JP2010281739A - Laser range finder device and laser range-finding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To install a pointing reference in a scanning range by a simple configuration. <P>SOLUTION: In a laser range finder device for scanning two-dimensionally a laser beam with first and second mirrors, wherein the second mirror on the transmission side of the laser beam is a mirror through which the laser beam is partially transmitted, furthermore includes: a third mirror for reflecting to the second mirror, a laser beam for reference transmitted through the second mirror; a condensing optical system for condensing the laser beam for reference reflected by the third mirror, and reflected by the backside of the second mirror; and a two-dimensional array-shaped detector for detecting the laser beam for reference condensed by the condensing optical system. In the laser range finder device, displacement from a specified value is calculated, based on angle information of the first mirror and the second mirror and on a detection signal from the detector, and each angle of the first mirror and the second mirror is calibrated, based on the displacement. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser distance measuring device and a laser distance measuring method, and more particularly to a laser distance measuring device and a laser distance measuring method for rendezvous docking.

  Although unmanned transport aircraft that transport goods to the space station are being developed in various countries, unmanned docking technology has little track record and high accuracy and high reliability are required. For this purpose, a function for confirming soundness on the orbit is essential, and it is important to have a unique angle reference and perform soundness confirmation and angle calibration whenever necessary.

  On the other hand, in the above-mentioned transport aircraft, the resource requirements for the mounted products are severe, and a large-scale device is impossible due to restrictions on power and weight, and it is expected to achieve the above functions with the minimum necessary components.

  From such a background, a method of measuring using a laser range finder has been proposed. For example, in Patent Document 1 below, an optical fiber for distance calibration as an internal reference and an angle calibration within a scanning range of a scanner are proposed. A scanning laser distance measuring device having a laser beam scanner including an optical fiber having an incident reference position as an incident position is disclosed.

JP 2007-20636 A

  In the scanning pulse laser range finder using the scanner, there is a problem that the pointing of the transmitted light changes from the initial value due to the vibration environment or the thermal environment. When this laser distance measuring device is used on the ground, the above error can be calibrated using an external reference target or the like, but when used in outer space, a reference cannot be prepared outside. There are many cases. For this reason, it is considered to use an internal reference.

  When an internal reference is used for angle calibration, a reference light source is prepared in addition to the distance measuring light source, or when a transmission beam is used, the reference light is out of the required scanning range. It is necessary to install a detector. However, in the former (Patent Document 1), it is unclear whether the original pointing of the transmission beam is really correct, and in the latter, there is a problem that it cannot be a reference of a scanning range that originally requires accuracy.

  The present invention has been made in view of the above problems, and its main purpose is to use a laser range finder capable of setting a pointing reference in a scanning range with a simple configuration and the laser range finder. It is to provide a laser ranging method.

  In order to achieve the above object, the present invention provides a laser range finder that scans a laser beam two-dimensionally with a first mirror and a second mirror, wherein the second mirror on the laser beam transmission side includes: A mirror that partially transmits a laser beam; a reference laser beam that has passed through the second mirror; a third mirror that reflects the second mirror; the third mirror that reflects the reference laser beam; A condensing optical system for condensing the reference laser beam reflected by the back surface of the two mirrors, and a two-dimensional array detector for detecting the reference laser beam condensed by the condensing optical system; , And calculating a displacement amount from a specified value based on angle information of the first mirror and the second mirror and a detection signal of the detector, and based on the displacement amount, the first mirror Mirror and is intended to calibrate the angle of the second mirror.

  According to the laser distance measuring device and the laser distance measuring method of the present invention, a pointing reference that has conventionally been used only with two light sources or outside the scanning range of the device can be installed in the scanning range of the device with a simple configuration. It is possible to detect the pointing of the transmission beam for distance measurement itself. Further, the scanning angle can be calibrated based on the detection signal.

