DE102022200195A1 - Optical position measuring device - Google Patents

Abstract

The present invention relates to an optical position measuring device for determining the position of a first object, which can be moved relative to a second object along a measuring direction. A material measure with a measuring scale extending along the measuring direction is connected to the first object. A scanning unit is connected to the second object, which includes at least one light source, a detector, and a lens array for imaging a measurement graduation region onto the detector. The lens array has a multiplicity of adjacently arranged individual lenses on only a first side; a plurality of reflectors are arranged at least in partial areas on an opposite, second side. The individual lenses produce a reduction image of the measurement graduation area in an intermediate image on the reflectors; the intermediate image is then magnified via the individual lenses into the image of the measurement graduation area on the detector.

Description

FIELD OF TECHNOLOGY

The present invention relates to an optical position measuring device for determining the position of a first object, which can be moved relative to a second object along a measuring direction.

STATE OF THE ART

A generic optical position measuring device is from DE 103 17 736 A1 known. This comprises a material measure connected to a first object with a measuring graduation extending along the measuring direction. A scanning unit is also provided, which is connected to a second object and has at least one light source, a detector, and a lens array for imaging a measurement graduation area onto the detector. The first and second objects are arranged to be movable relative to each other along the measurement direction. The lens array is used to transfer or image part of the measurement graduation, which is in the form of a pseudo random code, onto the detector; the lens array is in this case designed as a transmittive cylindrical lens array. It essentially consists of a transparent, cuboid body that has a large number of individual lenses on two opposite sides; the corresponding surfaces of the body are suitably structured for this purpose. Via the individual lenses arranged on a first side, a reduced intermediate image of the measurement graduation area within the lens array body is initially produced. The intermediate image generated is then enlarged and projected onto the detector via the individual lenses on the opposite side. The overall image scale of the two partial images is preferably 1. The production of the lens array is complex because of the necessary structuring of the two body surfaces to form the required individual lenses, since this requires several lithography steps on both surfaces. In addition, the described imaging with two partial images and an intermediate image within a lens array body that is as thin as possible results in comparatively large object distances in the first partial image; likewise, relatively large image widths result in the second partial imaging. This results in a comparatively large space requirement for the corresponding image.

A similar position measuring device is also from JP 2015-081794 A2 known. In contrast to the above solution, no purely transmittive lens array is provided here; Rather, additional mirror surfaces are arranged inside the array body, via which the beam bundles are deflected between passing through the individual lenses on the opposite sides. The corresponding lens array can thus be designed to be somewhat more compact, but the manufacturing complexity for the individual lenses required on two surfaces is also high with this solution.

SUMMARY OF THE INVENTION

The present invention is based on the object of specifying an optical position-measuring device which, for imaging measuring graduation areas on a detector, comprises a lens array which is as compact as possible and easy to manufacture.

According to the invention, this object is achieved by an optical position measuring device having the features of claim 1 .

Advantageous embodiments of the optical position measuring device according to the invention result from the measures that are listed in the dependent claims.

The optical position measuring device according to the invention is used to determine the position of a first object, which can be moved relative to a second object along a measuring direction. It includes a material measure connected to the first object with a measuring graduation extending along the measuring direction. Furthermore, it includes a scanning unit, which is connected to the second object, with at least one light source, a detector, and a lens array for imaging a measurement graduation area onto the detector. The lens array has a multiplicity of adjacently arranged individual lenses on only a first side; a plurality of reflectors are arranged at least in partial areas on an opposite, second side. The individual lenses produce a reduction image of the measurement graduation area in an intermediate image on the reflectors, and then the intermediate image experiences an enlargement image via the individual lenses in an image of the measurement graduation area on the detector.

Advantageously, the lens array is used to image the measurement graduation range onto the detector with the imaging scale β _tot =1.

It can be provided that at least one reflector is assigned to each individual lens on the second side of the lens array.

In this case, each reflector is preferably arranged on the second side in the course of the imaging beam path centered on the middle of the associated individual lens and has a surface that is dependent on the partial image scale β1 of the reduction image.

Alternatively, it can also be provided that on the second side of the lens array the areas between the partial areas with the reflectors are also designed to be reflective, so that a continuous reflector is arranged there.

