Optical device for detecting a light beam reflected on a distant target

The present invention relates to an optical device for detecting a light beam reflected at a long-range target, comprising a light source, which is designed to send the light beam in a predetermined direction towards the long-range target, a primary lens, whose optical axis is substantially parallel to said predetermined direction and which is adapted to to focus the long-range reflected light beam at a first focal point, and a detector unit for detecting focused light.

Such optical devices are used, for example, in laser measurement technology, in which a laser beam is emitted, reflected at a long-range target, and its reflection is registered in a detector. The difference between the transmission time and the reception time can then be used to deduce the distance to the long-distance destination.

To register the remotely reflected light beam in a detector, the incident light beam is focused. For this purpose, a so-called primary lens is arranged in the beam path of the remotely reflected light beam, which focuses the remotely reflected light beam on a focal point in which the detector is arranged. Because long-distance goals

WEISER & VOITH PATENTANWÄLTE PARTNERSHIP · FN 463913A · KOPFGASSE 7 · A-1130 VIENNA · WWW.PATENTE.NET TEL +43 (1) 8791706 · FAX +43 (1) 8791707 · MAIL @ PATENTF / NFT · IBAN AT102011100003856704 · BIC GIBAATWW · ATU71838648 are far removed in relation to the size of the optical device, the beam directions of the emitted light beam and the far-end reflected light beam may be considered to be parallel.

However, a problem with such optical devices is that the emitted light beam is reflected not only by the far end to be measured, but also by disturbing "near targets in the air, such as dirt particles or insects. The reflected light rays from such disturbances are registered by the detector and provide for unwanted results or measurement errors.

It is known from the prior art to solve this problem by determining, based on the transit time of the light beam, which reflections originate from the near range, such as described in WO 2016/173711 A1. As a result, short-range reflections determined in this way can then be mathematically deleted from the overall result of the reflections. However, these computational solutions are particularly unsuitable for "multiple-time-Around capable laser scanners in which multiple laser pulses are simultaneously on the way between the light source and the long-term, whereby a direct assignment of results to maturities is limited.

The invention has for its object to provide a device which overcomes these problems and enables an improved measurement of long range targets.

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The invention provides for this purpose an optical device of the aforementioned type, in which the detector unit is arranged such that the first focal point between the primary lens and the detector unit is located, wherein a diaphragm within a normal to the optical axis cross-section of the remotely reflected light beam between the first focal point and the detector unit is arranged.

The invention solves the problem of undesirably detected short-range targets by attenuating the near-field sensitivity of the optical device, and achieves this by employing a shutter which acts distance-selective between the first focus and the detector unit. The spacing of the detector unit from the first focal point, for example at a predetermined distance of at least 100 μm, in this case creates the additional path length required for the diaphragm according to the invention in the beam path of the light beam reflected in the long-term direction.

By the aperture, the possibility is created to hide a higher proportion of near-reflected compared to distant-reflected light by the aperture is in the range of the focal points of the near-target reflected light beams.

The invention thus provides a system which blocks reflections from the near field already in front of the detector so that the result output from the detector has a higher weighting of far-reflected light beams to near-reflected light beams. Calculated evaluations and processing of the detector output are thus no longer required for the processing of the measured value result.

The optical device according to the invention can be used in many fields of the prior art, in which an active system performs the illumination and a detector records the illumination reflection, for example in a camera with light source for illuminating a scene. In these cases, the light source may be arranged in any closer environment of the primary lens.

However, the light source in the beam direction of the remotely reflected light beam is particularly preferably arranged in the beam path in front of the primary lens, and the diaphragm lies in that shadow of the light source which the light source casts in the light beam reflected in the long-range. In particular, in the laser measurement technique, the light source is often placed directly in front of the primary lens to coaxially couple their light rays in the beam path of the incident light rays, either by using a small deflection mirror in the middle of the primary lens, via which a light source is coupled laterally, or by a small light source, eg a laser diode is placed directly in front of the primary lens. The light source inevitably blocks some of the total incident light at this position, including the desired far-end reflected light rays and the undesired near-end reflected light rays.

