DE102009025324B4 - Method and detection device with a contact image sensor for detecting spatial structures - Google Patents

Abstract

Detection device (1) comprising a contact surface (2), relative to which an object to be detected can be arranged, a contact image sensor (5) arranged adjacent to the contact surface (2) for detecting the object arranged relative to the contact surface (2), wherein the Contact image sensor (5) comprises a plurality of pixel detection units (6, 6-1, ..., 6-6), each of which has an imaging unit (7, 7-1, ..., 7-6) and at least one pixel detection unit (8, 8-1, ..., 8-6), the imaging units (7, 7-1, ..., 7-6) each having sections of the relative to the contact surface (2), preferably in contact with the contact surface (2), map the arranged object onto the respective at least one assigned pixel detection unit (8, 8-1, ..., 8-6), the pixel detection units (8, 8-1, ..., 8-6) convert incident imaged electromagnetic radiation into electrical signals, whereby by means of the image point detection units (6, 6-1, ..., 6-6) sharply imaged Bi Id points of at least two planes (18, 19) of the object which are at a different distance from the contact surface (2) can be detected or are detected, characterized in that the different pixel detection units (6, 6-1, ..., 6-6), which capture the sharp image points of the different planes (18, 19) of the object, have imaging units (7, 7-1, ..., 7-6) with different imaging properties, in particular different focal lengths.

Description

The invention relates to a method and a detection device for detecting spatial structures of an object. In particular, the invention relates to a detection device which comprises a contact surface, relative to which an object to be detected can be arranged, a contact image sensor arranged adjacent to the contact surface for detecting the object arranged relative to the contact surface, the contact image sensor having a plurality of pixel detection units each comprising an imaging unit and at least one pixel detection unit, the imaging units each imaging sections of the object arranged relative to the contact surface, preferably in contact with the contact surface, onto the respective at least one assigned pixel detection unit, the pixel detection units converting incident imaged electromagnetic radiation into electrical Convert signals. With such a detection device, it is possible to optically detect an object which is arranged relative to the contact surface, preferably in contact with the contact surface. The electromagnetic radiation shown is converted into electrical signals that represent a measure of the received light intensity.

Such detection devices and such methods for detecting an object are used, for example, in scanners. A large number of scanners for detecting objects, for example paper documents, are known in the prior art. In addition, scanners are used for various tasks in the field of security technology. For example, scanners in the field of verification of value and / or security documents are known, which are used for the automatic acquisition of information from the value and / or security document in order to subsequently carry out a verification of the acquired information. In particular, security features and security elements of the corresponding value and / or security document are recorded and evaluated.

From the US 5,627,366 A1 a bar code scanner is known which has several cylindrical lenses with different focal lengths, each of which image the bar code pattern on an imaging solid-state detector assigned to the respective lens, in particular a CCD sensor line (Charge Coupled Device line). The signals detected with the aid of the CCD sensor lines are fed to a comparison device in order to select the signal with the best contrast from the signals detected via the different lenses and to use it for decoding the bar code pattern.

From the DE 103 49 611 A1 systems and methods for optical scanning of several object planes are known which are required in order to also be able to optimally detect text parts in a section of a book page that is curved to form a book cover groove. A described embodiment is a method for providing multiple object planes in an optical image scanning environment that includes positioning and positioning a first optical sensor array to receive an optical signal corresponding to a first object plane located a first distance from the support a second optical sensor array to receive an optical signal corresponding to a second object plane located a second distance from the support.

A document is referred to as a value and / or security document which has at least one so-called security feature or security element. Security features are those features that make it difficult and / or impossible to imitate, falsify and / or copy the value and / or security document. A structural unit which comprises or represents at least one security feature is referred to as a security element.

Valuable and / or security elements include, for example, passports, identification cards, identity cards, driver's licenses, vehicle registration documents, tax codes, postage stamps, credit cards, banknotes, securities, etc. In the field of security technology, scanners are also used, for example, to record biometric data, such as papillary line patterns. The pattern of papillary lines on a person's fingers is unique to each person. This means that identification via pattern recognition of the papillary lines is possible with very high reliability.

