DE2809812A1 - PASSIVE OPTICAL DISTANCE RANGE SIMULATOR - Google Patents

Description

Passive optical range simulator

The invention relates to a passive optical range simulator with an adapter for mechanical coupling to an optical radar system, which a light beam predetermined Emits frequency and receives reflected light radiation and, if necessary, extraneous light radiation.

The modern electro-optical weapon technology requires very fine and sophisticated Test methods to ensure the accuracy of measurements. In particular, it is important to use technical facilities precise distance relationships for optical radars, an exact adjustment of all optical channels and the functioning of circulation systems or by systems with a back and forth light beam. To achieve this are simply structured and easy-to-use test facilities are very desirable.

So far, the operation of such systems has primarily been done with the help of

two procedures checked:

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FLEUCH AUS & WEHSER

_{Our sign} WS116P-1745

1. By measuring a measuring field in the open air, in which Targets with certain characteristics are arranged;

2. through the use of active optical transponders that are directly linked to the system to be examined.

In the first case, there is a very large area in the form of a measurement site required, which creates both difficulties in terms of weather conditions influences as well as because of the necessary security. In the second case, a critical optical boundary layer or interface, in particular required with respect to the adjustment axis and furthermore it is difficult for the transponder to simulate echoes in such a way that they contain the identifier have a real goal. The amplitude of the returning signals must be known when contributing to the receiver sensitivity to determine the overall functioning of the system. These amplitudes are not easy to get at the wavelength of interest calibrate or adjust, especially if short pulses and signal levels are used that are very close to the threshold values the optical receiver. The time allocation of the response signals is also very critical for the range accuracy or the distance accuracy and it is not easy to get the desired accuracy to achieve and maintain with relatively cheap radiation sources.

It is an object of the invention to provide a passive optical range simulator or distance simulator to create with which the above-mentioned difficulties can be overcome and which in a simple manner the checking and adjustment of optical radar systems or laser systems.

These

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According to the invention, this object is achieved in that the simulator an entry opening is provided through which the light beam into the Simulator enters and through which the reflected light radiation and optionally the extraneous light radiation leaves the simulator that in the A focusing device is connected to the light path, which has a focal point in a common plane with the entrance surface of an optical delay line has a light-conducting fiber or a fiber bundle, and that at the other end opposite the common plane a reflector is arranged on the optical delay line.

Further refinements of the invention are the subject matter of further ones Claims.

There is no need according to the measures of the invention for a collimator arrangement at the optical boundary layer to the optical system to be checked. The distance range simulator or Distance simulator can be connected directly to the system to be checked using of the adapter. This significantly simplifies optical alignment and eliminates the risk of vignetting. the Focusing device or the focusing lens has a very large opening to direct the bundle of rays onto the entrance surface of the Focus on conductive fiber.

By using the consisting of an inclined glass plate primary attenuator, an open-air characteristic for the radiation beam is simulated by the reflection of energy back into the system under investigation from the first reflective surface is avoided. With flat glass elements inclined towards each other an attenuator is created that prevents an undesired shift of the light beam or the beam when passing through

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FLEUCHAUS & WEHSER

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running this attenuator avoids. The one used as a delay line used optical fiber is wound on a spool, and is in capable of reflecting devices provided on the end faces of the fiber to cause multiple reflections within the fiber from one end to the other. For the light-guiding fiber, it is expedient a multimode fiber is provided, either as a step index fiber or can be constructed as a gradient fiber. This fiber is provided with a mechanical buffer through the sheathing to prevent losses to be kept as low as possible in the fiber due to mechanical influences. At the front end there is a partially reflective one on the entry surface Mirror provided so that the light beam with the wavelength of interest can get into the fiber and experience a partial reflection there, so that part of the energy can be decoupled again and thereby a series of simulated target echoes are created, which at equal intervals, d. H. distance ranges simulated by a multiple of the length of the delay line are available.

The advantages and features of the invention also emerge from the following description of exemplary embodiments in conjunction with the claims and the drawing. Show it:

1 is a schematic representation of a passive optical range simulator according to the invention;

2 shows a partial section of a modification of the measuring range simulator 1 using a partial mirror on the entry side of a fiber optic delay line with otherwise the same Construction.

