DE2518209B2 - METHODS AND DEVICES FOR THE PHOTOELECTRIC DETERMINATION OF THE POSITION OF AT LEAST ONE PLANE OF FOCUS OF AN IMAGE - Google Patents

Description

2. device for carrying out u .. »method for Fntiernungsmessungen with at least one imaging optics, at least one optically effective grid structure and one of these associated photoelectric receiver system having optical Uorrelator ^c ystem, characterized in that at least two radiation guidance and receiver systems with different radiation guide elements provided are which ever a

ve the relative position between the object and the optical correlator system periodically dependent output

Signal period and arial relative position for the Sirahlenführungsystei ·. e are preferably not different from one another, and that the photoelectric receiver systems assigned to the line guidance system are followed by a comparison circuit {6b, 66) which itself overcomes by comparing the electrical signals obtained from the different radiation signals Periods unambiguous, position-determining electri «. '- <· supplies output signals

3. ESTABLISHMENT _fa according to claim 2, characterized gekennzeichnt as Λ for the purpose of separation of the no MeQin.jnna> in-containing signal components of each beam guiding YSTEM a circuit (60-63) nachgeordne; is made up of two output signals of the

he prechenden Empflngersystems (2C -17) forms a third, purified signal which is as an input de-ι Vr e'leichsschaltung (Bae, 6 ") luge ^case brings

4. Arrangement according to Anspn.ci «2 or 3, thereby

Grid structure a grid arrangement (10 ', / 5, 100) with after. Marks splitting in four directions is provided and that in the imaging system optically effective means (43) for generating at least two different azimuth angles corresponding to the measurement coordinates of the grid arrangement associated parallactic measuring angle are provided.

7. Device according to one of claims 2 to 4, characterized in that as optically effective Grid structure, a grid arrangement (110) is provided with markings which split in four directions is and that the associated photo-electric receiver systems (32, 32 ', 33, 33') are arranged in such a way are that by the lie of their recipients defined parallactic angle are different from receiver system to receiver system.

8. Device according to claim 6, characterized in that the imaging optical system (11) is assigned at least one diaphragm (40, 43), the recess (41) or recesses (44-47) define four pupil areas or pupils Focal points (P _x , P _y ) in pairs have preferably the same distances from the optical axis of the system (11), the distances between two pairs of pupils or pairs of pupil areas being unequal (unequal parallax).

9. Device according to one of claims 4 to 7, characterized in that the markings of the Grid structure (100) have triangular cross-section in at least one direction.

10. Device according to one of claims 4 to 7, characterized in that the markings of the grid structure are trapezoidal in at least one direction Cross-section indicator (F i g 2a).

11. Device according to claim 4, characterized in that aaV - <inn ^ aiQhriet Haft / Jig Ractprginiktiir

two corresponding to the desired coordinate direction contains oriented, one-coordinate grids (Fig. 2c). *

12. Device according to claim 2 or 3, characterized in that the markings of the grid structure have different flank angles (F ig. 2b).

13. Device according to claim 2 or 3, characterized in that the grid structure between their markings have different groove depths (FIG. 2b).

! 4. Use of a device according to one of the preceding claims 2 to 13 in combination with a projection device that projects at least one grid structure onto the object to be measured.

60

itruk jr a grid arrangement (W, 75 - Fig.2a, 2c) m 11 in two azimuths with different pitches, *, Periods is provided.

5. Device according to claim 2 or 3, characterized in that dsB g'ss optically v / irkssms Rasterstrufctü 'one grid arrangement (I ^ T, fäffl · »iß, I © 2) is provided, which has two different Teuiingspsrioden in an Asimui miiidesiens.

β. Device according to one of Claims 2 to 4, dsdu.-ch ggkesnssicendet, d§0 gis optically wlrksaras Determination of the position of at least one focal plane of an image within an optical device with mapping of at least one object to at least a spatial frequency filter of an optical image corrector and measurement and / or display of the d? s Qrisfre · quensfiher left a LichtHusses and Είπποδΐοη * gen to perform this procedure.