However, it is known that a person's papillary line pattern can be recreated. For this purpose, for example, a plastic coating can be applied to a finger-like dead object or a living finger of another person. In order to enable a distinction between papillary line patterns of a living person and a forged papillary line pattern, it is known from the prior art not only to acquire information about the surface on which the papillary line pattern can be optically detected, but also from the "depth" of the finger. From the WO 98/35118 A1 For example, an identification device is known which has a unit for detecting biometric features and a unit for detecting the vitality of a person. Only when it has been recognized that the person who is to be identified is actually alive are those recorded Biometric features compared with stored person-specific features in order to carry out an identification. In order to detect the biometric signals, it is proposed, for example, to transmit and receive electromagnetic signals or acoustic signals. With electromagnetic signals in the optical range, preferably in the infrared wavelength range, it is proposed to record an external fingerprint, ie the papillary lines on the surface. By means of the transmission and reception of acoustic signals, it is described how to record both the external fingerprint and an internal fingerprint (an epidermis inside the finger). In order to determine the vitality of the finger, further sensors, for example a pulse detection unit, are provided.

In general, there is a need to create ever new and more complex security features for security documents and, on the other hand, to create more sophisticated detection devices and methods to securely detect complex security features and / or biometric features and thereby forgeries or. Reliably detect falsification of security features or biometric features. In addition, the detection devices and methods should be simple and inexpensive to implement and the detection devices should be sufficiently robust to be able to be used in portable units.

One possibility of creating complex security features is to use spatial structures as security features. In value and / or security documents, different information can be stored about this in different levels of the document, which for example represent information distributed over an area for a human observer. For example, the pixels of a face image can be stored in different layers of the document. This means that the individual pixels of the face image are stored in different layers of the document. If only transparent layers are arranged above the image points, then the facial image can be perceived as a whole by a viewer. Only with a precise analysis can it be determined that individual pixels are arranged in different planes.

When detecting papillary line patterns, spatial detection, i.e. detection in different planes of the object, it can be achieved that only superficially formed papillary line patterns can be distinguished from papillary line patterns of living fingers, since in these the papillary line pattern has a greater spatial depth.

The invention is therefore based on the technical problem of creating a detection device and a method with which spatial structures can be detected optically.

The invention is based on the basic idea of using a contact image sensor (CIS) for capturing image points. Such a contact image sensor comprises a plurality of image point detection units. The pixel detection units each include an imaging unit which images a section of an object onto a pixel detection unit. The pixel detection unit converts the imaged electromagnetic radiation into an electrical signal. This is proportional to the mapped intensity of the electromagnetic radiation. The contact image sensor is modified compared to the contact image sensors known from the prior art in such a way that by means of the image point detection units sharply mapped image points of at least two planes of the object having a different distance to a contact surface relative to which the contact image sensor is arranged are or will be recorded. A method for capturing image points of an object with a contact image sensor which is arranged relative to the contact area and comprises a plurality of image point detection units, each comprising an imaging unit and at least one pixel detection unit, thus comprises the steps of: arranging the object relative to the contact area Acquisition of pixels of the object, the imaging units each imaging sections of the object arranged relative to the contact surface, preferably in contact with the contact surface, onto the respective at least one assigned pixel detection unit and the pixel detection units converting the imaged electromagnetic radiation into electrical signals that provide a measure represent for a received light intensity. It is provided here that sharply mapped image points of at least two planes of the object that have a different distance from the contact surface are captured by means of the image point acquisition units. If an image point of the object is sharply imaged on a pixel detection unit, a maximum intensity of the diffracted or scattered radiation reflected at the image point of the object is imaged on the pixel detection unit. It is assumed here that an image point is light (for example white) against a dark background (for example black). If an image point is imaged in another plane, its image is expanded in the pixel detection plane so that part of the light intensity is not detected.

A pixel is referred to as sharply imaged if the pixel captured by it together with further pixels from other pixels of a structure contributes to a resolved and high-contrast image of the structure. This means that the light originating from a section of the object in the relevant plane is bundled (in the case of a bright image point), that is to say is imaged in a focused manner. This is used for selective mapping with regard to a distance from the contact image sensor. The image points are recorded in such a way that the recorded pixels reflect information content of a specific level.

An active area of the pixel detection unit is therefore preferably selected to be adapted to a minimum size of a sharply imaged image point of the object of a respective imaging unit of an image point detection unit. In addition to the focal length, the choice of a diaphragm on the exit side of the imaging unit also has an influence on this.

The advantage of the device according to the invention and the method according to the invention is that information from different levels can be or is recorded and can be used to verify complex, spatially developed security features or biometric features.