It is also possible for a deflection element to be arranged in the imaging beam path between the lens array and the detector, which deflects the imaging beam bundles coming from the lens array in the direction of the detector, with the first side of the lens array facing the deflection element.

In this case, the deflection element can be designed as a deflection mirror, the reflecting side of which is acted upon by the imaging beams of rays.

Provision can furthermore be made for the first side of the lens array to face the reflecting side of the deflection mirror.

The deflection element is advantageously arranged centrally between the measurement graduation plane and the detection plane.

Provision can also be made for a deflection element to be arranged between the scale and the lens array, which deflects the bundle of rays coming from the measuring graduation in the direction of the lens array.

• - das Umlenkelement als Umlenkspiegel ausgebildet ist, dessen reflektierende Seite von den von der Messteilung kommenden Strahlenbündeln beaufschlagt wird, und
• - die erste Seite des Linsenarrays in Richtung des Detektors orientiert ist, und
• - das Umlenkelement mittig zwischen der Messteilungs-Ebene und der Detektions-Ebene angeordnet ist.

It is possible that

• - The deflection element is designed as a deflection mirror, the reflecting side of which is acted upon by the beams coming from the measuring graduation, and
• - the first side of the lens array is oriented towards the detector, and
• - the deflection element is arranged centrally between the measurement graduation plane and the detection plane.

Furthermore, the measuring graduation can be designed as a reflection measuring graduation, which has graduation areas with different reflection properties arranged alternately along the measuring direction.

Furthermore, it is possible for the measuring graduation to be in the form of an absolutely coded measuring graduation.

A decisive advantage of the optical position measuring device according to the invention is that the reflective lens array used therein can now be manufactured particularly inexpensively. Only a single side or surface has to be structured in order to form the required individual lenses there. Furthermore, the result is a significantly more compact structure for the implementation of the imaging than in the solutions known from the prior art, so that a scanning unit of particularly small construction can be implemented.

Further details and advantages of the present invention are explained using the following description of exemplary embodiments of the device according to the invention in conjunction with the figures.

character list

• 1a eine schematische Darstellung zur Erläuterung des Abtaststrahlengangs eines ersten Ausführungsbeispiels der erfindungsgemäßen optischen Positionsmesseinrichtung;
• 1b eine Draufsicht auf die Maßverkörperung der Positionsmesseinrichtung aus 1a;
• 2a - 2c jeweils eine unterschiedliche Ansicht des Linsenarrays aus dem ersten Ausführungsbeispiel;
• 3 eine Teil-Darstellung des entfalteten Abtaststrahlengangs zur näheren Erläuterung des Linsenarrays;
• 4 eine alternative Darstellung zur Veranschaulichung verschiedener geometrischer Größen des ersten Ausführungsbeispiels;
• 5 eine schematische Darstellung eines zweiten Ausführungsbeispiels der erfindungsgemäßen optischen Positionsmesseinrichtung.

It shows

• 1a a schematic representation to explain the scanning beam path of a first exemplary embodiment of the optical position measuring device according to the invention;
• 1b a plan view of the material measure of the position measuring device 1a ;
• 2a - 2c each a different view of the lens array from the first embodiment;
• 3 a partial representation of the unfolded scanning beam path for a more detailed explanation of the lens array;
• 4 an alternative representation to illustrate different geometric sizes of the first embodiment;
• 5 a schematic representation of a second embodiment of the optical position measuring device according to the invention.

DESCRIPTION OF THE EMBODIMENTS

A first exemplary embodiment of the optical position measuring device according to the invention is described below with reference to FIG 1a , 1b , 2a - 2c , 3 and 4 explained.

The position measuring device shown comprises a measuring scale 10 connected to a first object (not shown) and a scanning unit 20 movable relative thereto along the measuring direction x, which is connected to a second object (also not shown). The two objects can, for example, be machine components that can be moved in relation to one another, with the device according to the invention being able to be used, for example, to determine the position of the first object in relation to the second object. The position signals generated with the aid of the position measuring device can be transmitted to a machine controller, which uses them to position the machine components.