A similar method is described in the DT patent 23 30 94ö, in which different pupil areas of the eyelid - end optics dyrchlaufead i light fluxes.

jointly modulated by the spatial frequency filter and split geometrically or physically or by an additional modulation according to the pupil areas and then fed successively or simultaneously to a common photoelectric receiver s or separate photoelectric receivers, the output signals of which are further processed for the purpose of controlling a display and / or tracking device . In addition, for the purpose of controlling with the correct sign, a | _O display and / or control device that determines the size and / or, in the case of a relative movement between spatial frequency feeder and image, the phase position and / or the frequencies of the electrical signals generated relative to one another. Also, when using a spatial frequency filter arrangement that generates push-pull light fluxes, the light fluxes breathing through the different pupil areas of the optics can be fed to a common photoelectric receiver pair after their splitting H j * "a push-pull pair. -sgangssignaie for each pair of receivers assigned to a pupil area in a known manner:; em push-pull amplifiers were supplied, the output signals of these amplifiers then for the purpose of correct control of a display and / or tracking device with regard to size and / or - in the case of a relative movement between spatial frequency filters and picture - mutual! Phase position or frequency can be compared with each other.

As has been shown, the signals obtained by the method are good for measuring the distance and suitable as control signals for an adjusting device. But it has also been shown that this Only move the position of the image plane or the distance position clearly within a limited area mediated It is shown that there is a periodicity in the evaluation signals that leads to ambiguities Cause. Does one move with the image plane within one? Location area, which is a half Corresponds to the signal period, only one signal maximum appears when passing through the range, the position of the image plane can be clearly determined. Now assign two photoelectric ones to a grid To the receiver and drive through the imaging area of the optics with this grid, they have

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the sharpness Riehene not only mavjmale amplitude but it ^s: nd ".u'ch phase; the phase of one or the other signal precedes the phase of one or the other of the signals, depending on the direction of migration of the grid out of this plane along the optical axis. It is now possible that the object to be measured is in the area and another object is located at a different distance, the latter providing a higher signal level than the measuring area due to its power (e.g. the rear light of a motor vehicle) than the measuring area and thus pin " Misinterpretation and thus a wrong measurement causes The above-mentioned flat effects are all the more proportionate, the larger the Be'-I is that one would like to capture, and the more one moves from the far range to the nabberexh

The invention relates to a method of the type mentioned at the outset, which is characterized by this net that for the purpose of the clear determination of distance by optical-geometric measures in the Image space and / or different in Fourier space Beam guidance systems are generated so that bc, an axial relative movement of an object image relative to the grid structure on each of a beam guide associated photoelectric receiver system cm output signal arises from the one other beam guidance obtained output signal always with respect to its frequency rad thus its phase distinguished, and that these two output signals are then compared with each other and from the comparator Result is the geometrical position of the main maximum compared to the geometrical position of the secondary maxima is determined.

A device for carrying out this method with at least one imaging optics, at least one optically effective raster structure as well as a K'jrrelatcrsvstem assigned to this associated photoelectric receiver system is characterized = that at least two Sirahlenführung- and receiver systems are provided with different beam guidance elements 1, which each delivers an output signal periodically dependent on the relative position between the object and the optical correlator system, the dependency between the signal period and the axial relative position for the beam guidance systems preferably not being mutually harmonic and where the photoelectric receiver systems assigned to the beam guidance systems are followed by a comparison circuit, which by comparing the electrical signals obtained from the different radiation guidance systems themselves ^c £ ord