In the embodiments of the invention shown in the drawing the passive optical measuring range simulator includes an adapter 1 for attaching the simulator to a corresponding counterpart of the optical radar system 2 to be checked. The adapter 1 is

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with

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provided with holes 3 into which at the front end of a housing 5 Position pins 4 arranged in the measuring range simulator can be used. The adapter is designed such that it has a congruent and / or coaxial alignment of the inlet opening 6 of the measuring range simulator with the outlet opening 7 of the optical radar system for checking enables. If the system to be checked has a characteristic construction deviating from the illustration, the adapter will be used accordingly adapted so that a quick replacement is possible in the case of repeated checks of similar systems. Through the exit opening 7 of the optical radar system, laser pulses emerge along the adjustment axis 8, which re-enter the axis along parallel edge axes 9 or 10 System can be returned through the opening 7. Along the rest parallel edge axes of the system, the optical information is received by a television camera, not shown. With attached to adapter 1 Clamping screws 11, the position pins 4 are locked in the holes 3. Further fastening devices, not shown, can be used be provided in order to connect the adapter 1 to the optical radar system 2 to be checked. With the help of the tensioning screws 11 and the Position pins 4 can the housing 5 of the measuring range simulator in such a way mounted so that vignetting is avoided.

All rays from and to the system to be checked, which run along the adjustment axis and the parallel edge axes of the system, are in a weakening member 12, which is arranged, for example, at 45, attenuated, with a surface reflection in the exiting beam is conducted downward on the attenuator into a radiation absorber, which consists of a second radiation absorber parallel to the attenuator 12 arranged absorber plate 14 and two black surfaces 15 and 16, which reflected on the absorber plate 14 or through absorb these residual radiation passing through. This first one

Weakening

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Patent attorneys

ORHGQ 1 ")

Un.erZeich.n: WS116P-1745

The attenuation element at the input of the measuring range simulator is intended to ensure that this has the properties of a free space for the system to be measured and reduces the reflected energy to a minimum, which could otherwise trigger an overdrive of the receiving part for the reflected radiation, which may also lead to destruction of the laser source.

The beam path runs through a focusing lens 17, which consists of the parallel beam makes a converging beam, the focal point of the radiation at the front end 18 of a light-guiding Fiber 20 or a fiber bundle, which is wound to form a spool 19 and provided with a mirror 21 at the rear end 22 is. The focusing lens 17 must have a good optical quality so that the blurring ring at the wavelength used and of interest is small enough to ensure efficient coupling to the front end 18 of the fiber bundle 20. Furthermore, the focusing lens be free of a chromatic apparatus for the wavelengths of the optical radiation used, e.g. emanating from the laser pulse for area scanning and a visual bundle of rays when observing with the television camera. One light frequency for one case and a nominal frequency for the other case are sufficient for practical purposes in most cases. The focal length of the focusing lens 17 is selected in such a way that a good match with the numerical aperture of the fiber bundle 20 results and there is a sufficiently small diffraction-limited focus at the front end 18 of the fiber bundle for efficient coupling. In terms of In terms of the focal length, a compromise must often be made between these two requirements. So for a given laser beam divergence the transmitter's focus can be reduced to improve coupling by using a short focal length finds, whereby a larger refraction for the numerical opening of the available fiber bundle for the input coupling is used

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Patent Attorneys 280981?

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and accordingly less for the output coupling to the receiver input of the system is available. As a compromise for the focal length, a length of about 27 cm was chosen for one version.

An attenuator 24 for fine tuning is in the beam path arranged between the focusing lens 17 and the front end 18 of the beam. This attenuator consists of two against each other inclined glass plates 25 and 26, which serve as damping elements, through which the focused bundle of rays to the plane of entry of the fiber bundle runs. The inclined position of the attenuators prevents that the surface reflections are transmitted back into the optical radar system. The alignment of the inclined glass plates takes place in such a way that the adjustment axis is retained, i.e. the conditional diffraction of the beam is compensated for again. the Adjustment can be set by exchanging and replacing similar damping elements with different absorption values.

