CA1315861C - Modular observation instrument with range finder - Google Patents

Abstract

On the basis of observation field glasses with incorporated infrared range finder, a modular observation instrument is described, in which the infrared optical path of the range finder is guided over the same optical elements , which determine the optical path of the field glasses. Into the instrument casing is additionally integrated at least one direction meter and at least one computer module for the functional control of the measuring processes. There are also means for simultaneously triggering the range finder and the direction meter, the optical path of the visible light remaining undisturbed for the field glasses function during said measuring process, so that the visual representation of the measured object is also unimpaired during the measuring phase. The IR-light is separated from the common optical path directly upstream of the field glasses eyepieces with tile aid of beam splitters. This leads to an effective protection of the eyes, whilst permitting an optimum use of the optical components. The result is a handy measuring instrument for precise three-dimensional tracking of objects, which can be simultaneously visually observed in an undisturbed manner.

Description

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The invention relates to a modular observation instrument with rang~ finder. The invention more particularly relates to a modular, multifunctional observation or viewing instrument, which is able to function as a monocular telescope or binocular field glasses, as an integrated range finder, as a direction meter and optionally further attachments.

Various instruments are known in a combination of field glasses or telescope with a fitted in or on range finder, or provided with a compass. Both types of instrument are provided for various special purposes. However, none of them is able to supply a complete three-dimansional information over the absolute position of a sighted object, e.g. as a mathematical vector, described by a direct distance indication with respect to a reference point and two angular readings (azimuth and elevation).

In addition, geodetic precision range finders using a laser light source are known. Such instruments are mainly used as an attachment to existing geodetic equipment. The use thereof assumes the usage of a target reflector, which reflects the laser pulses emitted by the instrument. Target observation or the identification thereof and the actual measuring process take place in succession.

131~861 For a generally mobile use field glasses-like, usually monocular instruments are known having a built-in range finder. Generally the optical path of the range ~inder is separate from that for the visual observation of the object.
Separate, complicated æpecial optics are used for each part, i.e. for the visible light on the one hand and the observation light, generally infrared light (IR) on the other, so that such instruments have a relatively high weight. The conventional restriction to a single observation channel ~monocular) impairs the coverage for the observer and rapidly leads to fatigue.

The problem of the present invention is to provide a modular observation X - la -instrument with range finder in such a way that it also permits the tracking of an o~ject and offers a significant constructional simplification with the aim of an optimum rational use of the lenses required for the system, so as to in this way be able to save weight and provide a much lighter instrument. In order to be able to clearly determine the coordinates of an object to be tracked, apart from the range, also the two angles azimuth and elevation are to be measured.
In addition, an undisturbed, continuous and easy visual observation of an object is to be ensured and, independently thereof, a very precise location measurement is to be possible at any time, whose true and optionally corrected result can be read off simply and reliably, without visual observation having to be interrupted. To ensure the . 15 efficiency and comfort for visual observation, a binocular instrument is sought.

According to one aspect of the invention there is provided a modular observation instrument comprising a casing containing; an optical viewing device having an erecting prism and having a first optical path defined by a plurality of optical elements; a range finder having a second optical path defined by said optical elements; a direction meter for the azimuth and elevation; at least one computer module having a keyboard for simultaneously triggering the range finder and the direction meter; the erecting prism being provided with selective splitting means for splitting the light into visible light and infrared light.

A preferred embodiment of the invention comprises a modular observation instrument with binocular field glasses and a range finder integrated in a casing with an infrared transmitter and an infrared receiver, in which the infrared optical path of the range finder is passed over the same optical elements which determine the optical path of the field glasses, into the instrument casing are additionally t ~ - 2 -~31~8~i integrated a direction meter for the azimuth and elevation and at least one computer module for the functional control of the measuring processes and means are provided for simultaneously triggering the range finder and direction meter, the optical path of the visible light remaining undisturbed for the field glasses function during this measuring process, so that the visual representation of the measured object is unimpaired during the measuring phase.
Suitably means are provided for repeating the measuring process of range, azimuth and elevation at predetermined intervals and for calculating the vectorial object speed from the thus obtained measured results.

In one embodiment of the present invention the instrument has at least one erecting prism associated with the field glasses, in .~
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which the erectlng prism is provided with selectively reflecting means for splitting up the combined optical path into visible and infrared light directly upstream of the infrare~ transmitter or the infrared receiver. Suitably a beam splitter is fit-ted to the first reflecting face of the erecti.ng prism when considered from objective or lens, so that the interface between the two components is transparent for the infrared light used, whils-t the visible light is reflected in undisturbed manner. Desirabl~ one of the two telescope optics is set up as an infrared transmission channel and the second telescope optics as an in~rared reception channel, a second beam splitter being fitted to the second erecting prism of the field glasses located in the infrared transmission channel and by means of which takes place the direct fading of the infrared transmission radiation into the combined optical path in the direction of the second lens, accompanied by the simultaneous fading of the infrared radiation out of the optical path leading to the second eyepiece. Suitably there are switching means for stabilizing the transmitter in order to ensure the transmission of the directional pulse at a precisely defined time delta t following the application of the triggering pulse.