Provides ear-to-electrical output signals

For the purpose of separating the signal requests which do not contain any measurement information, a circuit can be arranged downstream of each beam guidance system, which forms a third, purified signal from two output signals of the corresponding receiver system, which is fed as an input signal to the comparison circuit. As the optically effective structure is a grid lattice arrangement can with different azimuths in two division periods UEDE ^{r e;} The grid arrangement which has in tifiCm AZilTiüi minucStcnS iwci ünicfsChicdüCiic aci- Iungspenoden, or a grid arrangement with markings splitting in four directions and assigned optically effective means in the imaging system for generating at least two corresponding to the measurement coordinates of the grid arrangement. ' be different Azimutwmkein associated paraüaktischer measurement angle, or a lattice arrangement with splitting by vbr directions marks and so seconded fotoe'ekirischen receiver systems hatred Hip diicph Λιο {αβ "ih"> o- Pmr.fänooi · defined parallactic angle of the receiver system to the receiver system are different, provided .

Ls can also map the optical system at least one diaphragm assigned to S £ in ^ whose outer pa-

Pupillehdefiriiertir., Whose focal points in pairs for optical axis of the system usually = same Have distances, wherein; the distances = two BipiKenpaare or PfeAttJiereishspaare are not equal (unequal papailaxe ^ the markings of the raster

structure can be triangular in at least one direction or trapezoidal cross-section. They can also have different flank angles.

The invention is described below with the aid of schematically illustrated exemplary embodiments.

It shows

Fig. 1 is an illustration for explaining how it came about the signal maxima,

ρ i g. 2 entry device with two coordinate directions having different grace periods buttons or goods.

2a-2c embodiments for the detent or grid.

3 - 3b embodiments with after one Coordinate oriented grids or grids,

p, g.4-4b examples with different pupillary centroids,

F ι g 5. 5a an embodiment in connection with a camera.

Fig. *) 6a an execution form in connection with a projector

In FIG. 1, an objective II forms an object 12 in ε-.ne Level in which an amplitude grating 10 is movably mounted and from a generator 14 in oscillatory Movement parallel to the plane of the drawing and 'is offset perpendicular to the optical axis. The grid downstream there are two photoelectric receivers 8,9, which, due to their spatial position, are assigned to different pupil areas of the lens.

Both deliver for the shown position of the grid Receiver alternating signals of maximum amplitude and the same phase position. If you now change the distance between lens and grid, the signal amplitudes decrease continuously, occurs simultaneously Phase shift of the output signals of the receivers 8, 9. where the direction of movement is the The focal plane determines which signals precede. The phase shift can in principle also be several Cycle through signal periods. In each case the frequency of the signals is given by the lattice constant and Determines the speed of the grid movement

The invention was based on the idea that when measuring the distance with the after a The signals obtained from the coordinates of the field of view are sufficient if the change in distance of the object to shift the plane of focus

leads in the range of a signal phase change from + y to - ^. In addition, there are ambiguities

to be eliminated

But one can only use one coordinate direction of the field of view to obtain the measurement signal is another coordinate system of the field of view for obtaining defining auxiliary signals use. This is particularly successful if the two coordinate directions are rastered from one another assigns different division periods. In this case the output signals are from the photoelectric receivers assigned to different coordinate directions in their frequency different from each other, and it can be seen from the phase position of the mutually different signals the position of the focal plane, which is determined by the maximum output signals from the receivers of the measuring coordinates defined is to be determined with certainty. If one uses, for example, grids whose division periods are in Ratio 1: 10 are, so occurs, of maximum measurement signals starting, this in the same phase relation to the auxiliary signal only after ten periods of the auxiliary signal back on. So you have it in hand through the appropriate choice of the grid, the uniqueness of the To enlarge the measuring arrangement and thus the distance measuring range to expand the measuring arrangement.