The invention exploits this fact and positions the diaphragm in this shadow cast by the light source, but with a distance-selective effect between the first focal point and the detector unit. As a result, as compared with prior art lens systems having a light source located in front of the primary lens, there is no decrease in useful remote target reflected light beams, while the effect of reducing the near target reflection is entirely maintained.

In the mentioned embodiment, the diaphragm assumes the said shadow completely in the mentioned cross section. This results in maximizing the near-end reflected light beams blocked by the shutter, and the far-end reflected light beams are not affected by the shutter.

Particularly preferably, at least one further diaphragm is arranged within a further cross section, which is normal to the optical axis, of the remote-controlled light beam between the first focal point and the detector unit. This is particularly advantageous when diaphragms are used, which are thin compared to the distance between the first focal point and the detector unit, for example disc-shaped apertures. If only a thin disk stop is used, it may happen that light beams reflected near the target cross the optical axis in front of or behind the stop and are therefore perceived by the detector. The use of several consecutive apertures along the optical axis minimizes this effect, further reducing near-field sensitivity.

If a plurality of diaphragms are used, it is advantageous if the diaphragms have different areas in cross-section and their area is greater, the farther the respective diaphragm is spaced from the first focus. As a result, the diaphragm shape can be adapted to the beam path of the remotely reflected light beam, whereby the detected far-reflected light component does not diminish. Consequently, only near-target reflected light beams are blocked.

Preferably, the diaphragm is an opaque structure carried by a glass plate. This maximizes the amount of exploitable, long-range reflected light since the glass plate allows the far-sighted light to pass unhindered in those areas where the opaque structure is not embedded in or onto the glass plate. In particular, no disturbing webs or the like is needed to position the aperture.

The shape of the panel itself can basically be arbitrary. Preferably, it is adapted to the shadows thrown by the light source in the long-range reflected light beam. Thus, in principle, apertures with a rectangular, pillow-shaped or oval cross-section are conceivable. Particularly preferably, the diaphragm / 41 is a round disc, since this is easy to manufacture and model their effect well for computational simulations.

Also in the direction of the optical axis, the aperture can be designed differently, eg instead of a disc shape in rod form or conical shape, again any cross sections can be used as described above. Preferably, the diaphragm is a cone or a truncated cone, which widens in the beam direction of the remotely reflected light beam. This corresponds, as it were, to a "continuum of successive, infinitesimally thin disk apertures with progressively larger diameters, which increases the blocking of near-target reflected light beams as compared to discrete single apertures or bar apertures.

Preferably, in this embodiment, the opening angle of the cone is substantially adapted to the beam path of the remotely reflected light beam. This achieves a particularly high yield of far-sighted light in the detector with a maximum reduction in near-end reflected light.

The aperture or the aperture closest to the first focal point is preferably arranged at a distance of at least 100 μm from the first focal point. The adjustment of the distance to the first focus allows a flexible adjustment of the near-field sensitivity of the optical device, and said values ​​have proven to be a good compromise in practice.

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In further advantageous embodiments, the diameter of the diaphragm is 50-100%, preferably 80-100%, particularly preferably substantially 100%, of an image size B which is equal to GR * d1 / f1, where GR is the beam diameter of an emitted light beam in a predetermined Distance, d1 is the distance of the diaphragm to the first focal point and f1 is the distance of the primary lens to the first focal point.

Thus, the proportion of blocked near-reflected light beams and thus the attenuation of the near-field sensitivity of the device can be preset. For example, if the diameter of the aperture is 100% of the image size, the total reflection of a nearby object will be blocked, and less than 100% will block only a fraction.

In order to achieve the distance required between the first focal point and the detector unit for the diaphragm, two different configurations can be selected.