The entry surface or the front end 18 of the fiber bundle is polished and embedded in an end piece, which consists of a short polystyrene tube 30, in which the glass fiber bundle or the glass fiber 20 is centered is held with the help of epoxy resin 31. This end piece is held in an adjusting element 32 which, with the aid of adjusting screws 33, 34 and 35 a positioning of the entry surface of the fiber bundle in the allows three mutually perpendicular coordinate axes X, Y and Z. A compression spring is located between the adjusting element 32 and the housing 5 36 inserted, which are more or less compressed under the influence of the adjusting screw 34 when moving the adjusting element will. The actual guide elements for the adjustment element are not shown. With the help of the adjustment in the X-Y-axis, the entry surface 18 of the fiber bundle in coincidence with the common focal point ^

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Patent attorneys

Our reference: WSl IGP-1745

point of the bundle of rays from the axis ray 8 and the marginal rays 9 and 10 are brought, with the help of the adjustment in the direction of the Z-axis fine focusing is possible. The coiled light-conducting Fiber 20 or the bundle of rays is typically between half a kilometer and one kilometer long and is in the form of a spool 40 housed a plurality of nested layers, the resulting stress is taken into account in order to keep the stress on the fibers and the optical losses to a minimum. The fiber optic can e.g. consist of a low-loss fiber, such as that supplied by Corning Glass Works, which typically results in losses on the order of 2.5 db / km at a wavelength of 1064 nm result. The core diameter and the clothing diameter are about 85 .mu.m and 125 .mu.m. The numerical opening lies in one Range from about 0.14 to 0.18, with a typical pulse spread of about 10 nsec / km. This fiber is mechanically in Protected their entire length with an elastic urethane cover, which has a nominal thickness of about 0.12 mm, so that overall gives a thickness for the glass fiber of about 0.38 mm.

The rear reflective end of the fiber optic is practically identical to that the front end is formed, but with the polished end face at a distance of about 0.25. 10 mm from the surface of the flat Mirror 21 is arranged. To maintain the distance, an intermediate piece (not shown) is used, with an adjustment of the rear End of the fiberglass is not required. The mirror 21 is preferably designed in such a way that it has a reflection of 99.9% at the point of interest Wavelength in connection with a high transmittance at the wavelengths of visible light. This enables the reflection of the laser beam pulses with low losses and at the same time the coupling of light through the mirror from a light source mounted behind the mirror 41 for visible light. The attenuators or damping

limbs 12

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members 12, 25 and 26 are designed so that they are of interest Absorb wavelength essentially and are relatively transparent to the wavelength of visible light. This makes it possible to use the light source 41 of light to be coupled into the glass fiber, which on the television monitor of the system to be examined as the corresponding from the front entrance surface 18 emitted light can be seen. This makes the front end of the glass fiber almost visible as a point light source and on the one hand facilitates the adjustment of the front entry surface of the Glass fiber on the adjustment axis 8 and, on the other hand, a subsequent fine-tuning the focal length.

The optically passive measuring range simulator described so far is used the optical fiber as an optical delay line to a single To deliver an echo signal with which the distance calibration and the accuracy of the adjustment axis of an optical radar system are determined can be. Span calibration of the simulator can be performed using one of the following methods:

a) it becomes the length of the light-guiding fiber or the fiber bundle measured and this determined length converted into the effective optical length using the known refractive index for the fiber;

b) an optical radar system that has been found to be good is used to transferring the calibration with respect to an outdoor target acquisition to the simulator to be calibrated;

c) it becomes the speed of propagation of the optical pulses in a direction through the delay line out of the optical fiber to determine the effective length of the line.

In practical use, none of these processes proves to be simple or easy to carry out and the second method has usually been used for calibration up to now. The target echo due to a single

known

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known distance is sufficient to zero-span for the optical and radar system under test, provided that the range scaling of the system is accurate and linear behaves. Under these conditions, the calibration is also valid for other ranges and distances, although only for a single distance was measured. There are cases in which there is no certainty about the linearity of the system, even though the scaling factor is initially was determined or ascertained by an independent electrical measurement.

Because of this, it seems desirable to have several To simulate target echoes that are at different measuring distances in order to capture the entire area window of interest. It will a minimum of three such target echoes are required to distinguish between the effects of a zero range adjustment and an adjustment by range scaling to distinguish and to estimate the fundamental ability of the system to accurately measure distance intervals over time. The zero range of the system can be detected or adjusted by any target echo. The, if necessary, coordinated range scaling to ensure a correct Getting range reading can be set with a second target echo and finally the correct range reading can be done independently can be determined with the help of a third target echo.