In the illustrated embodiment, a relative mobility of material measure 10 and scanning unit 20 is provided along a linear measuring direction x, i.e. the corresponding position measuring device is designed as a length measuring device. Of course, it is also possible to alternatively design the position measuring device according to the invention to detect rotational relative movements of two objects about an axis of rotation. In this case, the measurement direction then runs in the form of a circular ring around the axis of rotation.

In 1b a plan view of the material measure 10 used in this example with a reflective measuring graduation 11 is shown. As can be seen from the figure, the measuring graduation 11 extends along the measuring direction x and consists of rectangular graduation areas 11a, 11b with different reflection properties arranged alternately along the measuring direction x. In this case, the division regions 11a shown dark in the figure have a lower reflectivity than the division regions 11b shown light. In the present case, the measuring graduation 11 is in the form of an absolutely coded measuring graduation whose graduation areas 11a, 11b are arranged aperiodically along the measuring direction x according to a suitable pseudo-random code. The absolute position of the movable scanning unit 20 relative to the stationary material measure 10 along the measuring direction x can thus be determined via the illustrated exemplary embodiment of a position measuring device according to the invention.

Of course, as an alternative to this, the scanning unit 20 can also be arranged to be stationary and the scale 10 can be arranged to be movable along the measuring direction x. It would also be possible for the measuring graduation to be in the form of a transmittive measuring graduation, which then has graduation areas with different transmission properties.

Provision can also be made to arrange one or more incremental graduations in parallel, additional tracks in addition to the absolutely coded measuring graduation 11 on the scale 10 and to process the position signals from the various tracks to form high-resolution position information.

On the scanning unit 20 side, a light source 21 with collimation optics 22 arranged in front, a lens array 23, a deflection element 24 and a detector 25 are provided in the exemplary embodiment shown. The beam emitted by the light source 21, which is in the form of an LED, for example, is transformed by the collimation optics 22 into a parallel or collimated illumination beam and is applied to the measuring graduation 11 on the scale 10. It is provided that the illumination tion-ray bundle as from 1a the measuring graduation 11 can be seen obliquely illuminated. In other words, the illumination beam bundle is incident on the measuring graduation 11 in the yz plane at an angle −θ with respect to a normal N and is reflected at the angle +θ in the direction of the lens array 23 . The absolute value of the angle θ is preferably selected in the range [10°...50°].

The lens array 23 is used to image the measuring graduation area acted upon by the illuminating beam onto the detector 25 , ie a section of the pseudo random code of the measuring graduation 11 is imaged via the lens array 23 in the detection plane of the detector 25 . The image preferably has an image scale β _tot =1, so that a light pattern that is identical in orientation and size to the illuminated measurement graduation area on the detector 25 results. In this exemplary embodiment, a deflection element 24 is also arranged in the scanning beam path between the lens array 23 and the detector 25 and is designed as a planar deflection mirror. The deflection mirror has a reflecting side 24.1, which faces the first side 23.1 of the lens array 23, so that the imaging beam bundles coming from the lens array 23 are deflected in the direction of the detector 25. In the example shown, the plane deflection mirror is arranged parallel to the measuring graduation plane in the scanning unit 20, its reflecting side 24.1 faces the first side 23.1 of the lens array 23 and the detector 25.

The detector 25 is embodied, for example, as a line detector which comprises a large number of light-sensitive, rectangular detector areas which are arranged periodically along the measuring direction x. The absolute position of the movable scanning unit 20 along the measuring direction x can then be determined in a known manner from the transmitted image of the measuring graduation area via a signal processing unit (not shown).