In a first embodiment of the invention, the optical device comprises a relay optics, which is arranged between the first focal point and the detector unit and adapted to focus the diverging from the first focus from the long-term reflected light beam to a second focus, wherein the detector unit substantially in second focal point is arranged. In this embodiment, conventional detectors can be used, whereby the cost of the optical device can be kept low. The relay optics can be used in addition to who / 41 to order special optical filters such as an interference filter in the area between the lenses of the relay optics.

In order to facilitate the assembly of the diaphragm, in this embodiment, the diaphragm can be mounted on the relay optics, which is particularly simple in the aforementioned conical shape, since the cone or truncated cone has a sufficiently large base surface for mounting. However, an assembly of the relay optics nearest aperture on the relay optics is advantageous even with disc-shaped aperture. Regardless of the aperture shape, the bezel can be glued to the relay optics, for example.

In the embodiment with relay optics, a plurality of relay optics can be used in cascade, which brings advantages in the construction of the optical device with itself when the installation of multiple panels turns out to be difficult in a row. To realize this, the optical device comprises a first and a second relay optics, which are arranged between the first focal point and the detector unit, wherein the first relay optic is designed to to focus the diverging long-range reflected light beam from the first focus to a second focus, and the second relay optic is configured to to focus on the second focal point diverging long-range reflected light beam to a third focal point, / 41 wherein said aperture is disposed between the first focal point and the first relay optic and said further aperture is between the second focal point and the second relay optic, and wherein the detector unit is disposed substantially at the third focal point.

In a second embodiment of the invention, the detector unit is disposed in the region where the far-aiming reflected light beam diverges from the first focal point, the detector unit having a detection surface extending over the entire cross-section of the far-end reflected light beam. In this embodiment can be dispensed with a relay optics, but for the detector unit, a larger detection area is required than in the first embodiment. Although large-area detector units are more expensive, the length of the optical device can be reduced.

In order to minimize the required detection area, the aperture can be mounted on the detector unit. Since the diaphragm is arranged at a predetermined distance from the first focal point, the detector surface can be kept smaller by mounting the detector unit on the diaphragm. In addition, the assembly of the aperture is simplified.

Preferably, the distance of the diaphragm from the first focal point and / or the surface of the diaphragm in said cross-section and / or the position of the surface of the diaphragm in genann11 / 41 th cross section is variable. This allows calibration and custom configuration of the bezel, allowing a single optical device to be adapted to different applications and applications.

For this purpose, the optical device moreover preferably also comprises a motor, which is designed to change the said distance and / or the said surface and / or the position of the surface of the diaphragm in the said cross-section. This allows automatic calibration or configuration of the aperture even during operation of the laser scanner. This is eg Particularly favorable when the optical device is used in a laser scanner, which is inaccessible during operation, for example in an unmanned aerial vehicle (UAV).

The invention will be explained in more detail with reference to embodiments illustrated in the accompanying drawings. In the drawings show:

1 is a schematic side view of an optical device for laser removal measurement according to the prior art;

FIG. 2 is a graph of the distance-dependent relative receive power of the device of FIG. 1; FIG.

3 is a schematic side view of a first embodiment of an optical device according to the invention for measuring laser distance with a window screen;

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FIG. 4 is a graph of the distance-dependent relative receive power of the device of FIG. 3; FIG.

5 shows a second embodiment of the optical device for laser distance measurement according to the invention with two disk apertures in a schematic side view;

Fig. 6 is a graph of the distance-dependent relative reception power of the apparatus of Fig. 5;

7 shows a third embodiment of the optical device for laser distance measurement according to the invention with a conical diaphragm in a schematic side view;

Fig. 8 is a graph of the distance dependent relative receive power of the device of Fig. 7;

9 shows a fourth embodiment of the optical device for laser distance measurement according to the invention with an oblique conical diaphragm in a schematic side view;

10 is a schematic side view of a fifth embodiment of the laser distance measuring optical device according to the invention with a pane diaphragm and an offset light source;

11 shows a sixth embodiment of the laser distance measuring optical device according to the invention with cascaded relay optics; and

12 shows a seventh embodiment of the optical device for laser distance measurement according to the invention with a large-area detector unit.