A corresponding embodiment is shown in FIG. 2 shown. The object not shown is used by

ίο a lens U mapped onto a grid 10 'with marks of triangular cross-section, which is borrowed according to two mutually perpendicular coordinate directions x, y and has different pitch periods for these coordinate directions. This

■ 5 grid is mounted by means of two flexural oscillators 13 attached to it diagonally and can be controlled by controlling these flexural oscillators by means of a «; Generato · s 14 in the direction oblique to the two coordinate directions κ. y can be moved in an oscillating manner. A field lens 15 follows the razor 10 'and images the entrance pupil of the objective 11 in plane 16. At this level four \ aare photoelectric receivers are 20 to 27 gelac Oa the grid splits the Eintritispupille in four austrug ilen, act on their images

2s each with a pair of receivers. According to the above Patent, the receivers are shaped and mounted in such a way that two of them emit light different parallactic angles obtained from the object, ^ speaking a right and a left

ίο or an upper and a lower part of the entrance pupil. The signals of the receivers 20, 22 or 21, 23 or 24, 26 or 25, 27 are in push-pull to each other. They are fed to push-pull amplifiers 60, 61, 62, 63, which sum their input signals and at the same time eliminate common-mode components and interference components. The output signals obtained in this way are now fed in pairs according to the coordinate direction assigned to them to a phase comparison stage 65 or 65, the output signals of which are dependent on the respective phase difference of the input signal and which is directly proportional or proportional to an angle function corresponding thereto. When the object distance changes, in the second case an output signal with a periodic profile results for the coordinate direction, but in the two coordinate directions with a different relationship between the change in distance and the period length. The two signals are fed to a ratio generator 67 which compares the respective instantaneous values and whose output signals are used to identify the period of the above-described distance signal. In addition, the signal of at least one coordinate is used for measurement within the period, using its phase position. In addition, by using a reference signal derived from the oscillating movement of the grid by means of at least one phase-sensitive rectifier 68 shown in dashed lines, a signal can be derived from the original output signals of push-pull amplifiers 60 to 63 which is proportional to the object displacement perpendicular to the optical axis in up to 2 coordinates (display 69). Using the reference signal from the scanning movement by comparison with at least one of the output signals of the amplifiers 60 to 63, output signals can also be obtained which correspond to the change in position of the object perpendicular to the optical axis.

2 § 18 209

Raster IC can be implemented in different ways. On the one hand, it is possible to achieve the different graduation periods assigned to the two coordinate directions by using a hipped roof-like or hipped roof-like razor with non-square marks ^; Bases generated. ' ¹ An example is shown in Fig.2a, where the ¹ dashed lines define the outer surface of the grid when designed as a hipped roof-like grid. Fig. 2b shows an 'embodiment, -in which the' flren by H ^ valleys formed if .the Talsache / that the 'MarJc'en with square base ¹ in the two' Kobrdinat ^ nrtchtiiTigen 'Different having ¹ Flankenneifungen, the ensprecnend / oordinaienricbtungen ur'erschisdlich deep smd. Fig. 2 shows a grid which is composed of two jin-coordinate prism grids of different graduation periods, these two prism grids being at 90 ° with their graduation directions against each other. twist against each other

With the previous description, be level after two different coordinate directions used grids having different graduation periods But it can be seen that: I am the apedefmition required signals of different F-req ^ -. z also by splitting object 12 * on two assigned to the same coordinate direction, under simultaneously depicts grids with different graduation periods, whereby these frames are close to each other and their light has a common optic can get.

It is also possible to design the raster after the objective to be one-coordinate in order to map the object onto an auxiliary raster via a second objective, whereby the measuring raster and auxiliary raster meet the above-mentioned conditions and, according to the directions determined by their markers, are assigned different or "even assigned to the same coordinate direction" . An example of this is shown in Fig. 3. The lens! 3 images the object (not shown) onto a prism grid 100. which upper collecting lenses 30,3t are followed by photoelectric receivers 32,33 whose output signals are in push-pull due to the geometry of the grid 100. A corresponding arrangement of components is shown above, with their components each marked with an added stitch. For them, the same applies to the output signals as for the lower arrangement. The two lenses 11, 11 are as close to one another as possible and are coupled to one another, so that any spatial shifts can be made. .oiJföhrt. The two grids 100 and 100 'have different graduation periodsa from one another, so that the output signals of the photoelectrically ^ ;; Receivers 32, 33 have a different frequency than that of the receiver 32 *. 33 '. Not shown are drive means which set the grid in synchronous oscillatory movement according to the double arrow 35. They are preferably fed by a generator 36. The signals are evaluated in the manner described above.