According to the invention it is provided that the different image point acquisition units, which acquire the sharply imaged image points of the different planes of the object, have imaging units with different imaging properties, in particular with different focal lengths. If, for example, image points on two different levels are to be acquired, there are two different types of image point acquisition units which simultaneously acquire the image points of the different levels. These different types of pixel acquisition units each have different imaging units which have different imaging properties. One type of image point detection units has, for example, imaging units with a first focal length and the other type of image point detection units has imaging units with a different focal length that deviates from the first focal length.

In order to facilitate calibration of the individual pixel detection units, the image contact sensor is preferably designed such that a pixel density of the pixel detection units is greater than a pixel density in the object, i.e. H. as a minimum feature size to be captured. This means that the structures of the object to be recorded each have a lateral extent in a plane, which is mapped onto two recorded image pixels by at least two adjacent image point detection units.

The at least two different planes are advantageously detected by means of image point detection units which are arranged uniformly alternately and which have imaging units with different imaging properties. If the structures containing the information, which are to be recorded and evaluated, each have extensions laterally in the planes, which are mapped by several neighboring recorded pixels, then a clear signal difference between neighboring pixels can be recorded. In each case, only one of two adjacent pixel detection units images the corresponding structure of the object sharply, if it is assumed that information in the form of a structure formed laterally in the plane is only formed in one plane of the object.

In order to achieve a good separation of the individual planes of the object, it is advantageous if the individual imaging units of the image point acquisition units each have a small depth of field. On the one hand, this can be achieved by designing the imaging units with the largest possible numerical aperture.

In a preferred embodiment, the imaging units comprise rod lenses. With these, the desired imaging properties can be implemented particularly favorably.

To get a good resolution i.e. Assignment of the captured information to the individual planes that are captured is provided in a preferred embodiment that the focal lengths of the imaging units of the pixel capture units when capturing the sharply mapped pixels of the different planes differ by at least a value that is of the order of magnitude of a value of a maximum length of the depth of field areas that the imaging units correspondingly have when capturing the image points.

In order to achieve a resolution in the range of 100 µm, a depth of field less than 100 µm should be selected. For this purpose, on the one hand, the numerical aperture of the imaging unit must be selected as large as possible. On the other hand, an active area of the pixel size should be selected as small as possible. Preferred embodiments therefore have a diameter of an active area of the pixel detection units in the order of magnitude of the wavelength of the electromagnetic radiation that is converted. If, for example, green light is used, which has a wavelength in the range of 550 nm, then active areas of the pixel detection units of the order of magnitude of 1 μm are desirable.

In order to be independent of chromatic aberration, it is provided in a preferred embodiment that one or more luminous elements are arranged relative to the contact surface in order to illuminate the object to be detected monochromatically. In some embodiments, several different illuminants are provided which generate light of different wavelengths, for example in the infrared wavelength range in the visible and in the ultraviolet wavelength range. The different illuminants can be controlled in such a way that the object is illuminated monochromatically with one of the wavelengths. In order to obtain uniform illumination, there are preferably a plurality of illuminants that generate light of the same wavelength.

In order to achieve a high degree of flexibility, it is provided in a preferred embodiment that at least some of the plurality of pixel acquisition units comprise imaging units which can be modified in a controlled manner with regard to their imaging properties.

In a development in which the imaging units include lenses, preferably rod lenses, it is provided that the lenses of the imaging units of the part of the plurality of image point detection units, which can be modified in a controlled manner with regard to their imaging properties, are designed to be deformable and jointly, in groups or individually with one Actuator are coupled, via which a deformation of all lenses of the group of lenses or of the individual lenses can be brought about in order to modify the optical properties. Piezocrystals, for example, can be arranged as actuators adjacent to the lenses in order, for example, to stretch the lenses. Other embodiments provide that a radius of curvature of the exit surface of the lenses is modified via compression or elongation in order to achieve a focal length modification.

An evaluation unit, which is designed to determine whether and which information embodied by the captured image points is stored in the different planes of the object, is preferably coupled to the contact image sensor. The object that is detected can be, for example, a finger or a value and / or security document.

The features of the method according to the invention have the same advantages as the corresponding features of the detection device.

