DISTANCE MEASURING DEVICE

• US 20130235366A1
• Filed: 03/07/2013
• Published: 09/12/2013
• Est. Priority Date: 03/07/2012
• Status: Active Grant

• Current Assignee: ‎Vectronix AG
• Original Assignee: ‎Vectronix AG
• Inventors: GIACOTTO, Luca, Tinivella, Riccardo
• Granted Patent: US 9,103,669 B2
• Time in Patent Office: Days
• US Class Current: 356/5.01
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487

Abstract

An optoelectronic distance measuring device is disclosed. The device has a transmitting unit with a driver stage for emitting optical pulses, a receiving unit for receiving a portion of the optical pulses, said portion being reflected from a target object, and converting it into an electrical reception signal, via a photosensitive electrical component. It also has an analogue-digital converter for digitizing the reception signal, and an electronic evaluation unit to ascertain a distance from the target object on the basis of a signal propagation time using the digitized reception signal. The driver stage can be designed so that at least two pulse durations of different length for the optical pulses can be set.

Claims

1. An opto-electronic distance measuring device, particularly a laser distance measuring device, having:

a transmitting unit having a driver stage for a light source, particularly a semiconductor light source, for emitting optical pulses as pulsed-mode-intensity-modulated optical radiation,

a receiving unit for receiving a portion of the optical radiation, said portion being reflected from a target object, and converting it into an electrical reception signal, by means of a photosensitive electrical component, particularly a photodiode,

an analogue-digital converter for digitizing the reception signal, and

an electronic evaluation unit which is designed in such a way that a distance from the target object can be ascertained on the basis of a signal propagation time using the digitized reception signal,

wherein

the driver stage is designed in such a way that at least two pulse durations of different length for the optical pulses can be set,

particularly wherein extension of the pulse duration allows expansion of a distance measurement range, as a maximum ascertainable distance, to be achieved.

2. The distance measuring device according to claim 1, wherein the electronic evaluation unit is designed in such a way that the setting of the pulse duration is taken as a basis for using a, in particular, digital, configurable filter to set a bandwidth for the, in particular digitized, reception signal, particularly wherein extension of the pulse duration involves reduction of the bandwidth, specifically extension of the pulse duration involves lowering of an upper cutoff frequency for a low-pass-filter characteristic of the filter.

3. The distance measuring device according to claim 1 wherein

the distance measuring device provides a first mode of operation having a first pulse duration and at least one second mode of operation having a second pulse duration, wherein the first pulse duration is shorter than the second, particularly wherein one of the modes of operation can be selected by a user.

4. The distance measuring device according to claim 1 wherein

the transmitting unit is designed in such a way that the pulse duration is set on the basis of an at least coarsely ascertained or estimated distance from the target object, particularly wherein the distance measuring device is designed in such a way that the pulse duration is set to be longer for long distances than for short distances, specifically wherein a distance threshold being exceeded by the ascertained distance automatically involves extension of the pulse duration in comparison with that for a distance below the distance threshold.

5. The distance measuring device according to claim 1 wherein

the driver stage is a pulse output stage which is designed in such a way that the pulse duration can be set variably independently of a pulse amplitude of the optical pulses,

particularly wherein prescribed values of the pulse amplitude and of the pulse duration can each be set independently of one another.

6. The distance measuring device according to claim 1 wherein

the driver stage has a connectable capacitor for storing a pulse energy, wherein by connecting the capacitor the pulse duration can be set.

7. An observation apparatus having a distance measuring device according to claim 1, having a targeting device for sighting the target object, wherein an optical axis of the targeting device points in the same direction as an optical axis of the distance measuring device, particularly wherein the observation apparatus is designed in such a way that a first mode “

high distance accuracy”

or a second mode “

long measurement distance”

of the distance measuring device can be selected using respective different pulse durations.

8. The observation apparatus according to claim 7, which has an automatic mode which is designed in such a way that the variable setting of the pulse duration takes place automatically in accordance with a characteristic of the reception signal, particularly in accordance with an evaluatability of reception pulses in the reception signal and a signal-to-noise ratio that can be achieved therefor.

14. The method for flexibly matching a distance resolution capability of an optoelectronic distance measuring device according to claim 1 on the basis of distance, comprising

matching of a pulse duration of an emitted optical transmission signal from the distance measuring device on the basis of an ascertained or ascertainable distance, particularly comprising automatic extension of the pulse duration for relatively long distances by means of an evaluation unit, particularly comprising matching of a bandwidth of a reception signal, which is used for ascertaining the distance, to the pulse duration.

9. A distance measuring method comprising:

emission of pulsed-mode-amplitude-modulated optical radiation, particularly laser light,

reception of a portion of the optical radiation, said portion being reflected from a target object, by means of a photosensitive electrical component which converts the received optical radiation into an electrical reception signal,

digitization of the reception signal by means of an analogue-digital converter, and

ascertainment of a distance from the target object on the basis of a signal propagation time by means of evaluation of the digitized reception signal by means of an electronic evaluation unit,

wherein

one of at least two adjustable pulse durations of different length for the optical radiation is selected, which allows a maximum value for the ascertainable distance to be altered, particularly wherein extension of the pulse duration increases the maximum value.

10. The distance measuring method according to claim 9, wherein the distance is ascertained by means of configurable filtering of the reception signal, which filtering is configured in accordance with the set pulse duration in such a way that a bandwidth for the reception signal is matched to the set pulse duration, particularly wherein the bandwidth is decreased towards longer pulse durations.

11. The distance measuring method according to claim 10, wherein besides the pulse duration being set the pulse amplitude is also set, particularly wherein the pulse duration and the pulse amplitude can each be set independently of one another.

12. The distance measuring method according to claim 9 wherein

the pulse duration is set on the basis of the distance, particularly wherein a longer pulse duration is set for a distant target object at a relatively long distance than for a close target object at a shorter distance, specifically wherein the set pulse duration is automatically matched to the ascertained distance, particularly wherein the pulse duration is extended as distance increases, specifically wherein the pulse amplitude is kept constant.

13. The distance measuring method according to claim 9, wherein

a selection is made between

a first mode “

accurate measurement”

with emission of the optical pulses with a shorter pulse duration than in

at least one second mode “

long measurement”

with emission of the optical pulses with a longer pulse duration than in the first mode.

15. A computer program product having program code, which is stored on a non-transitory machine-readable storage medium, embodied by an electromagnetic wave, for carrying out the method according to claim 9, particularly wherein the program code varies a maximum measurement distance of the optoelectronic distance measuring method by setting a pulse duration for optical radiation emitted in pulsed fashion, and preferably also performs bandwidth matching for the reception signal when the distance is ascertained, specifically when the program code is executed in an evaluation unit of an optoelectronic distance measuring device.