It is a block diagram which shows the structure of the laser ranging apparatus with a pointing reference function based on one Example of this invention. 1 is a perspective view showing a schematic configuration of a two-axis scanner of a laser distance measuring device according to an embodiment of the present invention. It is a figure which shows the example of arrangement | positioning of the optical system of the laser rangefinder which concerns on one Example of this invention. It is a figure which shows the principle of the pointing reference detector which concerns on one Example of this invention.

  As shown in the background art, a method using a laser range finder has been proposed as a measuring instrument used when a transport aircraft is docked to an artificial satellite or a space station. This laser distance measuring device uses an internal reference because the pointing of the transmitted light changes from the initial value due to the vibration environment or thermal environment, but a reference light source is prepared in addition to the distance measuring light source. In this case, it is not known whether the pointing of the original transmission beam is really correct, and when using the transmission beam, it is necessary to install a reference photodetector outside the required scanning range, which is inherently accurate. However, there is a problem that it is not a reference for a necessary scanning range.

  Therefore, in the present invention, a laser ranging device mounted on the transport aircraft side scans a laser with a satellite or a space station marker (corner cube reflector, etc.) with a two-dimensional scanner, and is obtained from the round trip time of the pulse laser. The position of the marker is calculated from the distance information and the angle information of the scanner, and in the laser distance measuring device that guides the transport aircraft, angle deviations that change due to environmental conditions such as vibration and impact at the time of launch are detected, and the soundness of accuracy is improved. In addition to being detected, in the event of a deviation, it can be used as an angle calibration value.

  Specifically, by using a pointing reference optical system and a pointing detector, a deviation from the initial value is detected, and in the unlikely event, it is used as an angle calibration value to the scanner unit. The pointing reference optical system has a function of reflecting the partially transmitted light of the transmission beam from the scanner mirror and returning it to the scanner unit again. The transmitted light of the scanner mirror made of parallel flat glass does not affect the pointing even if the scanner angle is changed. For this reason, the partially transmitted light means that the pointing information of the beam incident on the scanner mirror is held. If the beam incident on the scanner mirror deviates for some reason, the pointing of the partially transmitted beam deviates from the previously acquired angle even if the scanner unit is set to the previously measured angle. End up. By detecting this shifted pointing with a pointing detector using, for example, a four-quadrant photodetector, the difference from the initial value can be found. Further, by incorporating the difference from the initial value into the offset information of the scanner, it can also be used as a calibration value.

  In order to describe the above-described embodiment of the present invention in more detail, a laser distance measuring apparatus and a laser distance measuring method according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a laser range finder having a pointing reference function according to an embodiment of the present invention, and FIG. 2 is a perspective view showing a schematic configuration of a biaxial scanner of the laser range finder. is there. FIG. 3 is a diagram showing an arrangement example of the optical system of the laser distance measuring device, and FIG. 4 is a diagram showing the principle of the pointing reference detector.

  As shown in FIG. 1, a laser distance measuring device 10 having a pointing reference function according to the present embodiment includes a laser 11, a transmission / reception optical unit 12, a scanner unit 13, a scanner driving unit 14, a light receiving unit 15, a distance measuring counter unit 16, The level detection unit 17, the pointing reference optical system 18, the pointing detector 19, the control unit 20, the power supply unit 21, and the like are included.

  The laser 11 emits a pulse laser. The transmission / reception optical unit 12 shapes the transmission beam and transmits the received light to the light receiving unit 15. The scanner unit 13 scans the laser beam two-dimensionally and partially transmits a part of the transmission light. The scanner driving unit 14 transmits an angle command signal to the scanner. The light receiving unit 15 detects transmitted / received light and converts it into an electrical signal. The ranging counter unit 16 counts the time between transmission and reception pulses from the transmission and reception pulses from the light receiving unit 15. The level detector 17 detects the level of the received pulse. The pointing reference optical system 18 transmits the partially transmitted light of the scanner to the pointing detector 19. The pointing detector 19 detects the pointing of the transmission beam from the partially transmitted light of the transmission light transmitted from the pointing reference optical system 18. The control unit 20 calculates the difference from the initial value from the angle information of the scanner and the pointing detection signal from the pointing detector 19, and calibrates the scanner angle when a deviation occurs. The power supply unit 21 supplies power to these units.