• 1 eine schematische Darstellung einer als Dokumentenscanner ausgebildeten Erfassungsvorrichtung;
• 2 eine schematische Darstellung einer weiteren Ausführungsform, bei der einzelne Bildpunkterfassungseinheiten modifizierbare Abbildungseinheiten umfassen;
• 3 eine weitere Ausführungsform mit modifizierbaren Abbildungseinheiten; und
• 4 eine Draufsicht auf eine weitere Ausführungsform modifizierbarer Abbildungseinheiten.

The invention is explained in more detail below on the basis of preferred exemplary embodiments. Here show:

• 1 a schematic representation of a detection device designed as a document scanner;
• 2 a schematic representation of a further embodiment, in which individual image point acquisition units comprise modifiable imaging units;
• 3 a further embodiment with modifiable imaging units; and
• 4th a plan view of a further embodiment of modifiable imaging units.

In 1 is schematically a detection device 1 shown. The detection device 1 is designed as a document scanner. The detection device 1 includes a transparent contact surface 2 . The transparent contact surface 2 is designed here as a support plate. This includes a housing 3 to a top 4th down. In the case 3 , adjacent to the contact surface 2 , is a contact image sensor 5 arranged. The contact image sensor 5 comprises individual pixel acquisition units 6th .

In the figures, a number provided with a hyphen is appended to the reference symbol “6” to indicate the individual pixel detection units 6th to distinguish. When reference is made to all image point detection units, the reference symbol “6” is used without a number after it. The procedure is analogous to other characteristics and entities that occur more than once.

Each pixel acquisition unit 6th comprises an imaging unit 7th and a pixel detection unit 8th . The imaging units 7th are designed as rod lenses in the illustrated embodiment. Each pixel acquisition unit 6th forms a section 9 of a document 10 from. Here is the document 10 with its front 11 arranged in contact with the contact surface. The imaging units 7th of the individual pixel acquisition units 6th each form one of the sections 9 on the assigned pixel detection unit 8th from. The pixel detection units 8th convert the received, imaged electromagnetic radiation into an electrical signal.

The pixel detection units 8th are on a common substrate 12 , preferably by means of CMOS technology. The converted signals from the pixel detection units 8th are connected to a control unit 13 forwarded. This usually includes an evaluation unit 14th that evaluates the received electrical signals. To the document 10 to illuminate are one or more lamps 15th intended. These generate monochromatic radiation that covers the document 10 from its front 11 that are in contact with the contact surface 2 is to illuminate. The lighting can take place both in the visible wavelength range and in the ultraviolet or infrared wavelength range. It is also possible for the excitation to take place with a wavelength that deviates from the wavelength generated by the contact image sensor 5 is proven. This is advantageous when the structures to be detected 16 , 17th , about the information in the document 10 are coded, are designed as luminescent structures. Some embodiments have different illuminants so that a specific wavelength can be selected for the illumination.

The structures 16 , 17th are in different levels 18th , 19th arranged at a different distance from the front 11 of the document 10 and thus to the contact surface 2 exhibit.

The imaging units 7th of the individual pixel acquisition units 6th are trained differently. The imaging units embodied as rod lenses in this exemplary embodiment have alternating 7th a different focal length. This means that the imaging units 7th have alternately changing imaging properties. The imaging units 6-1 , 6-3 , 6-5 , the rod lenses of which are shown longer in the schematic representation, are designed so that they have image points or a structure 16 the level 18th keen on the pixel detection units 8-1 , 8-3 , 8-5 depict. The abbreviated representation units 6-2 , 6-4 , 6-6 however, are designed so that they have pixels or a structure 17th the level 19th keen on the pixel detection units 8-2 , 8-4 , 8-6 depict. A depth of field of the imaging units 7th is chosen so that it is less than a distance between the two levels 18th , 19th from each other.

The pixel acquisition units 6-1 to 6-3 form the structure in the example shown 16 starting that in the plane 18th is arranged. Here are the sections 9-1 to 9-3 accordingly from the pixel acquisition units 6-1 to 6-3 mapped and recorded. The imaging units 7-1 and 7-3 form in each case those in the sections 9-1 and 9-3 lying parts of the structure 16 keen on the pixel detection units 8-1 and 8-3 from. In this context, sharp means that the light captured by the respective section is bundled onto the active surface of the respective pixel detection unit 8-1 or. 8-3 is focused. The image point acquisition unit 6-2 however, has an imaging unit designed as a microlens 7-2 on that for a sharp, ie focused image of light from the plane 19th is trained. The one in section 9-2 lying portion of the structure 16 thus does not become sharp, ie not focused on the pixel detection unit 8-2 pictured. Rather, the light cone passing through the lens is in the area of a detection plane 20th , in which the pixel detection units 8th located, expanded. Thus, between the pixels associated with the pixel detection units 8-1 and 8-3 are detected, and the pixel, which with the pixel detection unit 8-2 is detected, a clear contrast can be seen. It must be taken into account here that an active area of the pixel detection units 8th is selected adapted to a focus size in the area of which the light of an image point of the corresponding intended plane, which is imaged in focus, is collected