In another embodiment of the present invention the range finder and the direction meter have autonomous computer modules, whose outputs are combined in common display means. Suitably there is a common display means re~lected into the o~tical path.
Desirably the output of the computer modules are connected with an interface to external signal processing means. Suitably the interface also has connections for the remote initiation of instrument functions.

A decisive advantage of this instrument is the common optics for visual observation and ranging. Thus, the system is simple and is free from excess glass weight. For ranging with pulsed IR-light, use is made of the same optics as for visual observation.
A further decisive advantage of the instrument is that its -2b-t~ .

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multiple function, in particular -the ~hree funckions visual observation, ranging and direction determination can be activated precisely at the same time and not alternatively and successively. This leads to decisive advantages, particularly with respect to the precise tracking of moving targets. The tracking result can be given in absolute coordinate values, if the actual position is known. Through the combination of the individual measures an extremely handy and easily usable instrument is provided, which has a much higher usage value than the hitherto known instruments. The complete combination of said three functions in the case of corresponding design, makes this instrument a highly accurate position finder.

The invention is described in greater detail hereinafter relative to nonlimitative embodiments and the accompanying drawings, wherein show:

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Fig. l the optical path of a binocular observation instrurnent, with tlle representation of the most important optical components.
Fig. 2 the receiver channel according to fig. 1 in slde view.
Fig. 3 the bloclc diagrarn for the electronic par~ of the instrument according to figs. 1 and 2.

The principle of the invention is essentially based on ~lle possibllltyof being able to integrate several functions into one instrument, said instrument having the handiness of field glasses, so that it can be permanently carried by the interested user. Preferably at least three functlons are integrated lnto the instrument, namely the tradltlonal field glasses or telescope func~lon, whlch permits a direct observation of an object, as well as the higl-ly accurate range finding integrated into the observation optical path and as the third function a direction indication also integrated into the instrument and whose result, namely azimuth and elevation~ is additionally projected in the observation optical path. Range and direction measurements can also be transferred to other instruments or, so as to be visible for third parties, can be displayed on the outside of the instrument.

In the present case, a modular construction of the instrument means that it can be designed as a monocular or binocular instrument and that the direction meter can, if deslred, be integrated lnto the lnstrument. The instrument concept permits an adaptation to the particular equipping level in accordance with the desired intended use.

preferred embodiment for illustrating the invention is constituted by the hereinafter described binocular observation instrument, in which one visual channel is additionally used for the transmitter and the other for the receiver of the range finder. ~ccording to fig. 1, it comprises a conventional Eield glasses part with a lens or objectlve 1, an erecting prism 2 for laterally correct imaging and an eyepiece 3. The second optical path also shown in the selected e~lbodiment correspondingly cont-ains a second lens or objective ll, a second erecting prism 12 and a second eyepiece 13. In the two optical paths the path of the visible 1 3 ~

light is indicated by double arrows Sl and SZ. Where necessary, the participating optical faces for the visible range and ~or the range of the measuring radiation used, l.e. in the infrared range for example have been coated.

~dditional components provided in the first optical path are a beam splitter 4 connected to the first erecting prism 2 and a IR-receiver 5.
The beam splitter fades the measuring radiation used ~or the ran~e Elnd-ing out of the combined optical path, so that said part of the radiation does not pass into the first eyepiece 3, except for a residual part which is harmless to the eye. The arrangement of the beam splitter 4 is shown in side view in fig. 2. The interface between beam splitter 4 and erect-; ing prism 2 is provided with a filter layer, which is transparent for the IR-light used, but reflects visible light, so that the traditional effect of the erecting prism remains unchanged for the visible light. Thus, beam splitter 4 is not only used for separating visible and ~R-llght, but also for protecting the human eye against laser radiation.

~part from the conventional components, the second optical path contains a trnnsmitter 15 ior emitting infrared measurement pulses, as well as a second beam splitter 14 combined with the second erecting prism 12. The arrangement of the second beam splitter 14 corresponds to that of the first beam splitter 4 on the first erecting prism 2.