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Fig. 1 shows an optical device 1 according to the prior art. In this optical device 1, which is typically used in laser distance measurement, a light source 3 located centrally in front of a primary lens 2 emits a light beam 4.

The light source 3 in the present embodiment is a mirror that emits light provided by another unit, eg, laser light, in a predetermined direction R1 that is substantially parallel to the optical axis A of the primary lens 2. Alternatively, the light source 2 may be directly a light-generating laser diode, lamp or the like.

When the emitted light beam 4 is reflected by a remote target (not shown), the far-reflected light beam 5 always falls substantially in the direction opposite to the emission direction R1 direction R2 parallel to the optical axis A on the primary lens 2, which by the in relation to the size of the Primary lens 2 wide distance between the long-term objective and primary lens 2 is conditional.

The primary lens 2 is designed in such a way, for example by selecting a corresponding radius of curvature, that it focuses the long-range reflected light beam 5 in a first focus F1. For this purpose, the primary lens 2 may be formed, for example, as a convex lens 2 or other optical element capable of condensing incident light rays.

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For detection of the long-range reflected light beam 5, there is a detector 6 in the first focal point F._x, The detector 6 is, for example, an avalanche photodiode ("avalanche photodiode", APD), which is used as a highly sensitive photodiode and thus can detect the long-range reflected light beam 5 even at low light output.

Fig. 1 further shows a near-reflected light beam 7 which has been reflected by an undesired near target, eg an air impurity, an insect or the like. The near-reflected light beam 7 is incident obliquely to the optical axis A on the primary lens 2, which is due to the small in relation to the size of the primary lens 2 distance between near target and primary lens 2.

Under near-reflected light beams 7 are understood to mean those light beams emitted by the light source 4 and reflected by a near target at a distance of preferably less than 500 m, more preferably less than 100 m, most preferably less than 30 m Primary lens 2 is located. By contrast, by far-reflected light beams 5 are understood to mean those light beams emitted by the light source 4 and reflected by remote targets outside these distances.

Due to the oblique direction of incidence of the near-target reflected light beam 7 on the primary lens 2, this is usually not on the focal point F_x focused. Depending on the angle of incidence and incident position on the primary lens 2, however, the light beam 7 which is reflected near the target is projected onto the detector 6, which registers its presence and thus outputs a "false" measurement result, ie not correlated with the remote target to be detected.

FIG. 2 shows an amplitude characteristic 8 typical for the optical device 1, the ordinate representing the relative reception power registered by the detector 6 in [dB] and the abscissa the target distance in [m]. It can be seen that the receiving sensitivity of the device 1 has a maximum precisely in that close range of about 5 m, in which measurement results of interfering near targets are undesirable.

FIG. 3 shows a first embodiment of an optical device 9 according to the invention, wherein reference numerals used with respect to FIG. 1 stand for identical components. In particular, the angular proportions of the emitted, near-end reflected and near-end reflected light beams 4, 5, 7 are the same, but the detector 6 assumes a different position, as will be explained below.

In the embodiment of FIG. 3, a relay optic 10 is arranged such that the first focal point F₁ between the primary lens 2 and the relay optics 10, ie the relay optics 10 is arranged in the direction R2 of the long-range reflected light beam 5 behind the first focus F1.

The relay optics 10 is adapted to the diverging from the first focus F1 from distant-reflected light / 41 beam 5 to a second focal point F₂ in which the detector 6 is located in the optical device 9. The relay optics 10 may be formed, for example, as a convex lens, as two composite convex lenses 11 as shown in FIG. 3, or as two plano-convex lenses 12 as shown in FIG. If a relay optics 10 with two lenses 11, 12 is used, in addition a filter, for example an interference filter, can be inserted between the two lenses 11, 12.

In order to block near-reflected light beams 7, a diaphragm 13 is within a normal to the optical axis A cross-section Q.₁ of the long-range reflected light beam 5 is disposed between the first focal point F1 and the relay optical system 10. The diaphragm 13 is opaque and preferably has no holes.