  As shown in FIGS. 2 and 3, the scanner unit 13 includes two mirrors (fast axis mirror and slow axis mirror) that two-dimensionally scan the laser beam, and the slow axis mirror is a part of the transmitted light. It functions as a partially transmissive mirror 13a that partially transmits the part.

  The pointing reference optical system 18 collects a beam on the detection surface of a mirror (facing mirror 18a) that reflects the partially transmitted light from the partial transmission mirror 13a and a pointing detector 19 (such as a four-quadrant detector). A condensing optical system that emits light (condensing lens 18b) is provided. When the fast axis mirror and the slow axis mirror of the scanner unit 13 are set to the reference position, the normal line of the facing mirror 18a coincides with the optical axis of the laser beam reflected by the fast axis mirror, and the condenser lens 18b and The optical axis of the pointing detector 19 coincides with the optical axis of the laser beam reflected by the slow axis mirror.

  Next, an outline of the operation of the laser distance measuring device 10 of the present embodiment will be described.

  First, a normal laser ranging operation will be described.

  The pulse output from the laser 11 shapes the beam by the transmission / reception optical unit 12 and transmits it to the scanner unit 13. In the scanner unit 13, angle information can be obtained by scanning the beam in two axes. The reflected light from the target is received, converted into an electrical signal by the light receiving unit 15, and the transmitted light pulse at the time of laser emission. By counting the time, the distance to the target can be measured, and three-dimensional information can be obtained from the biaxial angle and distance information.

  Next, the pointing reference function will be described.

  As shown in FIGS. 2 and 3, a part of the beam reflected by the mirror of the scanner unit 13 and transmitted to the target is transmitted to the pointing reference optical system 18 using the partially transmitted light of the scanner mirror. This partially transmitted light is reflected by the facing mirror 18a and transmitted again to the scanner mirror (partially transmissive mirror 13a). Then, it is reflected again by the back surface of the scanner mirror (the surface opposite to the transmission mirror surface), and is condensed on the light detection surface of the pointing detector 19 by the condenser lens 18b.

  The position of the condensing point has pointing information of the transmission light, and the pointing of the transmission light can be confirmed by detecting the position of the condensing point with a four-quadrant photodetector or the like. The pointing of the transmitted light changes with the angle of the scanner, but the pointing detection beam reflected on the back of the scanner mirror also changes at the same time, and the relationship between the scanner angle and the position of the focal point on the pointing detector is initial. Can be recorded as a value. By comparing the recorded initial value with the soundness confirmation data on the orbit, it is possible to use it for the determination of abnormality and the calibration value.

  Next, the operation of the pointing detector 19 will be described. Here, a case where a four-quadrant photodetector is used will be described as an example. A similar operation can be performed using a two-dimensional array sensor such as a CCD (Charge Coupled Devices).

  As shown in FIG. 4, the laser beam reflected by the back surface of the scanner mirror (partially transmissive mirror 13a) is collected by a pointing reference optical system 18 and input to a four-divided photodetector, and converted into a four-channel electrical signal. Convert. The converted analog signal is A / D converted, and the direction of the laser beam is detected from the distribution of the signal intensity of the four channels. The quadrant PD is installed so that the two axes (fast axis and slow axis) of the scanner are in the direction shown in the figure. From each output of the quadrant PD, the control unit 20 outputs a fast axis error signal and a slow axis error signal by the following processing.

Difference between A + B and C + D = fast axis error signal δVfast (unit: V)
Difference between A + D and B + C = slow axis error signal δVslow (unit: V)

  Then, the error signal is A / D converted, and the error signal is corrected using the angle information of the two mirrors of the scanner unit 13 so that the error signal is equal to or less than a predetermined value. The obtained reference values (values when the two mirrors are used as reference positions) are compared, and the fast axis and slow axis of the scanner are controlled, respectively, so that the difference is equal to or less than the specified value. The control angles of the fast axis and the slow axis at this time are pointing displacement amounts Δθfast and Δθslow, respectively.