Variations on this arrangement are possible. So can, if there is enough light, the lens 11 “Can also be used for imaging on both Raster 100 and IOC by placing between lens and Plaster 100 attaches a corresponding geometric or physical beam splitter the proportions of the light flux assigned to the grids be quite unequal, since it in by means of the Hüfsrasters ICS 'wesentlicnsn jm generated signals arrives at their phase position,' which is ⁵ used to define the position of the image plane. An example ■> this is in g F ΐ. 3a-As can be seen, a geometrical "beam splitter" ICä is arranged downstream of the objective 11, which guides the light fluxes corresponding to a pupillary field of the objective 11 onto the grid 100 while the "light flux" is directed from the others

ίο the pupil half lengthened to the grid 400 * i '"' ■ ' i v Both razors are in turn mechanically rigidly coupled to one another: They show the same in their periods, but in ^: t> ren flank angles ** ^ln ■!« »« • rschie 'toe'ie Prisrnei * on and are under control by the generator

14 is surrounded in a direction perpendicular zw mark r; moved. Ann to dit point of the divider 108 \ also, as indicated by dashed lines. a physics? Step over beam splitter 107. It is also possible to distinguish between the two grids!) before Pnnillenbereiche to you, as> the ir Fig io gezeigtjn Be'spiel the case isi. The object is YI ft above the lens with pre scarf ·; 11 displayed 'em Bi wedge, and the two grid'<M and 102 facing each other un v.hiedliche Tt jungspeno which have, are assigned to different P'piilenhälften the objective 11. They are mι rigidly coupled to one another and are moved under the control of a generator i in the direction perpendicular to the characters bc .-. E. The downstream photnc'electric Receivers 103 and 1G4, in cooperation with the light fluxes reaching them through field lenses 15, supply output signals which vary in frequency differentiate according to the formation of the grid These signals are processed in the same way as described above.

But if you want to get the signals, namely the measurement signals and those defining them Kilfssignals, from two coordinate directions, cannot be dispensed with, so one can also use one afterwards grids with the same division periods in two coordinate directions can be achieved if one cares about it carries that the coordinate directions pupil areas with different distances between their centers of gravity are assigned This can be, for example, through

Use a lens with an elliptical aperture or achieve this by assigning an appropriate aperture to the lens. Examples of such Apertures are shown in FIGS. 4a and 4b shown while FIG. 4 the basic structure of the overall arrangement In FIG. 4a, the objective 11 is assigned a diaphragm 40 with an oval recess 41 which, through its shape, determines the position of the pupil centers of gravity Px and Pp. In the example according to FIG. 4b weaves the panel 43 four recesses 4 & round to 47 Cross-section, the centers of which coincide with the pupillary centroids Px and Py . As can be seen, the pupil centers of gravity Px to one another or the pupil centers of gravity Py to one another have different distances, they are different before parallax angle assigned from what together act with a grid HO, which has the same graduation periods for both coordinate directions, with different electrical frequencies Scanning signals result, with the shorter pupillary

The center of gravity corresponds to the higher-frequency signals. It is not absolutely necessary that the center of gravity of the pupils in a coordinate direction is the same distance from the optical axis of the system