In the preferred embodiment, the IR-light used has a wavelength of approx-imately 900 or 1500 nm, as a function of the laser type used. The IR-trans-mitter comprises e.g. a pulsed or a modulated crystal or semiconductor laser, whosc trnnsmission capacity is sclected in such a way that it relinbly remains within the range protecting the eye, but bridges the desired range. This is optionally achieved by a special signal processing method, which does not form the subject matter of the present invention.
The optical path of the transmitter can in special cases, e.g. when des-igning the instrument as a monocular observation instrument, al90 be led to the outside by a separate optics. In the present case, the reception channel for the IR-radiation is identical with that oE the described instrument. Semiconductor lasers or flash lamps can be used for pumping ~5~

the crystal laser.

The second beam splitter 14 ensures the direct fading of the infrared rndi~ion in~o the conventional erecting prism 12 in thc direction of the second lens 11, accompanied by the simultaneous fading of said radiation out oE the visible optical beam path S2 leading to the second eyepiece 13. By means of the second lens 11, IR-radiation is transmitted in the direction of the object to be measured. The radiation reflected by the object reaches the instrument via the first lens 1, from where it is passed to the first erecting prism 2 and is faded by the first beam splitter 4 out of the combined optical path and is passed to the IR-receiver 5. Unlike in conventional range finders, there is no need to supply the receiver with part of the transmission pulse for fixing the time origin, because corresponding circuitry improvements are prov-ided in the electronic part. These are essentially formed by stabilizing means, which ensure that the directional pulse is always emitted at a precisely deEined time delta t after the application of the triggering pulse. Thus, there is no need for conventional optical cross-connections between transmitter and receiver.

In the simplest case, the IR-receiver 5 can comprise a photodiode and can be integrated together with an amplifier to form a hybrid. Further inte-gration with the analog-digital converter to form an extended hybrid is also possible.

~part from the conventional means, there is also a readout or display 20 and a partly reflecting mirror 21 for reflecting the display values of tlle range finder and direction meter into the optical path to the eyepiece.
On the outside of the instrument it is also possible to provide an auxil-iary display 22.

Finally, there is an assembly 30 for determining the direction of the object to be measured and which will be explained hereinaEter relative to fig. 3.

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~11 the aforementioned parts are placed in a common casing, which is e.g. constructed in similar manner to a conventional casing for field glasses. Despite the additional functions, the observation instrument is extremely handy.

Fig. 3 shows the electronic part and also the functionaL construction of the instrument. In the upper part is provided the range finder and in the lower pnrt the as yet to be described assembly for determining the direction of the sighted object. In principle, the range finder and direction meter are autonomous and are equipped with their own computers.
Tlle outputs of the two assemblies- are led to the common display 20 which, according to fig. 1, is faded into the optical path of preferably only one observation channel.

The display of the measured results takes place in the viewing field ofthe observer and through the readout of the measured results the visual observation process of the object does not have to be interrupted. The measured results can also be displayed on the outside of the instrument.
Switching means for producing the different feed voltages, as well as the batteries are not shown in the drawing.

There is also a keyboard 40 common to the two instrument parts and which is fitted to the outside of the instrument at a readily accessible point.
It is used for initiating the different functions of the instrument and for inputting data. It is positioned in such a way that the observation process is not disturbed during operation. Finally, the instrument can be provided with an interface connection 50 which, according to the preerred embodiment, is also connected to the output of the two instrument parts. The interface can e.g. be standardized and can permlt the connec-tion of the instrument to data transmission means or directly to a computer or mass memory. It can also be used for remotely triggering instrument functions.

The assembly of the range finder with IR-transmitter 15 and IR-receiver5 is connected to a computer module 6, particularly a microprocessor.

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It is preferably an autonomolls mini computer, which is pro~ided with aROM 7 for storing the programs for controlling the assemblies belonging to the range finder and for the exec-ltion of the individual calculating operations. There is also a memory area 8, which is used for the storage oE c1a~n, wllicll c~n on ~hc onc llnn~ ~e prc(lctcr~ ncd cons~nnl:s or rc~crcncedata, e.g. reference coordinates and on the other hand storage locations for storing measured results until they are e.g. polled by interface 50.
The IR-receiver is connected to computer 6 across an analog-dlgital converter 9, the distance being calculated from the signal travelling time. ~s a function of the strength of the signal, individual pulses or pulse sequences are evaluated. Through repeated ranging at short time lntervals, it is possible to measure the speed, particularly the radial speed of the target object.

The second assembly, shown in the bottom part of fig. 3, is a device for direction determination purposes, such as e.g. known from ~P-85 902 429.1.
This device, which is also known as an electronic compass, contains mag-netic sensors 31, tilt sensors 32 and a temperature sensor 33. All three of the latter components are connected across a multiplexer 34 and an analog-digital converter 35 to a second computer 36, particularly a micro~
processor. The latter is also equipped with a ROM 37 and R~M 38. On computer 36, it is possible to see the aforementioned connections to dis-play 20, to keyboard 40 and optionally to interface 50.