What is decisive in the position measuring device according to the invention is the design of the lens array 23 for imaging the measuring graduation section onto the detector 25. 2a shows a sectional view of the lens array 23 in the xz plane, 2 B a plan view of the first page 23.1 and 2c a top view of the second side 23.2 of the lens array 23. In contrast to the solutions explained at the outset, this is designed as a reflective lens array 23, which in this case consists of a base body made of glass, glass ceramic or plastic, which only has a large number of adjacently arranged on a first side 23.1 Individual lenses 23.L and on an opposite, second side 23.2 a plurality of reflectors 23.R arranged at least in partial areas. The individual lenses 23.L are each designed as identical cylindrical lenses which are arranged adjacently one after the other along the measuring direction x, ie a one-dimensional arrangement of cylindrical lenses is provided on the first side 23.1 of the lens array 23 along the measuring direction x. The individual cylindrical lenses extend - like out 2 B visible - in each case along the y-direction, which is oriented perpendicular to the measuring direction x. For example, gold-coated partial areas on the second side 23.2 can function as reflectors 23.R. According to 2c the corresponding partial areas are rectangular, with the longitudinal axes of the rectangle extending along the y-direction like the cylindrical lenses on the first side. The reflecting side of the reflectors 23.R faces the individual lenses 23.L on the first side 23.1 of the lens array 23, with each individual lens 23.L being assigned a reflector 23.R on the opposite side of the lens array 23. The reflectors 23.R are arranged in such a way that they are centered—in the course of the beam—to the center of the associated individual lens 23.L on the first side 23.1. Because of this construction and the individual lenses 23.L provided only on one side, there is no need to laboriously process two surfaces of the lens array 23 in order to form the required individual lenses 23.L therein.

The optical mode of operation of a lens array 23 constructed in this way is explained below with reference to FIG 3 explained. This shows in schematic form the unfolded or stretched scanning or imaging beam path in the area between an illuminated measuring graduation area 11 _MB and the image 25 _B of the measuring graduation area 11 _MB on the detector; the image resulting from a single lens 23.L is shown here. Not in 3 the deflection element 24 is shown for reasons of better representation 1a .

The individual lenses 23.L arranged on the first side 23.1 of the lens array 23 initially produce a reduced image of the measurement graduation range 11 _MB with a partial imaging scale β1 in a direction-inverted, reduced intermediate image 23 _ZB on the reflectors 23.R, which is on the second Page 23.2 of the lens array 23 are arranged. The partial imaging scale β1 is negative here, for its amount |β1| < 1 applies. The direction-inverted, reduced image of the measurement graduation range results in that plane in the lens array 23 in which the reflectors 23.R are arranged. The flat Expansion of the individual reflectors 23. R depends on the selected partial imaging scale β1; if, for example, β1=−1/5, the partial areas with the reflectors 23.R each have only 1/5 of the area of the associated individual lens 23.L on the opposite side. The design of the second side of the lens array, which is only reflective in partial areas, proves to be advantageous, since this avoids disruptive reflections and the tolerance to scanning distance fluctuations can be improved; moreover, reflector material can be saved.

After reflection at the reflectors 23.R, the result of passing through the individual lenses 23.L again on the first side in the opposite direction is an enlarged image of the intermediate image 23 _ZB in an image 25 _B of the measuring graduation range 11 _MB on the detector 25. The enlarged image has a Partial imaging scale β2, which is also negative and for whose amount |β1| > 1 applies. As already mentioned above, the resulting imaging scale of the lens array 23 is selected according to β _tot =1, ie β1 · β2 = 1 applies.

about the inside 1a The deflection element 24 shown in the imaging beam path between the lens array 23 and the detector 25 ensures that the resulting image 25 _B of the measurement graduation range 11 _MB is recorded at a suitable position in the scanning unit 20 and the detector 25 can be arranged there.

Based on 4 further design aspects relating to the first exemplary embodiment of the position-measuring device according to the invention are explained below. The figure shows various geometric variables that play a role in the imaging of the measurement graduation range on the detector, which takes place via the lens array.

mit:

I1

Objektweite der Linsenarray-Abbildung (Distanz zwischen Messteilungs-Ebene und Einzellinsen-Ebene)