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'Volume 43 can be dispensed with if one ensures that the photoelectric receivers do so designed and arranged that they are of Pupillary area? with different distances? of their The radiation components which have been given focal points to be hit. An embodiment for a Such a receiver arrangement is shown in Fig. 5, its special .yirwondung in aßKainera shown in Fig. 5a. In the F i fr. 5 fields shown in dashed lines correspond to the ^ Stnu'iHjngsanteüen, the ^ forwarded to viewfinder .iwe.rdea and therefore no longer used for the measurement To be available. ■

in F1 g. 5a, a splitter or folding mirror 59 is intended between the members of the camera lens Sf, which diverts at least part of the incident light flux laterally into a viewfinder beam path. The optical elements 53, 55 in connection with a diaphragm 54 are designed in such a way that the object is imaged on an annular mirror 50, through the opening of which the radiation component for the viewfinder with his eyepiece 53 passes 'thrown, which makes them By J ^K 50 of an optical device 57 supplies the hole of the annular mirror, which in accordance with d "* ri above, is constructed the figure shows that the new device is applicable also in a camera without a lot of space

So far it has been assumed that the to be measured Object itself has enough structures. which ensure sufficient measurement signals. Well there But there are cases in which this is not the case Object to project a structure, soft in relation to the image · its period of division in the plane of the Grid coincides with the division period of the latter (see patent application P 24 03 5185). This The method can also be used in the context of the present invention if the projected one is used Structure-providing grids as cross grids with different in two coordinate directions of the image plane Training periods * and as a sensor grid, preferably "in a pyramid grid, provides that with its different periods of division the image of the structure door having different periods of division is equivalent to. The grid is as mentioned above across the coordinate directions in oscillating Moves offset and then the light from the image space for the two coordinate directions on each e'i recipient pair directed where «wiitehe»; in the Object space multiple intersecting rhombic ray geometries that result from the projected structure and emerge from the virtual image of the grid. Around t ^ isnuf eleven τ given neripjrallafctischewJBasis -τ per se are also arrangements with two bases z. B. in Höfoen- and side direction possible - with simple means get along, both cross grids under z. B. 45 " arranged rotated to the base in the image plane, whereby the door both Kaoräiftatenrichtungen one component the base and the oscillating movement of the grid comes into effect

With such an arrangement? can for the projection device Only 1 the sensor can be used with a common lens, preferably by means of a geometric beam splitting in the vicinity The pupil and parallanep centers of gravity separated from the entrance pupil for the raster piojection and the. «or arise. An example of such an arrangement is in fig. 6 and 6a shown. A common lens 7 © is both the au · * a light source 71, a Condenser 72, a grid 73 which supplies the projected structure, and a deflecting mirror 74 Projection device as well as the oscillating grid 75 (indicated by arrows), a <= r Field lens 76 assigned to both a photoelectnschen receiver system 77 existing sensor, wherein only one lens half is used in each case. Both the grid of the sensor (FIG. 6a) and the grid of the Projection device s.ad arranged so that the coordinate directions defined by them are oblique to the The direction of oscillation of the grid 75 is available. The equatorial base is denoted by ο.

It is easy to see that in the individual Examples used grids can be replaced by grids of a different type if adapted accordingly can.

It also remains to be mentioned “that what is described above The procedure and the facilities for its implementation can also be used in eye refractomy can.

For this purpose 5 sheets of drawings ■ . Λ,

Claims (1)

L.MaA JaQ al «*» ■ »». π IO Patent claims: I. Distance measurement method miri at least one optical system, at least one optically effective grid structure and a this associated photoelectric receiver system having optical! Correlators, da-.tfiirch characterized that for the purpose of clear distance determination by optical-geometric measures in the image space • and / or different beam guidance systems in the Fourier space are generated, so that with an axial relative movement of an object image rel itively xur raster structure on each photoelectric receiver system arranged in a beam guide tin output signal is generated that differs from the output obtained from another beam guidance input signal always with regard to its frequency and am with its phase differs, and di.3 this the two output signals are then compared with one another and the geometrical one from the comparison result Image position of the main masimuniE opposite the. geometric positions of the secondary maxima determined