defining a target value for the laser power of the laser system (1), - Determining the current laser power of the laser system (1), - Comparing the current laser power with the defined target value, - Performing readjustment of the laser system (1) when the current laser power exceeds or falls short of the defined target value by a defined amount. [6] Method (100) according to claim 5, characterized by , that the procedure (100) further comprises the following steps: - Determining a new current laser power after performing the readjustment of the laser system (1), - Comparing the new current laser power with the defined target value, - Initiating a safe state of the laser system (1) when the new current laser power exceeds or falls short of the defined target value by a defined amount, wherein in the safe state the laser system (1) emits a reduced amount of light, in particular no light. [7] Method (100) according to any one of the preceding claims, characterized by, that the laser system (1) is a laser distance measuring device and the readjustment is carried out by a measuring controller (2) of the laser distance measuring device. [8] Computer program (20) comprising instructions which, when the computer program (20) is executed by a computer (10), cause it to execute the method (100) according to any of the preceding claims. [9] Device (10) for data processing which is configured to carry out the method (100) according to any one of claims 1 to 7. [10] Computer-readable storage medium (15) comprising instructions which, when executed by a computer (10), cause it to perform the steps of the method (100) according to any one of claims 1 to 7.

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