As shown in FIG. 3, the light source 3 is arranged centrally in front of the primary lens 2 in the beam path, as is customary in laser measuring technology in the beam direction of the light beam 5 reflected by the long distance. As the beam path of the long-range reflected light beam 5 is herein understood that area which is traversed by the long-range reflected light beam 5.

Due to the fact that the light source 3 is arranged in front of the primary lens 2 in the beam path, the light source 3 casts a shadow S in the light beam 5 reflected by the aiming beam. Already by the arrangement of the light source 3 in front of the Primärlin / 41 se 2 and the shadow caused thereby S thus a reduction of the receivable by the detector 6 amount of fernzielreflektiertem light is conditional. In order not to impair the performance of the optical device 9 for detecting the long-distance reflected light, the diaphragm 13 is located in said shadow S of the light source 3.

The diaphragm 13 is in the embodiment of FIG. 3 a disc, ie it has seen a small thickness in the beam direction R2 of the long-range reflected light beam 5. The shape of the disk in cross section Q1 can be arbitrary, eg rectangular, circular or oval, or even to the shape of the shadow S of the light source 3 and thus adapted to this itself. If the light source 3, for example, casts a round shadow S in the cross section Q1, then the shape of the diaphragm 13 in the cross section Q1 can also be round.

The area x1 of the diaphragm 13 in the cross section Q1 is, for example, 0.1-50%, preferably 0.5-25%, particularly preferably 1-10%, of said cross section Q1 of the long-range reflected light beam 5 and can in principle be selected independently of the shadow S. , Alternatively, the area x1 of the diaphragm 13 in cross section Q1 can be adapted to the shadow S cast by the light source 3, for example such that the diaphragm 13 completely occupies the shadow S in the cross section Q1. Alternatively, the area x1 of the diaphragm 3 in the cross-section Q1 may also be in a predetermined relationship to the shadow S and occupy, for example, 50% of the shadow S.

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In a further embodiment, the diameter of the diaphragm 13 can also be adapted to the size of the cross-section Q1 image of that focal spot, which results in an extended near target at a predetermined distance R from the primary lens 2 when the beam diameter and the beam spread of the emitted light beam 4 over the distance R are taken into account.

In order to completely blank out the reflection of a near target located at the distance R, the diameter of the diaphragm 13 corresponds to at least one image size B with

B = Gr * d1 / f1, where GR is the beam diameter of the emitted light beam 4 at the predetermined distance R, d1 is the distance of the diaphragm 13 to the first focus F1, and f1 is the distance of the primary lens 2 to the first focus F1. This results from the lens equation for a thin primary lens 2. The diameter of the diaphragm 13 may also be 50-100% or 80-100% of the aforesaid image size B to block only a predetermined amount of near-target reflected light.

If the panel 13 is realized as a disk, this can for example be a plate supported by webs and so be introduced between the primary lens 2 and the relay optics 10. Alternatively, the shutter 13 may be an opaque structure carried by a glass plate, which is etched into the glass plate, for example, or adhered thereto.

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The aperture 13 has the purpose of blocking near-end reflected light beams 7, as shown in FIG. 3 is shown. Nahzieleflektierte light beams 7 cross the optical axis A usually between the first focus F1 and the relay optics 10 so that they meet the shutter 13 and are blocked. As described above, since the diaphragm 13 is arranged in the shadow S of the light source 3, the light beams 5 which are reflected away from the long distance are not affected by this arrangement of the diaphragm 13.

Fig. 4 shows the effect of the diaphragm 13 in detail. Analogous to FIG. 2, the ordinate in FIG. 4 plots the relative reception power in [dB] and the abscissa plots the target distance in [m]. For reference, the typical amplitude curve 8 of the optical device 1 according to the prior art of FIG. 1 is also shown in FIG. 4.