There is also a need for a variety of target echoes in order to Practice dynamic response to a variety of targets and adjustment in range to a most distant target. It is desirable to have a simulator for a variety of targets, essentially through your own calibration, to confirm the high

Avoid costs in terms of time and inconvenience that associated with the three independent calibration procedures mentioned above. On the way to achieving the above properties

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It is important to have the ability to determine the adjustment axis accuracy preserved.

FIG. 2 shows a modification of the measuring range simulator according to FIG. 1 illustrated by using the foregoing objectives a partial mirror at the entrance surface 18 of the light-guiding fiber 20 can be reached, so that multiple reflections within the light-guiding Fibers are created by reflective surfaces at the ends of the coiled fiber. The partial mirror 37 is a boundary layer of a Entry window. 38, which is mounted in the adjusting element 32. The boundary layer is made partially reflective in that a dielectric layer is provided. The entrance window is covered with an anti-reflective coating on the outer surface. The direct one physical contact between the partially reflecting partial mirror or the boundary layer and the end face of the fiber causes low losses. The laser pulses introduced from the optical radar system 2 into the fiber end at the partial mirror 37 cause the latter to be transmitted Pulses through the fiber 20 including the part located on the spool 19 up to the mirror 21 at the other end 22 and back to the partial mirror at the entry end of the fiber. Each individual laser pulse runs between the partial mirror 37 and the mirror 21 at the end of the fiber over the wound Fiber back and forth several times. Every time the reflected laser pulse arrives at the partial mirror 37 and of sufficient Is amplitude, it can be observed via the receiver (not shown), e.g. along the parallel edge beams 9 and 10. Preferably the partial mirror 37 has a degree of reflection of 63% at the frequency of interest of the laser pulse.

Since part of the energy of the laser pulse is at the entry surface of the partial mirror with the wavelength of interest is reflected and another part is allowed to pass through, the

dined

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Patent attorneys

Our reference: WS 11 6P-1745

drew light energy gradually with each reflection, so that one Series of target echoes arises, which correspond to one at the same distance Multiples of the optical length of the delay power occur. The partial transmission properties of the surface of this partial mirror do not constitute an obstacle when coupling the laser pulses into the wound fiber from the transmitter of the optical radar system. For the requirement a maximum amplitude of the reflected pulses becomes a totally reflecting mirror at the other end of the fiber optic or the fiber bundle existing delay line required.

As in the embodiment according to FIG. 1, the parallel The bundle of rays is bundled by the focusing lens and combined in a focal point which, according to the adjustment, lies in the entrance surface of the light-guiding fiber. The reflective surface of the partial mirror also coincides with such a plane and stands in physical Contact connection with the front end of the glass fiber. Attaching the partial mirror to get the multiple reflection does not have one Influence on the focusing, since the central axis or the adjustment axis is retained. Both reflectors have a dielectric Layer in order to adapt them to the high energy densities generated by the optical radar system and to the desired Maintain properties at the wavelength of interest while maintaining transparency at visible wavelengths. This will divert the visible light from the one at the other end Light source transmitted through the optical fiber to illuminate the entrance surface and to facilitate the positioning of the focal plane.

A change in the number of target echo reflections that can be achieved results either through a change in the light attenuation in the optical path outside the reflection line, namely through a tunable one

Attenuator

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Attenuator or through a targeted separation of the rear end or the exit ends of the optical fiber from the reflective mirror.