The same applies to the pixel acquisition units 6-4 to 6-6 . The pixel acquisition units 6-4 and 6-6 are for capturing image points in the plane 19th formed, which is closer to the contact surface than the plane 18th of the document 10 . The pixel acquisition unit 6-5 on the other hand, is designed around image points of the plane 18th sharply focused on the corresponding pixel detection unit 8-5 map. For those in the field of sections 9-4 to 9-6 lying parts of the structure 19th it is now true that this is from the pixel acquisition units 6-4 and 6-6 sharp on the corresponding pixel detection units 8-4 and 8-6 be mapped. In contrast, the proportion of structure 17th in the section 9-5 not focused on the corresponding pixel detection unit 8-5 pictured. A contrast difference can thus be detected again. This makes it possible to decide whether the structure being recorded 16 , 17th in the plane 18th or the level 19th lies.

It turns out that it is advantageous to choose the captured pixel resolution so that each structural unit is mapped by at least two pixels, preferably 3 pixels, in order to avoid possible edge errors, i.e. better processing a non-optimal alignment of the structure with respect to the captured pixels. However, embodiments are also possible in which structures up to a 1: 1 assignment image point: captured pixel are possible. In this case, however, a good calibration is necessary in order to be able to reliably determine the plane from which electromagnetic radiation is detected.

The contact image sensor can be designed in the form of lines or a matrix. At the in 1 The embodiment shown is the contact image sensor 5 assumed to be linear. Via the scan actuator 21st can the contact image sensor 5 can be moved perpendicular to the drawing plane to the document 10 to capture flat.

Via an interface 29 can the control unit 13 Exchange information, for example evaluation results, with other devices. The interface can for example be designed as a network interface.

In 2 a further embodiment of a detection device is shown. The same technical features are provided with the same reference symbols. In an upper section is a plan view of the line-shaped contact image sensor 5 ' shown. A schematic side view is shown in the lower section. In contrast to the embodiment according to 1 is in the embodiment according to 2 alternating every second imaging unit 7-1 , 7-3 , 7-5 designed to be modifiable. The individual imaging units designed as rod lenses 7-1 , 7-3 , 7-5 are with a mechanism 22nd connected via a lens actuator 23 are jointly deformable in terms of their length. This creates a focal length of the corresponding imaging unit 7-1 , 7-3 , 7-5 modified. In this arrangement, for example, the length of the imaging units is not modifiable 7-2 , 7-4 and 7-6 designed in such a way that the pixels in a plane of a contact surface (not shown) are sharply focused on the corresponding pixel detection units 8-2 , 8-4 , 8-6 depict. By modifying the lengths of the rod lenses of the imaging units 7-1 , 7-3 , 7-5 a distance between the plane and the contact surface which is to be detected can be varied. This creates greater flexibility, since documents of different structures can be recorded and evaluated with the same recording device, in which the individual structures arranged in different planes have different distances from the contact surface.

3 shows a modification of the device according to 2 . In this embodiment, all are imaging units 7-1 to 7-6 variably executed. The imaging properties can be modified in groups. The imaging properties of the rod lenses of the imaging units 7-1 , 7-3 , 7-5 can as in the embodiment according to 2 be modified jointly with regard to their length. In the embodiment according to 3 However, the imaging units 7-2-, 7-4, 7-6, which are also designed as rod lenses, have a further mechanism 23 and another modification factor 24 coupled.