The amplitude curve 14 shows the reception sensitivity of the optical device 9 of FIG. 3 with the diaphragm 13 between the first focal point F₁ and the relay optics 6. The diaphragm 13 is at a distance d1 (FIG. 3) from the first focal point F₁ arranged. At this distance d₁ are refracted by the primary lens 2, for example, light beams 5, which are reflected by near targets, which are at a distance of 8 m in front of the primary lens 2. This causes a minimum M₁of the amplitude curve 14 for the target distance of 8 m. The shape and relative depth of the minimum M1 is determined by the shape and size of the surface x₁ the aperture 13 in cross-section Q₁ dependent / 41 and can be determined experimentally by experiments or by simulations.

FIG. 5 shows a variant of the optical device 9 of FIG. 3, in which, in addition to the diaphragm 13, a further diaphragm 15 is arranged between another optical axis A normal cross-section Q2 of the remote-controlled light beam 5 between the first focal point F1 and the relay optics 10 is arranged. The further diaphragm 15 is arranged at a distance d2 from the first focal point F1, wherein the distances d1 and d2 are different.

The further diaphragm 15 may be formed structurally exactly the same as the diaphragm 13, for example in each case as a disk, and also as the diaphragm 13 may be made, for example as a plate with webs or as a supported by a glass plate opaque structure. The aperture 13 and the further aperture 15 can also

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Aperture 15 may be the same size in the respective cross section Q1, Q2. Alternatively, as shown in FIG. 5, the diaphragms have different areas x1, x2 in cross-section, their area x1, x2 being greater the closer the respective aperture 13, 15 is to the relay optics 10. The size of the respective surface x1, x2 preferably follows the beam path of the light beam 5 reflected by the distance between the first / 41

Focal point F₁ and the relay optics 10, so that the relationship between distance d₁, d₂ and area x₁, x₂ in cross-section Q₁, Q₂is constant, ie d₁/ x₁ = d₂/ x₂,

The first focus F₁ nearest aperture 13 is at a distance of at least 100 microns from the first focal point F₁ arranged to ensure that the long-range reflected light beam 5 is not blocked by the diaphragm 13. This also applies to the embodiment of FIG. 3.

FIG. 6 shows, analogously to FIGS. 2 and 4, the relative received power in [dB] on the ordinate and the target distance in [m] on the abscissa, wherein in addition to the amplitude curve 16 of the optical device 9 of FIG for reference, the amplitude curve 8 of the optical device 1 of Fig. 1 is shown.

In the example of FIGS. 5 and 6, the distance d₁ the aperture 13 is selected such that it corresponds to a target distance of 5 m, and the distance d₂ such that it corresponds to a target distance of 15 m. This causes two minima M₂, M₃ the amplitude curve 16 for the target distances of 5 m and 15 m.

Fig. 7 shows a further variant of the optical device 9 of Fig. 3, in which instead of a disc-shaped aperture 13, a diaphragm 17 is arranged in a truncated cone shape between the first focal point F1 and the relay optics 10. The shape of the aperture 15 expands here in the beam direction R.₂ seen the long-distance reflected light beam 5 and could also / 41 be formed as a cone shape. Alternatively, instead of the conical or truncated cone shape, a non-expanding rod shape could also be used.

The opening angle (cone tip angle) of the conical or truncated cone shape of the aperture 17 can basically be chosen arbitrarily. In the exemplary embodiment of FIG. 7, the opening angle has been adapted to the beam path of the light beam 5 reflected by the distance.

The conical aperture 17 of FIG. 7 is thus arranged not only within a cross section, but equally within a continuum of cross sections Qi of the long-range reflected light beam 5 between the first focus F1 and the relay optic 10. In this sense, the diaphragm 17 may be defined in a conical or truncated conical shape by being disposed within a cross section Qi between a first cross section Q1 at a distance d1 from the first focal point F1 and a final cross section Q2 at a distance d2 from the first focal point F1 ,

The first cross-section Q1 does not coincide with the first focus F1, but is spaced therefrom by a minimum distance d1 to ensure that the long-range reflected light beam 5 is not blocked by the stop 17. The first cross section Q1 is, for example, at a distance d₁ of 100 μm from the first focal point F₁,