Of these two possibilities, the first is preferred when it is desired to change the damping in discrete calibrated steps is, whereas the second measure to a continuous damping adjustment leads. In both cases, less recognizable target echoes are generated by increasing the light path attenuation. The number the realizable target echoes is a function of the usable dynamic range of the simulator, which is the rest of the dynamic range of the overall system after all losses have been subtracted. The useful dynamic range is usually limited Input power because of the need to avoid damaging the optical surfaces, e.g. the entrance reflector and the attenuation introduced into the radiation path to limit the focused energy density is a very substantial part of those mentioned Represent losses. Therefore, a typical test system can have a dynamic range of over 130 db, of which about 50 db are available in the simulator in a usable form. A theoretical model was developed, which the predicts the useful dynamic range required for the visibility of the nth target echo, if it is related to the influences of the Momentum spread is corrected. For a delay line of 0.5 km, with the losses at the wavelength of interest 2.5 db / km and using an entrance mirror with a reflection of 63% and a total reflecting end mirror the following values:

Tabel

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Our sign:

WS117P-1745

Order η of the target echoes Requirement for usable dynamic range in db

1 16.5

2 24.2

3 31.1

4 37.7

5 44.0

From this listing you can see that 50 db for the usable dynamic range should generate five target echoes, the amplitudes corresponding to the difference in db from the value of the The amplitudes decrease at the first echo η = 1. On this basis you can five target echoes simulate areas up to about 3 700 m in air, with a comparatively short and therefore very inexpensive delay line from a light-guiding fiber is required and in a linear relationship five interposed 'equal distances are determined.

The target echoes inserted at equal intervals can also be used for this be used to calibrate both the length of the delay line as well as the system range, if the system under investigation includes an exact range gradation. That Accuracy criterion is met if reference time intervals are supplied by a precise time or frequency source if the temporal range intervals can be achieved in a linear manner and if the correct factor for the read range gradation with With the help of electrical measures.

A good linearity with regard to the time range intervals is achieved by the quality of the spacing of the target echoes and is characterized by the

Scale

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. ' _u , " _z ,"",: WS117P-1745

Scale factor or the zero setting filer not influenced, d. H. the "Visible area" of each target echo is sufficient to determine the equality of the distances. In these circumstances the is readable Area corresponding to the spacing of the echoes, a measure of the effective length of the delay line from the optical fiber, i.e. the delay line is precisely calibrated within the range. Slight random deviations from exactly the same distances can occur in practice due to corresponding deviations in the linearity over time for the range intervals. The influence of these errors can be caused by the Calculation of the mean distances can be minimized if the mean distances are assumed to be equal to the subdivision of areas from the first to the nth target echo divided by (n-l). The accuracy increases with increasing η. Once the length of the coiled Detecting the delay line from the optical fiber can determine the accuracy of the zeroing of the system will. It is evident that any noticeable deviation of an exact multiple between the first echo region and the following Echo ranges indicates a zero range adjustment error. The amplitude and the direction of this error is determined from the the following equation, which describes the true distance of the nth target echo.

is in it

η = an integer greater than 1

R = the true distance of the nth echo
η

R = the apparent distance of the nth echo η

R ₁ = the apparent distance of the first echo.

The size

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Patent attorneys 2 R P Q S 1 9

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The size in square brackets indicates the amplitude and the sign the zero adjustment error. This information can be used to correct the zeroing of the system. Once this has taken place, the displayed and the calculated or true overlap Areas or distances. This calibrates both the system under test and the optical delay line. One can see that the ability delivering a multitude of target echoes is essential for calibration is, although the basic reference value for the calibration is the precise time or frequency source in the system to be examined.

Because of the additional propagation distance within the fiber shows each target echo has a greater broadening than the previous one. By selecting a specific target echo, this behavior can lead to Simulate the amount of pulse broadening which can be used show up with optical radar echoes when real targets are crooked Angles are detected. In the measuring range simulator according to FIG. 1, the simulation of the pulse broadening requires the selection of suitable ones Properties for the light-conducting fiber and thus another wound Fiber optics. In the embodiment of the measuring range simulator according to FIG. 2, this target echo selection is relatively simple. With this embodiment a larger expansion or pulse broadening can also be simulated.

If in the simulator according to FIG. 1, an optical delay line of 0.5 km is used, the only target echo normally arrives at the optical receiver, while the latter undergoes sensitivity degradation recovered by the energy content of the trigger signal (main bang), which means that the threshold sensitivity of the receiver is reduced will. "It can be concluded from this that such a simulator is not for the Determination of the round trip operation can be used unless the optical delay line is enlarged to a full one Ensure recipient recovery. With the measuring range simulator according to

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Patent attorneys

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measured Fig. 2 with a variety of reflections can with the help of a optical delay line consisting of an optical fiber of 0.5 km multiple target echoes can be received in the range of the full threshold sensitivity.