In this embodiment, the imaging units 7th both groups of pixel acquisition units 6th be modified with regard to their imaging properties. In this embodiment, two planes having a freely selectable distance to a contact surface can be detected. In the embodiment according to 3 it is also possible to acquire the same sections of the document one after the other with different imaging properties of the two groups of image point acquisition units. In addition to a lateral variation of the signal, a variation over time due to a change in the imaging property of the associated imaging unit of a respective pixel can also be evaluated. It is particularly advantageous for the groups of imaging units to be set in such a way that they each alternately depict the corresponding planes one after the other. For example, the image point acquisition units form at one point in time 6-1 , 6-3 , 6-5 a first level and the pixel acquisition units 6-2 , 6-4 , 6-6 a second level. At a subsequent point in time, the imaging units are modified in such a way that the image point acquisition units are now 6-1 , 6-3 , 6-5 the second level and the pixel acquisition units 6-2 , 6-4 , 6-6 capture the first level.

It goes without saying for a person skilled in the art that an extension of the rod lenses represents only one possible modification of the imaging properties. Figure 4 is a schematic plan view of another type of imaging unit 7-1 to 7-4 pictured. A plan view of cylinder-shaped lens elements is shown 26th . Adjacent to the lens elements 26-1 to 26-4 are piezo elements 27-1 to 27-4 arranged. The lens elements 26-1 to 26-4 are individually compressed, thereby increasing the radii of curvature of the lens elements 26th let vary. This is exemplified in a lower area for a lens element 26-1 shown schematically. While the lens element at the bottom left 26-1 is shown undeformed, the lens element is at the bottom right 26-1 through the piezo elements 27-1 shown compressed so that a radius of curvature 28 is changed. This changes the imaging properties, so that another plane of an object is in focus relative to the lens element 26-1 arranged pixel detection unit is imaged.

Embodiments with line-shaped image contact sensors are described. Other embodiments may include matrix type image contact sensors.

It is understood by those skilled in the art that only exemplary embodiments are described schematically. The dimensions shown do not correspond to the real dimensions, but are merely selected for the purpose of illustration.

List of reference symbols

1

Detection device

2

Contact area

3

casing

4th

Top (of the case 3 )

5

Contact image sensor

6, 6-1 ... 6-6

Pixel acquisition unit

7, 7-1 ... 7-6

Imaging unit

8, 8-1 ... 8-6

Pixel detection unit

9, 9-1 ... 9-6

section

10

document

11

front

12th

Substrate

13

Control unit

14th

Evaluation unit

15th

Bulbs

16, 17

Structures

18, 19

Layers (of the document / object)

20th

Detection level

21st

Scan actuator

22nd

mechanics

23

Lens actuator

24

further mechanics

25th

further lens actuator

26th

Lens element

27

Piezo element

28

Radius of curvature

29

interface

Claims (21)