The embodiment of FIG. 7 with respect to FIG. 3 and 5 variants explained no restrictions and terworfen. Thus, for example, two diaphragms 17 may be used in the form of cones or truncated cones, which may be mounted by means of webs or formed as opaque structures carried by (thick) glass plates. If the aperture 17 is formed as a cone or truncated cone, it is advisable to mount the aperture 17 on the relay optics 10. For this purpose, for example, the base of the cone or truncated cone of the diaphragm 17 are glued to the relay optics 10, which can preferably be formed flat on the side of the aperture 17.

In the same way but also the relay optics 10 closest discoid aperture 13, 15 of Fig. 3 and 5 could be mounted directly on the relay optics 10, for example by gluing.

8 shows, analogously to FIGS. 2, 4 and 6, the amplitude curve 18 of the optical device 9 of FIG. 7, wherein the relative received power in [dB] is plotted on the ordinate and the target distance in [m] on the abscissa is and for reference the amplitude curve 8 of the optical device 1 of Fig. 1 is shown.

It can be seen from the amplitude curve 18 that, in contrast to the amplitude curves 14 and 16 of FIGS. 2 and 4, the conical or truncated conical aperture 17 of FIG. 9 no longer forms discrete minima, but rather a substantially continuous minimum at the height of -90 dB.

FIGS. 9 and 10 show further embodiments according to which the light source 3 is decentralized in front of the primary lens 2 (FIG.

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9) or not at all in front of the primary lens 2 (FIG. 10).

From Fig. 9 It can be seen that a light source 2 arranged asymmetrically with respect to the optical axis A throws an asymmetrical shadow S. If an aperture 19 is arranged here in the shadow S of the light source 3, its shape is correspondingly adapted to the shadow S. For this purpose, a diaphragm 19 can be used, as the asymmetrically arranged about the optical axis A oval disc or slate cone or slate truncated cone, as shown in Fig. 9 shown, is formed. In such embodiments, the receiving sensitivity of the device 9 for long-range reflected light beams 5 is not affected by the diaphragm 19 when it is arranged in the shadow S. However, the shutter 19 blocks at least a proportion of near-end reflected light beams 7, so that the near-field sensitivity of the optical device 9 is reduced.

FIG. 10 shows an embodiment in which the light source 3 is arranged next to the primary lens 2 and not in front of it. Due to the offset of the light source 3 with respect to the primary axis A, light rays reflected by the target do not fall parallel to the optical axis A. To compensate for this effect, the aperture 13 may be eccentrically positioned with respect to the primary lens 2 to block a greater proportion of near-end reflected light beams 7, as shown schematically in FIG. 10 shown.

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It is immediately apparent that no shadow S is thrown through the light source 3 in this embodiment. However, if the aperture is the same as in Fig. 3 Surprisingly, apart from the above-explained effect of the off-center incident near-target-reflected light beams 7, substantially the same amplitude curve 14 as in the embodiments of FIGS. 3 and 4, in which the diaphragm 13 completely occupied the shadow S in the cross-section Q1. This is due to the fact that the light beams 5 reflected by the long-distance are not blocked by the light source 3, but by the diaphragm 13 this time.

Instead of the disc shape of the diaphragm 13 of FIG. 10, any other diaphragm shape as described previously for FIGS. 3 to 9 can again be used, and the same amplitude characteristics are achieved as if the diaphragm were arranged in the shadow of the light source 3.

11 shows an embodiment in which a plurality of relay optics 10, 20 are arranged in cascade, so that a separate diaphragm 13, 15 can be provided for each relay optics 10, 20.

In this embodiment, the first relay optics 10 focuses the far-aiming reflected light beam 5 diverging from the first focus F1 to a second focus F2, and the second relay optics 20 focuses the far-aiming reflected light beam 5 diverging from the second focus F2 to a third focus F3 Detector / 41 unit 6 substantially in the third focal point F₃ is arranged, resulting in the cascade arrangement.