The outward and return operation of the system to be examined or the entire dynamic system range is directly dependent on the output power of the transmitter and the receiver sensitivity. With the simulator according to Fig. 1 can be the total attenuation value in the beam path as a measure for this Dynamic range can be used. Thus, with a given optical attenuation in the beam path, the visibility of the nth target echo can be used as an acceptance criterion used for the system. If the "attenuation is inserted in calibrated quantities with the help of the input attenuator, the dynamic range subdivision of the target echoes can be determined. This measurement provides a feature for self-checking of the range simulator according to FIG. 2, since the small dynamic range subdivision of the target echoes minimal optical losses within the optical Indicates delay line. Conversely, this means that large losses within the coiled optical delay power are comparable Absorb blocks of dynamic range per target echo and quickly consume the useful dynamic range and lead to a reduced number of target echoes. The number of target echoes visible cannot be used alone as a criterion for the simulator operation, as this also depends on the available dynamic range of the overall system depends. The dynamic range division of the target echoes depends on the dynamic range of the system and is a direct function of the Optical delay line quality. This dynamic range division therefore offers a reliable and easily measurable criterion for the way of working and at the same time a means of self-examination. When a simulator with multiple reflection is put into operation for the first time, it can be used in conjunction with a system whose overall -

dynamics-

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dynamic range is known. Any vote of a fixed Attenuation in the beam path to achieve a specific echo visibility can be omitted. Then the dynamic Area division of the target echoes measured as described above and compared both with the theoretical precalculations and with the number of target echoes that are within a required residual dynamic range to be expected. A good correlation characterizes a properly working simulator, with the measured Subdivisions serve as reference identifiers to which all further measurements with this simulator can be related.

Special attention to the design with the simulator Multiple reflection is required if the losses in the coiled optical delay power are to be minimized in order to achieve a to achieve the maximum number of target echoes within an available usable dynamic range. Such a maximum The number of target echoes results when:

a) the partial reflector or partial mirror at the entrance surface of the light-conducting fiber in such a way with respect to the transmission-reflection ratio is designed so that this amplifies the higher order echoes in favor of the lower order echoes;

b) the coiled fiber optics at the wavelength of interest Shows a minimum of losses and is attached to the coil in a voltage-free state in order to ensure these minimum losses, and if

c) the losses at the entry and exit surfaces of the optical fiber as well the reflection losses through careful processing of the fiberglass ends as well as through a surface treatment combined with a corresponding one Design of the interface between the glass fiber and the reflector can be minimized.

The ability,

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Patent attorneys

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The ability to accommodate high optical power densities is that Design of the present final construction peculiar. It follows that their use in the simulator according to the Invention allows the use of much higher incident energies than is the case for the simulator according to FIG. As already was explained above, the usable dynamic range with regard to the input power is limited, so that it follows that that with the possibility of absorbing more energy, an increase in the dynamic range and thus the maximum exploitation that depends on it the achievable echoes is connected. One should keep in mind that this mechanism increases the echo yield is completely independent of what can be achieved by reducing the losses in the coiled optical delay line. Of the Success of a practical multiple reflection simulator requires that both mechanisms be exploited in order to obtain maximum echo recovery to pursue. This is the case because there are limits beyond which the echo yield cannot be achieved by the mere use of Energy can be improved. The first obstacle is to be seen in the non-linear behavior of the optical fiber at high energies, which is followed by optical destruction on critical surfaces.

The simulator according to FIG. 2 contains all the important properties of the Simulator according to FIG. 1 without the compromises and represents a further improvement the same in such a way that it shows the following additional skills and characteristics: The simulator is able to deliver a multitude of target echoes through multiple reflection within the optical delay line, which is achieved on the one hand by inserting a planar, partially reflective surface, which with the entrance plane of the optical Fiber collapses, and further through the use of a planar reflector at the end of the optical fiber. Echoed to every target

orderly

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Patent attorneys

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ordered delay shows the stability and the precision that the use is peculiar to a given length of fiber optic.

Measures are also available to control the achievable number of target echoes and - the simulation of the area change for the most distant goal. Finally, costs can be saved by using a relatively short optical Delay line made of a coiled optical fiber to measure distances to simulate the multiple of its own length. There is also a complete recovery of the threshold sensitivity of the optical Recipient.