  As described above, the mirror on the beam transmission side of the scanner unit 13 is the partially transmissive mirror 13a, the facing mirror 18a that reflects the partially transmitted light, and the reflected light that is reflected by the facing mirror 18a, and the back surface of the partially transmissive mirror 13a. A condensing lens 18b for condensing the beam reflected by the condensing lens and a two-dimensional array of photodetectors for detecting the beam condensed by the condensing lens 18b. By calculating the difference from the initial value from the pointing detection signal, the deviation can be detected, and the scanner angle can be calibrated when the deviation has occurred.

  In addition, this invention is not limited to the said Example, The structure and control method can be changed suitably, unless it deviates from the meaning of this invention.

  INDUSTRIAL APPLICABILITY The present invention can be used for a transport aircraft that performs rendezvous docking on an artificial satellite or a space station, and a satellite for on-orbit service.

DESCRIPTION OF SYMBOLS 10 Laser distance measuring device 11 Laser 12 Transmission / reception optical part 13 Scanner part 13a Partially transmissive mirror 14 Scanner drive part 15 Light receiving part 16 Distance counter part 17 Level detection part 18 Pointing reference optical system 18a Directly facing mirror 18b Condensing lens 19 Pointing Detector 20 Control unit 21 Power supply unit

Claims (6)

In a laser range finder that scans a laser beam two-dimensionally with a first mirror and a second mirror,
The second mirror on the transmission side of the laser beam is a mirror that partially transmits the laser beam;
A reference laser beam transmitted through the second mirror is reflected by the second mirror, and the reference laser beam is reflected by the third mirror and reflected by the back surface of the second mirror. A condensing optical system for condensing the laser beam, and a two-dimensional array detector for detecting the reference laser beam condensed by the condensing optical system,
A displacement amount from a specified value is calculated based on angle information of the first mirror and the second mirror and a detection signal of the detector, and the first mirror and the second mirror are calculated based on the displacement amount. A laser distance measuring device characterized by calibrating the angle of the mirror. When the first mirror and the second mirror are set to a reference position,
The normal line of the third mirror coincides with the optical axis of the laser beam reflected by the first mirror;
2. The laser range finder according to claim 1, wherein optical axes of the condensing optical system and the detector coincide with an optical axis of the laser beam reflected by the second mirror.   The laser range finder according to claim 1, wherein the laser range finder is installed in a transport aircraft that is unattendedly docked on an artificial satellite or a space station. A laser ranging method using a laser ranging device that scans a laser beam two-dimensionally with a first mirror and a second mirror,
The second mirror on the laser beam transmission side is a mirror that partially transmits the laser beam,
A reference laser beam transmitted through the second mirror is reflected by the second mirror, and the reference laser beam is reflected by the third mirror and reflected by the back surface of the second mirror. A condensing optical system for condensing the laser beam, and a two-dimensional array detector for detecting the reference laser beam condensed by the condensing optical system,
A displacement amount from a specified value is calculated based on angle information of the first mirror and the second mirror and a detection signal of the detector, and the first mirror and the second mirror are calculated based on the displacement amount. A laser ranging method characterized by calibrating the angle of the mirror. When the first mirror and the second mirror are set to a reference position,
The normal line of the third mirror coincides with the optical axis of the laser beam reflected by the first mirror;
The laser ranging method according to claim 4, wherein optical axes of the condensing optical system and the detector coincide with an optical axis of the laser beam reflected by the second mirror.   The laser range finder is installed in a transport aircraft that is unattended docked to an artificial satellite or space station, and a laser beam reflected by the marker of the artificial satellite or the space station is detected, and the position of the marker is specified. The laser ranging method according to claim 4 or 5, wherein

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