Detection device (1) comprising a contact surface (2), relative to which an object to be detected can be arranged, a contact image sensor (5) arranged adjacent to the contact surface (2) for detecting the object arranged relative to the contact surface (2), wherein the contact image sensor (5) comprises a plurality of image point detection units (6, 6-1, ..., 6-6), each of which has an imaging unit (7, 7-1, ..., 7-6) and at least one Pixel detection unit (8, 8-1, ..., 8-6), the imaging units (7, 7-1, ..., 7-6) each having sections of the relative to the contact surface (2), preferably in contact with the contact surface (2) on the respective at least one assigned pixel detection unit (8, 8-1, ..., 8-6), the pixel detection units (8, 8-1, ..., 8-6 ) convert incident imaged electromagnetic radiation into electrical signals, with the image point detection units (6, 6-1, ..., 6-6) being sharply imaged Image points of at least two planes (18, 19) of the object having a different distance from the contact surface (2) can be detected or are detected, characterized in that the different image point detection units (6, 6-1, ..., 6-6) which capture the sharp image points of the different planes (18, 19) of the object, have imaging units (7, 7-1, ..., 7-6) with different imaging properties, in particular different focal lengths. Detection device (1) according to Claim 1 or 2 , characterized in that at least some of the plurality of pixel detection units (6, 6-1, ..., 6-6) comprise imaging units (7, 7-1, ..., 7-6) which are controlled with regard to their imaging properties are modifiable. Detection device (1) according to one of the preceding claims, characterized in that the imaging units (7, 7-1, ..., 7-6) comprise rod lenses. Detection device (1) according to Claim 3 , characterized in that the lenses of the imaging units (7, 7-1, ..., 7-6) of the part of the plurality of pixel detection units (6, 6-1, ..., 6-6) which are controlled with respect to their Imaging properties are modifiable, deformable and are coupled together, in groups or individually to an actuator, via which a deformation of all lenses, the group of lenses or the individual lens can be brought about in order to modify the optical properties. Detection device (1) according to one of the preceding claims, characterized in that the at least two different planes (18, 19), the imaging units (7, 7), by means of alternately arranged pixel detection units (6, 6-1, ..., 6-6) -1, ..., 7-6) with different imaging properties are detectable. Detection device (1) according to one of the preceding claims, characterized in that a diameter of an active area of the pixel detection units (8, 8-1, ..., 8-6) is of the order of magnitude of the wavelength of the electromagnetic radiation that is converted. Detection device (1) according to one of the preceding claims, characterized in that one or more luminous elements are arranged relative to the contact surface (2) in order to illuminate the object to be detected monochromatically. Detection device (1) according to one of the preceding claims, characterized in that that the focal lengths of the imaging units (7, 7-1, ..., 7-6) of the pixel detection units (6, 6-1, ..., 6-6) when capturing the sharply mapped pixels of the different planes are at least one Distinguish value that is of the order of magnitude of a value of a maximum length of the depth of field regions that the imaging units (7, 7-1, ..., 7-6) have when capturing the image points. Detection device (1) according to one of the preceding claims, characterized in that an evaluation unit is provided in order to determine whether and which information embodied by the image points is stored in the different levels of the object. Detection device (1) according to one of the preceding claims, characterized in that the object is a finger or a security document. Method for capturing image points of an object with a contact image sensor (5) which is arranged relative to a contact surface (2) and comprises a plurality of image point acquisition units (6, 6-1, ..., 6-6), each of which an imaging unit (7, 7-1, ..., 7-6) and at least one pixel detection unit (8, 8-1, ..., 8-6), comprising the steps of: arranging the object relative to the contact surface ( 2), capturing image points of the object, the imaging units (7, 7-1, ..., 7-6) each having sections of the object arranged relative to the contact surface (2), preferably in contact with the contact surface (2) onto the respective at least one assigned pixel detection unit (8, 8-1, ..., 8-6) and the pixel detection units (8, 8-1, ..., 8-6) convert the imaged electromagnetic radiation into electrical signals , which represent a measure of a received light intensity, with sharp by means of the pixel detection units (6, 6-1, ..., 6-6) imaged image points of at least two planes (18, 19) of the object having a different distance from the contact surface (2) are detected, characterized in that the sharply imaged image points of the at least two different planes (18, 19) of the object are detected by means of the image point detection units (6, 6-1, ..., 6-6), whose imaging units (7, 7-1, ..., 7-6) have different imaging properties, in particular different focal lengths. Procedure according to Claim 11 characterized in that the imaging units (7, 7-1, ..., 7-6) are modified in a controlled manner with regard to their imaging properties for at least some of the plurality of pixel detection units (6, 6-1, ..., 6-6) in order to create different imaging properties for the detection of the image points of the different planes (18, 19) of the object. Method according to one of the Claims 11 or 12 , characterized in that the sections of the object are imaged by means of rod lenses. Procedure according to Claim 13 , characterized in that the rod lenses of the imaging units (7, 7-1, ..., 7-6) of the part of the plurality of pixel detection units (6, 6-1, ..., 6-6) that are controlled with respect to their Imaging properties are modified, are deformed. Method according to one of the Claims 11 to 14th , characterized in that the image points of the at least two different planes (18, 19) are recorded alternately with respect to a lateral extent of the contact image sensor (5). Method according to one of the Claims 11 to 15th , characterized in that the image points of the at least two planes (18, 19) are detected offset in time. Method according to one of the Claims 11 to 16 , characterized in that the object is illuminated with monochromatic electromagnetic radiation. Method according to one of the Claims 11 to 17th , characterized in that the sharply mapped image points of the different planes are captured with focal lengths of the imaging units (7, 7-1, ..., 7-6) of the pixel acquisition units (6, 6-1, ..., 6-6) which differ by at least a value that is of the order of magnitude of a value of a maximum length of the depth of field regions that the imaging units (7, 7-1, ..., 7-6) have when detecting the image points. Method according to one of the Claims 11 to 18th , characterized in that the captured image points are evaluated in order to determine whether and which information embodied by the image points is stored in the different levels of the object. Method according to one of the Claims 11 to 19th , characterized in that papillary lines are detected in at least two levels of a finger and evaluated with regard to the equality of the patterns. Method according to one of the Claims 11 to 20th , characterized in that information from at least two levels of a value and / or Security document are read and evaluated in order to carry out a verification.

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