In computer 36, the measured data are corrected by means of stored corr-ection tables and by incorporating complimentary and/or redundant sensor informations. Systematic incorrect instructions and interference as a result o temperature influences, declination, installation environment oE the sensors, sloping position, movement, etc., are consequently elimin-ated. Only true quantities are displayed, e.g. the azimuth and elevation.
In addition, plausibility criteria for all the measured values are prog~
rammed in the computer system and they filter out random or temporary disturbances. Computer 36 of the direction meter can also assume addition-al overriding control functions. ~ digital-signal processor (~SP) is particularly advantageous as the range Einder computer 6.

- c3 -F~ LL~ 1. ly, Iu.! Ill~`CI!;U r.Lllg ~ llC i.l) ~ [ L~ i. I'(.'CI: i.OII Ill~!t (`1' i. ': 1)~1';(`(1 on deterrnining the terrestrial magnetic fieLd by means oE magnetic sensor 31 and to correct the measured result with the aid of slope or tilt sensors 32. Finally, using ~he temperature sensor 33, Lhere i9 a comp-ensation of measuring errors caused by temperature changes. 'I'he mag-netic field sensors can be constituted by elements, which are based on the ~lall effect, which incorporate the principle of a field plate, or give rise to a res;stance change, which is then determined with the aid of a bridge circuit.

Measurement with the aid of a dynamic signal is also possible, which issupplied to the sensor briefly and in alternating manner, e.g. in the fonn of a Eurtller magnetic fielc!. The difference of the thus obtained magnetization or the time necessary in order to assume the original position is detennined. The result is a measure for the position of the sensor in the terrestrial magnetic field. Thus, the components of the terrestrial magnetic field and the gravitational field are measured and the azimuth and elevation of the optical axis of the'instrument are calculated therefrom in computer 36, whilst taking account of the stored correction values.

The measured values of the magnetic field sensors are amplified, digitized and processed in computer 36. Details of this device are described in detail in the aforementioned EP-OS ancl are not shown again here. As des-cribed therein, an azimuth measurement performed using said assembly is position and also tilt-independent through the incorporation of tilt sen-sors. In order that the measurement also takes place in an acceleration-independent manner, as from a given rotation angle, there is an automatic switching to the magnetic field sensors for tilt measurement purposes.
The tilt change in space can be calculated by computer 36 and namely as a result of the identification of different and/or uniform signal changes of the magnetic field sensors 31 and by comparison with a previously stored desired value curve.

As a result of the time change of the sensor signals and therefore o~ the three components of the target vector, it is possible to calculate the ~ 3 ~

vectorial speed oE the target object relative to the observer if the-re ls an instrulnent Eollow-~lp ~y tl~e latLer.

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A modular observation instrument comprising a casing containing; an optical viewing device having an erecting prism and having a first optical path defined by a plurality of optical elements; a range finder having a second optical path defined by said optical elements; a direction meter for the azimuth and elevation; at least one computer module having a keyboard for simultaneously triggering the range finder and the direction meter; the erecting prism being provided with selective splitting means for splitting the light into visible light and infrared light.

2. A modular observation instrument according to Claim 1 in which the optical viewing instrument is a monocular telescope.

3. A modular observation instrument according to Claim 1 in which the optical viewing instrument is a binocular.

4. A modular observation instrument according to Claim 3, in which a first of the telescope optics of the binocular constitutes an infrared transmission channel and a second of the telescope optics thereof constitutes an infrared reception channel, and said instrument comprises two of said erecting prisms, each erecting prism being disposed in a respective one of the telescope optics, wherein the splitting means comprises a first beam splitter on the first reflecting face of the erecting prism in the first telescope optic when considered for the objective lens, and said splitting means further comprises a second beam splitter on the erecting in the second telescope optic, whereby the second beam splitter causes direct fading of the infrared transmission radiation into the optical path of said second telescope optic in the direction of the second lens thereof, and further causes optical path of the second telescope optic to the eyepiece thereof.

5. Observation instrument according to claim 4, comprising circuit means for stabilizing the transmitter in order to ensure the transmission of the directional pulse at a precisely defined time delta t following the application of the triggering pulse.

6. Observation instrument according to claim 1, comprising common display means for displaying the output of the range finder and the direction meter, in which the range finder and the direction meter have autonomous computer modules.

7. Observation instrument according to claim 6, in which the common display means is reflected into the optical path.

8. Observation instrument according to claim 6, in which the output of the computer modules are connected with an interface to external signal processing means.

9. Observation instrument according to claim 8, in which the interface also has connections for the remote initiation of instrument functions.

10. Observation instrument according to claim 1, comprising means for repeating the measuring process of range, azimuth and elevation at predetermined intervals and for calculating the vectorial object speed from the thus obtained measuring results.