The diaphragms are here arranged such that said aperture 13 between the first focus F1 and the first relay optics 10 and said further aperture 15 between the second focus F₂ and the second relay optics 20 is arranged. The distances d₁, d₂ The apertures 13, 15 of the respective nearest focal points F1, F2 can be selected such that the apertures 13, 15 suppress near-target-reflected light beams 7 from different target distances in front of the primary lens 2.

In all embodiments, disc, cone or truncated cone diaphragms can be used. However, disk apertures are preferably used and the diameter of the apertures can be made dependent on the respective distance d1, d2 of the aperture 13, 15 to the respective nearest focal point F1, F2.

It is understood that the cascade form shown can also be extended by more than two relay optics, each with a diaphragm 13 are used instead of two relay optics 10, 20, each with a diaphragm 13, 15. In addition, it is possible to use more than one aperture for at least one of the relay optics 10, 20.

The various relay optics 10, 20 may be the same or different, for example, one with convex / 41 xen lenses as in Fig. 3 and the other / n with plano-convex as in Fig. 7, and / or with different focal lengths ,

FIG. 12 shows a variant of the optical device 1 of FIG. 3, in which no relay optics 10 is used. Instead, the detector unit 6 is placed in the area in which the long-range reflected light beam 5 diverges from the first focal point F1, the detector unit 6 having a detection area extending over the entire cross section of the long-range reflected light beam 5 and thus having a larger detection area than the detection area Detector unit 6 of the embodiment of FIG. Third

When the diaphragm 13 is mounted directly on the detector unit 6, the distance between the first focal point F1 and the detector unit 6 can be reduced substantially to the distance d1 between the first focal point F1 and the diaphragm 13. In principle, however, the detector unit 6 can also be spaced apart from the diaphragm 13. The embodiment of FIG. 11 with a large-area detector unit is generally suitable for apertures 13 with cone or Truncated cone shape as shown in Figs. 7 and 9.

In all these embodiments, in addition, the distance d1 of the aperture 13, 15, 17, 19 from the first focus F1 and / or the surface x1, x2 of the aperture 13, 15, 17, 19 in said cross-section Q1, Q2 and / or the position the surface x1, x2 of the aperture 13, 15, 17, 19 in said cross-section Q1, Q2 be changeable, for example by the aperture 13, 15, 17, 19/41 along the optical axis A - or normal to this - arranged manually displaceable is.

If a pane is used, this can for example be composed of a plurality of crescent-shaped lamellae, which increase or reduce the area of ​​the pane aperture by a rotational movement.

Cone or truncated cone apertures can be designed with a variable opening angle, or alternatively telescopic rods can be used, whereby, depending on the telescoping state, the area of ​​the aperture in the respective cross section Qi also changes.

Instead of manually, the aperture 13, 15, 17, 19 can also be moved by a motor which changes the said distance d1, d2, the said area x1, x2 or the said position.

In all of the aforementioned embodiments, the diaphragm 13, 15, 17, 19 leave the outer edge of the cross section Qi free, so that the entire surface x1 of the diaphragm 13, 15, 17, 19 lies within said cross section Qi. The aperture 13, 15, 17, 19 can be arranged at a predetermined minimum distance from the outline of the cross section Qi. Alternatively, the aperture 13, 15, 17, 19 also project laterally from the outside into the cross section Qi. In these variants, the diaphragm 13, 15, 17, 19 leaves at least 50%, preferably at least 70%, particularly preferably at least 90%, of the outline of the cross-section Qi free. The aperture 13, 15, 17, 19 may further be arranged hole-free / 41 and / or such that it intersects the optical axis A.

Generally speaking, the aperture 13, 15, 17, 19 is arranged and / or formed such that it blocks a larger proportion of light beams 7 reflected near the target than light beams 5 reflected by the long range.

The invention is therefore not limited to the illustrated embodiments, but includes all variants, modifications and combinations thereof that fall within the scope of the appended claims.

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