If it is to be used in conjunction with a system, which contains a precise range graduation, the simulator is able to the length of the optical delay line and then the function to calibrate the range graduation of all systems to be checked. This eliminates the need for a separate procedure for Calibration of the length of the optical delay power and, moreover, an independent possibility of checking the system area linearity.

Finally, by selecting the appropriate target echo, an area can be simulated by values of a real target pulse spread. It is also the possibility of self-examination in the form of measuring the dynamic range distances of the target echoes given, the values of the distances supply a criterion for the operation, which the Form the basis for checking the behavior of the simulator throughout its lifetime. The simulator according to the invention provides a maximum number of target echoes within one available standing dynamic range by using an appropriate technique

and

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Patent attorneys

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and handling the coiled light-conducting fiber, the inherent losses be minimized. Ultimately, a maximum number of target echoes is achieved through the use of a technique which is an improvement and enlargement of the available dynamic range.

Claims

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e e r e i t e

Claims (9)

Claims l.) Passive optical distance range simulator with an adapter for mechanical coupling to an optical radar system, which emits a light beam of a predetermined frequency and receives reflected light radiation and possibly extraneous light radiation, characterized in that an entry opening (6) is provided on the simulator through which the Light beam enters the simulator and through which the reflected light radiation and possibly the extraneous light radiation leaves the simulator that a focusing device (17) is connected in the light path (8, 9, 10) which has a focal point in a common plane with the entrance surface ( 18) has an optical delay line made of a light-conducting fiber (20) or a fiber bundle, and that a reflector (21) is arranged at the other end (22) of the optical delay line opposite the common plane. 2. Passive optical range simulator according to claim 1, characterized in that in the light path (8, 9, 10) a Attenuator (24) is switched on for fine adjustment, which consists of two glass plates (25, 26) arranged at an angle to one another, ORSGiHAL INSF ¹ EC S ED ρ η Q s;. ' 7 / r. ρ 3 η FLEUCHAUS & WEHSER «<· ■ <· ■> SL Our reference: WSl 16P-1745 with which the reflection arising on the first surface deflected the light path and a deflection of the light beam passing through the attenuator is prevented. 3. Passive optical range simulator according to claim 1 or 2, characterized in that a primary attenuation member (12) is also arranged in the light path at an angle to the light path (8, 9, 10). 4. Passive optical range simulator according to claim 3, characterized in that the primary attenuator (12) absorption devices (14, 15, 16) are assigned. 5. Passive optical range simulator according to claim 4, characterized in that the absorption devices have a parallel to the plate-shaped weakening member (12) extending second glass plate on which the from the front surface of the attenuator reflected radiation impinges, and that the second glass plate (14) absorption surfaces (15, 16) assigned which absorb the radiation reflected by the second glass plate and passing through the second glass plate. 6. Passive optical distance range simulator according to one or more of claims 1 to 5, characterized in that that the optical fiber consists of a step index fiber and optionally a gradient fiber with low losses and a mechanical buffer consists of sheathing, which is placed on a supply reel in the form of a series of fully interlayered individual winding layers is wound. Ö098 3 7/08 3 FLEUCHAUS & WEHSER * - "■ · -3" ~ Our mine WSl 16P-1745 7. Passive optical distance range simulator according to one of claims 1 to 6, characterized in that the reflector (21) Reflection properties for the wavelength of the optical radar beam has and at the same time is permeable to the visible light spectrum, and behind which the properties of a partial mirror aufweisendai reflector (21) a light source with a visible Light spectrum is arranged to illuminate the entrance surface (18) of the fiber for alignment and adjustment to the focal point. 8. Passive optical distance range simulator according to one of claims 1 to 7, characterized in that on the Entrance surface (18) of the optical fiber (20) a partial mirror (37) is provided for the wavelength of the optical radar beam trigger multiple reflections of the pulsed optical radar beam within the optical fiber for detection by the system. 9. Passive optical distance range simulator according to claim 8, characterized in that devices for the adjusted setting of a distance of the rear end (22) of the fiber to Reflector (21) are present. 8 0 9 B 3 7/0 8 Ί 7