STABILIZED DISTANCE MEASUREMENT IN THE OBSERVATION DEVICE

• US 20150062557A1
• Filed: 08/28/2014
• Published: 03/05/2015
• Est. Priority Date: 08/28/2013
• Status: Active Grant

• Current Assignee: Safran Vectronix AG (Safran SA)
• Original Assignee: Vectronix AG (Safran SA)
• Inventors: GIACOTTO, Luca
• Granted Patent: US 9,864,061 B2
• Time in Patent Office: Days
• US Class Current: 356/5.01
• CPC Class Codes: F41G 3/02 using an independent line of sight
• CPC Class Codes: F41G 3/06 with rangefinder rangefinders per se G01C
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• 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 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

The invention relates to a portable observation device having an observation path for optical targeting of a target object, and comprising an optoelectronic rangefinder for measuring the distance in the direction of the targeting. The rangefinder includes a transmission unit for emitting a temporal sequence of pulses of optical radiation, a reception unit for receiving a portion of the optical radiation cast back by the target object and for determining signal information and an electronic evaluation unit, which a distance to the target object can be determined on the basis of a signal travel time between emission and reception of the optical radiation. When a trigger is actuated manually, the distance is determined including the signal information from a specified minimum number of pulses, which define a minimum length of a time window of the distance measurement.

Claims

1. A portable observation device comprising an observation path, which, in particular, is unstabilized, for optical targeting of a target object, and comprising an optoelectronic rangefinder for measuring the distance in the direction of the targeting, in particular a laser distance meter with a collimated laser beam as a target axis, comprising:

a transmission unit for emitting a temporal sequence of pulses of optical radiation,

a reception unit for receiving a portion of the optical radiation cast back by the target object and for determining signal information of the cast-back portion of an emitted pulse, and

an electronic evaluation unit, which is embodied in such a way that a distance to the target object can be determined on the basis of a signal travel time between emission and reception of the optical radiation,

wherein the distance is determined including the signal information from a specified minimum number of pulses,

which minimum number defines a minimum length of a time window (twd) of the distance measurement, and comprising

a trigger which can be actuated manually and the actuation of which causes a start of the time window (twd) of the distance measurement,

wherein

the observation device

comprises a movement sensor for acquiring an instability of a spatial position of the observation device and

an actuation unit of the rangefinder, which is embodied in such a way that the rangefinder is controlled on the basis of spatial position data from the movement sensor in such a way that the pulses counting as part of the minimum number satisfy predetermined criteria in respect of these spatial position data assigned in time.

2. The observation device according to claim 1, wherein

the minimum number

is predetermined as a fixed number or else determined dynamically depending on a signal quality of the reception,

in particular wherein the minimum number is defined as that number of pulses at which a minimum signal-to-noise ratio limit value is reached when determining the distance.

3. The observation device according to claim 1, wherein

the instability is acquired in the form of an oscillation in a spatial direction of the targeting, in particular an oscillation caused by trembling movements of a hand holding the observation device, and

control is brought about on the basis of a criterion, according to which, in order to include the signal information, a current oscillation value assigned thereto in time lies in a predetermined range about a central region of the oscillation.

4. The observation device according to claim 3, wherein

the central region of the oscillation is a mean value of the movement over a defined period of time before or after a time at which the trigger is actuated.

5. The observation device according to claim 3 or 4, wherein

the predetermined range about the central region of the oscillation (24a, 25a) is set with dynamic or statistical dependence on an amplitude of the oscillation,

in particular as a percentage, which can be set by the user, of a maximum value of the amplitude or as a percentage of a standard deviation of the amplitude of the oscillation.

6. The observation device according to claim 1, wherein

the control actuates the transmission unit, depending on the spatial position data from the movement sensor, in such a way

that the pulses of the optical radiation are only emitted in a defined directional range about the targeted target object.

7. The observation device according to claim 1, wherein

the control actuates the reception unit depending on the spatial position data from the movement sensor in such a way

that only portions of the optical radiation cast back from a defined directional range about the targeted target object are received.

8. The observation device according to claim 1, wherein

the control actuates the evaluation unit depending on the spatial position data from the movement sensor in such a way that the distance is only established including portions of the optical radiation cast back from a defined directional range about the targeted target object,

in particular wherein, during the time window, a memory of the evaluation unit records the signal information and the spatial position data assigned in time to emission and/or reception and the determining process is performed using a spatial position data-dependent directional evaluation of the signal information.

9. The observation device according to claim 1, wherein

the observation path is configured as an optical transmitted light path from an objective to an eyepiece, in particular wherein the transmitted light path is unstabilized and the observation device provides an unstabilized observation image in the eyepiece.

10. The observation device according to claim 1, wherein

the observation device is embodied with

a sighting apparatus in the observation path of the observation device, by means of which a targeting direction is defined,

a residual light amplifier,

a superposition of display images into the observation path,

a deflection of camera images from the observation path,

an angle measurement unit,

a true-north determination unit,

an inclination determination unit and/or

a geographic coordinate determination unit (GPS),

in particular wherein an acquisition of data from at least one of the aforementioned units on the basis of the predetermined criteria is controlled.

11. A. distance measuring method using a portable distance measuring observation device, comprising the following steps:

targeting a target object with an observation path, in particular an optical transmitted light path from an objective to an eyepiece of the observation device,

triggering a distance measurement in the direction of the targeting by manual actuation of a trigger, causing the start of the time window of the distance measurement,

emitting a temporal sequence of pulses of amplitude-modulated optical radiation, in particular laser light, in the direction of the targeting using a transmission unit,

receiving a portion of the optical radiation, which is cast back by a target object, using a photosensitive electrical component, and determining signal information of the received optical radiation using a reception unit,

determining a distance to the target object on the basis of a signal travel time between emission and reception of the optical radiation using an electronic evaluation unit, wherein the distance is determined including the signal information from a specified minimum number of pulses,

which minimum number defines a minimum length of a time window of the distance measurement,

wherein

acquiring an instability of a spatial position of the observation device using a movement sensor and, by using an actuation unit, controlling the distance measurement on the basis of spatial position data from the movement sensor in such a way that the pulses counting as part of the minimum number satisfy predetermined criteria in respect of these spatial position data assigned in time.

12. The distance measuring method according to claim 11, wherein

predetermining a fixed number for the minimum number, or

dynamically determining the minimum number depending on a signal quality of the reception, in particular wherein reaching a minimum signal-to-noise ratio limit value defines the minimum number when determining the distance.

13. The distance measuring method according to claim 11,

wherein

the instability is acquired as an oscillation in a spatial direction of the targeting, in particular an oscillation caused by trembling movements of a hand holding the observation device,

and the control is brought about on the basis of a criterion, according to which, in order to include the signal information, a current oscillation value assigned thereto in time lies in a predetermined range about a central region of the oscillation, in particular wherein the central region is determined as a mean value of the oscillation over a defined period of time before or after a time at which the trigger is actuated.

14. The distance measuring method according to claim 11, wherein

the control is brought about in such a way that

the pulses are only emitted in a defined directional range about the targeted target object,

only portions of the optical radiation cast back from a defined directional range about the targeted target object are received and/or

the distance is only determined including portions (12) of the optical radiation cast back from a defined directional range about the targeted target object.

15. A computer program product with program code, which is stored on a machine-readable medium or a computer data signal, embodied by an electromagnetic wave, for carrying out the method according to claim 11, wherein the program code determines a distance to the target object and controls the distance measurement on the basis of spatial position data from the movement sensor, especially if the program code is executed in a control unit of an optoelectronic rangefinder in an observation device.