I2

Distanz zwischen Einzellinsen-Ebene und Umlenkelement-Ebene

I3

Distanz zwischen Umlenkelement-Ebene und Detektions-Ebene

The coordinates y1, z1 describe the plane E1 of the measuring graduation range to be imaged on the scale, the coordinates y2, z2 characterize the plane E2 of the individual lenses on the first side of the lens array, the coordinates y3, z3 describe the plane E3 of the reflecting side of the Deflection element and with y4, z4, the detection level E4 is characterized on the detector. The variable I1 indicates the object distance of the lens array image, ie the distance between the measuring graduation plane E1 and the single lens plane E2 when the imaging beams are reflected at the angle -θ to the normal on the measuring graduation plane E1. The other variables I2 and I3 indicate the distances between the individual lens plane E2 and the deflection element plane E3 or between the deflection element plane E3 and the detection plane E4. The sum of the distances I2 and I3 therefore represents the image distance of the lens array imaging. Due to the given imaging symmetry, the object distance and the image distance of the imaging via the lens array are the same, ie it applies $$\text{I1}=\text{I2}+\text{I3}$$

with:

I1

Object distance of the lens array image (distance between measurement graduation plane and single lens plane)

I2

Distance between single lens level and deflection element level

I3

Distance between deflection element level and detection level

The derivation of relation 1) is briefly explained below.

The well-known equation for optical imaging using a lens with focal length f, object distance g and image distance b is: $$1\text{/ f}=1\text{/G}+1\text{/ b}$$

The imaging scale β associated with an image is defined as follows: $$\text{ß}=\text{b/g}$$

$$\text{b}=\left(1+\text{ß}\right)\cdot \text{f}\text{.}$$

That's where the relationships come from $$\text{G}=\left(1+1/\text{ß}\right)\cdot \text{f}\text{, or}\text{.}$$

$$\text{b}=\left(1+\text{ß}\right)\cdot \text{f}\text{.}$$

Transferred to the conditions in the reflective lens array of the present invention, this means that for the focal lengths f of the individual lenses with a given object distance g and a partial image scale β1 of the reduced image in the lens array, the following relationship results approximately: $$\text{G}=\left(1+1/\mathrm{\beta }1\right)\cdot \text{f}$$

mit:
Da ferner β1 · β2 = 1 gilt, ergibt sich β2 = 1/β1 also $$\text{b}=\left(1+1/\text{ß}1\right)\cdot \text{f}$$

und damit $$\text{b}=\text{g}$$

The following applies to the image width b of the enlarged image with the partial imaging scale β2 $$\text{b}=\left(1+\text{ß}2\right)\text{f}$$

with:
Furthermore, since β1 · β2 = 1, we have β2 = 1/β1 $$\text{b}=\left(1+1/\text{ß}1\right)\cdot \text{f}$$

and thus $$\text{b}=\text{G}$$

so ergibt sich schließlich $$\text{I1}=\text{I2}+\text{I3}$$

If we now replace the quantities b and g with the quantities I1, I2, I3, according to $$\begin{array}{l}\text{G}=\text{I1}\text{, and}\\ \text{b}=\text{I2}+\text{I3}\text{,}\end{array}$$

this is how it finally turns out $$\text{I1}=\text{I2}+\text{I3}$$

mit:

z1

z-Koordinate der Messteilungs-Ebene

z3

z-Koordinate der Umlenkelement-Ebene

z4

z-Koordinate der Detektions-Ebene

Equation 1) results in the following relationship after the representation of I1, I2 and I3 via the coordinates yn, zn (n = 1..4) and a mathematical transformation: $$\text{z3}-\text{z1}=\left(\text{z4}-\text{z1}\right)/2$$

with:

z1

z-coordinate of the graduation plane

z3

z-coordinate of the deflection element plane

z4

z coordinate of the detection plane

The derivation of equation 2) is briefly outlined below

$$\text{I2}=\left(\text{z2}-\text{z3}\right)/\text{cos}\mathrm{\Theta }$$

$$\text{I3}=\left(\text{z4}-\text{z3}\right)/\text{cos}\mathrm{\Theta }$$

Equation 1) can be expressed in the z and y coordinates as follows: $$\text{I1}=\left(\text{z2}-\text{z1}\right)/\text{cos}\mathrm{\theta }$$

$$\text{I2}=\left(\text{z2}-\text{z3}\right)/\text{cos}\mathrm{\theta }$$

$$\text{I3}=\left(\text{z4}-\text{z3}\right)/\text{cos}\mathrm{\theta }$$

With I1 = I2 + I3 we get $$\left(\text{z2}-\text{z1}\right)/\text{cos}\mathrm{\theta }=\left(\text{z2}-\text{z3}\right)/\text{cos}\mathrm{\theta }+\left(\text{z4}-\text{z3}\right)/\text{cos}\mathrm{\theta }$$

Multiplying out the expressions in brackets gives $$\text{z2/cos}\mathrm{\theta }-\text{z1/cos}\mathrm{\theta }=\text{z2/cos}\mathrm{\theta }-\text{z3/cos}\mathrm{\theta }+\text{z4/cos}\mathrm{\theta }-\text{z3/cos}\mathrm{\theta }$$

This can be simplified $$-\text{z1}=-2\cdot \text{z3}+\text{z4}$$

About the addition of +/- z1 results $$2\cdot \text{z3}-2\cdot \text{z1}+\text{z1}=\text{z4}$$

Ultimately it follows $$\left(\text{z3}-\text{z1}\right)=\left(\text{z4}-\text{z1}\right)/2$$

Relation 2) clearly means that the deflection element plane E3 should preferably be arranged exactly in the middle between the measuring graduation surface and the detector surface; or to put it another way: the deflection element is preferably arranged centrally between the measuring graduation plane E1 and the detection plane E4.

In contrast, the position of the plane E2 with the individual lenses on the first side of the lens array, which is given by the coordinates y2, z2, can be selected arbitrarily in the scanning unit; there are no restrictions whatsoever in this regard from equation 2). In the position measuring device according to the invention, the angle θ at which the imaging bundle of rays is reflected by the measuring graduation relative to a normal to the measuring graduation can also be freely selected. Accordingly, there are no restrictive conditions that might stand in the way of a compact construction of the scanning unit in the position-measuring device according to the invention.

A further embodiment of the optical position measuring device according to the invention is finally based on 5 described, with essentially only the relevant differences from the first exemplary embodiment being discussed. It is provided here in the scanning unit 120 that the deflection element 124 is now arranged in the imaging beam path between the scale 110 and the lens array 123 . This means that in the scanning unit 120, the bundles of rays coming from the measuring graduation 111 first strike the reflecting side 124.1 of the deflection element 124, which is also designed as a planar deflection mirror, and are then directed in the direction of the first side 123.1 of the lens array 123 with the individual lenses 123.L reflected. The illuminated measurement graduation area is imaged onto the detector 125 via the lens array, which is designed identically to the previous example.

• I1 := Bildweite der Linsenarray-Abbildung (Distanz zwischen Einzellinsen-Ebene und Detektions-Ebene)
• I2 := Distanz zwischen Einzellinsen-Ebene und Umlenkelement-Ebene
• I3: := Distanz zwischen Umlenkelement-Ebene und Maßstabs-Ebene

In principle, the above-described formulaic relationships of equations 1) and 2) also apply in this example, although the sections I1, I2, I3 are defined differently, according to:

• I1 := image distance of the lens array imaging (distance between single lens plane and detection plane)
• I2 := distance between single lens level and deflection element level
• I3: := distance between deflection element level and scale level

In this example, too, the deflection element 124 or its reflecting side 124.1 is again preferably arranged centrally between the measuring graduation plane and the detection plane.

In the case of such a solution, due to the position of the lens array, provision could also be made for it to be integrated into a cover glass on the underside of the scanning unit 120 .

In addition to the exemplary embodiments explained, there are, of course, other options for alternatively designing the optical position-measuring device according to the invention.

For example, it would be possible to design the areas between the reflective sub-areas on the second side of the lens array to be absorbent. In this way, the penetration or forwarding of stray light can be prevented.

As an alternative to this, on the second side of the lens array the areas between the reflective partial areas could also be reflective, so that a single, continuous reflector is arranged on this side.

Furthermore, it could be provided that diaphragms are introduced into the lens array in the light path between the first and second passage of the individual lenses. In this way, undesirable optical crosstalk between adjacent individual lenses can be avoided and the effects of scattered light can be reduced. Furthermore, in this case the scanning proves to be very robust, in particular with regard to fluctuations in the scanning distance.

Furthermore, instead of the pseudo-random code, a different embodiment of the absolutely coded measuring graduation can also be provided.

It would also be possible for any incremental graduations that may be present on the material measure to be imaged on a suitable detector via the reflective lens array. For this purpose, the same lens array can be used as for imaging the absolutely coded measuring graduation.

As an alternative to the explained one-dimensional arrangement of cylindrical lenses on the first side of the lens array, provision can also be made for a two-dimensional arrangement of individual lenses to be formed on the first side of the lens array. Accordingly, a two-dimensional arrangement of corresponding reflectors is then to be provided on the opposite, second side, etc.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 10317736 A1 [0002]
• JP 2015081794 A2 [0003]

Claims (13)

Optical position measuring device for determining the position of a first object, which can be moved relative to a second object along a measuring direction, with - a material measure connected to the first object with a measuring graduation extending along the measuring direction, and - a scanning unit which is connected to the second object is connected, with - at least one light source, - a detector, and - a lens array for imaging a measurement graduation range onto the detector, characterized in that the lens array (23; 123) has a plurality of adjacently arranged has individual lenses (23.L; 123.L) and on an opposite, second side (23.2; 123.2) a plurality of reflectors (23.R; 123.R) are arranged at least in partial areas, with the individual lenses (23.L; 123 .L) a reduced image of the measurement graduation range (11 _MB ) in an intermediate image (23 _ZB ) on the reflectors (23.R; 123.R) and then the intermediate image (23 _ZB ) is an enlarged image on the individual lenses (23.L ; 123.L) into an image of the measurement graduation area (25 _B ) on the detector (25; 125). Optical position measuring device claim 1 , characterized in that the lens array (23; 123) is used to image the measurement graduation area onto the detector (25; 125) with the imaging scale β _tot = 1. Optical position measuring device claim 1 , characterized in that each individual lens (23.L; 123.L) on the second side (23.2; 123.2) of the lens array (23; 123) is assigned at least one reflector (23.R; 123.R). Optical position measuring device claim 3 , characterized in that each reflector (23.R; 123.R) is arranged on the second side (23.2; 123.2) in the course of the imaging beam path centered on the middle of the associated individual lens (23.L; 123.L) and has a surface , which is dependent on the partial image scale β1 of the reduction image. Optical position measuring device claim 1 , characterized in that on the second side of the lens array the areas between the partial areas with the reflectors are also designed to be reflective, so that a continuous reflector is arranged there. Optical position measuring device according to at least one of Claims 1 - 5 , characterized in that a deflection element (24) is arranged in the imaging beam path between the lens array (23) and the detector (25), which deflects the imaging beam bundles coming from the lens array (23) in the direction of the detector (25), the first Side (23.1) of the lens array (23) faces the deflection element (24). Optical position measuring device claim 6 , characterized in that the deflection element (24) is designed as a deflection mirror, whose reflecting side (24.1) is acted upon by the imaging beams. Optical position measuring device claim 7 , characterized in that the first side (23.1) of the lens array (23) faces the reflecting side (24.1) of the deflection mirror (24). Optical position measuring device according to at least one of Claims 6 - 8th , characterized in that the deflection element (24) is arranged centrally between the measurement graduation plane (E1) and the detection plane (E4). Optical position measuring device according to at least one of Claims 1 - 5 , characterized in that a deflection element (124) is arranged between the material measure (110) and the lens array (123), which deflects the beams coming from the measuring graduation (111) in the direction of the lens array (123). Optical position measuring device claim 10 , characterized in that - the deflection element (124) is designed as a deflection mirror, the reflective side (124.1) of the beams of rays coming from the measuring graduation (111) are applied, and - the first side (123.1) of the lens array (123) is oriented in the direction of the detector (125), and - the deflection element (124) is centered between the measuring graduation plane and the detection -level is arranged. Optical position measuring device according to at least one of the preceding claims, characterized in that the measuring graduation (11; 111) is designed as a reflection measuring graduation which has graduation areas (11a, 11b) with different reflection properties arranged alternately along the measuring direction (x). Optical position measuring device according to at least one of the preceding claims, characterized in that the measuring graduation (11; 111) is designed as an absolutely coded measuring graduation.

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