WO2011128373A1

WO2011128373A1 - Optical scanner

Info

Publication number: WO2011128373A1
Application number: PCT/EP2011/055820
Authority: WO
Inventors: Markus Gerigk; Andreas BÄCKER; Simon Vougioukas; Thomas Birsztejn; Christian Roth; Stephan Tabaschuss; Walter Speth; Ralf IMHÄUSER; Ludger BRÜLL
Original assignee: Bayer Technology Services Gmbh
Priority date: 2010-04-14
Filing date: 2011-04-13
Publication date: 2011-10-20
Also published as: EP2558926A1; DE102010015014A1

Abstract

The invention relates to the technical field of detecting characteristic features of the surface of an object. The subject matter of the present invention is a device and a method for optically detecting characteristic surface features with the aid of a handheld device. For this purpose, a surface sensor (12) and a navigation sensor (11) are used.

Description

Optical scanner

The invention relates to the technical field of detecting characteristic features of an object surface. The subject of the present invention is an apparatus and a method for the optical detection of characteristic surface features with the aid of a hand-held device.

The surface quality of objects plays an important role in many technical products and processes, for example in mold making and in technical sliding or visible surfaces. For paper, the surface texture is an important quality feature, e.g. in the context of printability.

Accordingly, there are a variety of measurement methods for determining the surface structure and for determining characteristic characteristics for the surface condition. An example of a measurement method for determining the topography of an object surface is dynamic laser focusing (see, for example, Wochenblatt für Papierfabrikation, ISSN0043-7131, Volume 117, April 1989, No. 7, pages 271 to 274). Here, a laser is focused by means of a lens on the surface. The lens can be moved by means of a servomotor perpendicular to the surface (in the z-direction). A sensor detects the respective z-position of the lens in a focused position and thus provides the topography information while the sample is moved horizontally through an xy-table under the lens. It is also known that one can identify and authenticate objects based on the unique intrinsic structure of their surface.

In WO05 / 088533A1, for example, a method is described in which a surface area of an object is scanned with coherent radiation and by means of photodetectors the differently scattered rays at different points of the surface at different angles are detected. The detected scattered radiation is characteristic of a variety of different materials and is very difficult to mimic, as it is due to random manufacturing. For example, paper-like objects have a manufacturing fiber structure that is unique to each manufactured object. The scatter data to the individual objects can be stored as a characteristic fingerprint of the object in a database to the object at a later Identify time and / or to be able to authenticate. For this purpose, the object is measured again and compared the scatter data with the stored fingerprint.

The GB2097979A disclosure describes a method of identifying objects based on surface features. The surface features are detected in a selected surface area of the object to be identified. For this purpose, "meaningful, random singularities of the profile are counted in the form of bumps and measured their heights and distances".

The disclosure WO2000 / 65541 A discloses a method and a device for authenticating an object on the basis of intrinsic physical features, in particular on the basis of topographical information.

The disclosure WO2003 / 087991A2 discloses a method and an apparatus for authenticating objects based on the three-dimensional surface structure.

All of the above methods have in common that characteristic features of an object surface are detected. In this case, a part of the object surface is always scanned by means of a scanning device and the resulting signals are detected with a detector in a location-dependent manner, ie. there is a correlation between the location of the surface and the sampling signal originating from this location. The unit of scanner and detector is also referred to herein as a surface sensor. Usually, however, the scanning signal is not detected directly as a function of the location. Rather, the sampling of the location and the acquisition of the resulting signal at a constant measurement frequency is a function of time, while the surface sensor is moved at a constant rate relative to the object surface. About the known speed exists a known relationship between measurement time and location of the scan, so that the detected intensity-time signal can be converted into an intensity-location signal.

However, if the speed at which the surface sensor moves in relation to the surface of the object is not known, such a correlation is not possible. In such a case, it is customary to determine separately from the sampling signal as a function of time (measurement frequency) an additional signal that links the time (measurement frequency) to the location. This is usually done by means of so-called mechanical, optical or magnetic encoder. By means of such an encoder, the intensity-time signal can be converted into an intensity-location signal.

For example, in the case of the method described in WO05 / 088533A1, markers with a constant pitch of 300 microns are used to transform the intensity-time signal into an intensity-location signal (see WO05 / 088533A1 page 23). These markers are optically detected with a separate photodetector. Since the constant measuring frequency (sampling rate) and the distance of the markings are known, the location at which the focused scanning beam was located can be determined at any time.

The method described in WO05 / 088533A1 has the disadvantage that markings must be applied to the surface. There are objects where it is not possible or not desired to apply markings to the surface.

In the methods described above, the scanning of an object surface is by means of a device that moves in machine relation to the object surface. The mechanical movement takes place for example by means of a servomotor. In order to make a scan, the object must be positioned opposite the device. For ease of positioning, positioning aids such as the stop edges may be used with the reference numeral 42 in Fig. 4 of WO05 / 088533A1. However, such a solution is not very flexible. Different objects may have to be positioned differently with respect to the device, so that different positioning aids may need to be provided for different objects.

It would be desirable to be able to scan the surface of different objects in a simple manner.

Based on the known state of the art, the technical problem therefore arises of providing a method for scanning an object and recording a scanning signal, which manages without special markings on the object and can be used flexibly with respect to different objects.

Surprisingly, it has been found that characteristic features of object surfaces can be obtained in a simple, flexible and reproducible manner with a hand-held device in which the sensor for detecting the characteristic features is integrated in a computer mouse. Computer mice are known and widespread as a machine-human interface. The movement of a computer mouse on the table or a special pad (mouse pad) is recorded via a sensor in the mouse, digitized and transmitted via an interface to a connected computer. Functions of the operating system convert the two-dimensional movement of the mouse into a similar movement of a mouse pointer on a screen.

The computer mouse is thus a device for detecting translational movements. In addition, it is intuitive to use and known to many people from everyday life.

By combining a device for detecting characteristic features of an object surface and a computer mouse, a simple and intuitive to use, flexible hand-held device is created, with which an object surface can be scanned manually. In contrast to a machine scan, a manual scan can not guarantee a constant scan speed. Therefore, the mouse functions to detect the movement of the handset.

The subject of the present invention is therefore a hand-held device for detecting characteristic features of an object surface which can be guided manually over the object surface, comprising at least a surface sensor for detecting characteristic features of an object surface, a navigation sensor for detecting movements of the hand-held device on the object surface. Another object of the present invention is a method for detecting characteristic features of an object surface. The method is characterized in that a hand-held device is manually guided over the object surface and the surface is scanned by means of a surface sensor and an intensity-time signal is generated, wherein the movement of the handheld device is detected by means of a navigation sensor and a navigation signal is generated, and the intensity Time signal is converted by the navigation signal into an intensity-location signal.

The hand-held device according to the invention thus combines two different sensors: a surface sensor for detecting characteristic features of the surface and a navigation sensor for detecting the movements of the hand-held device on the object surface.

By means of the surface sensor, a region of the object surface is scanned, ie measurement signals are recorded as a function of time, which result from a characteristic response of the Object surface result on an external stimulus. The external stimulus may be, for example, an incident light beam that is reflected in a characteristic manner by the object surface. The reflected beam is detected by means of a suitable sensor. The result of the sampling is thus a signal intensity as a function of time. By means of the navigation sensor takes place - at the same time as the scanning of the object surface with the surface sensor - the detection of the movement of the handset in relation to the object surface. The result is a navigation signal. Usually, the navigation signal reflects the speed (direction and magnitude) of the handset as a function of time.

By means of the navigation signal, it is possible to convert the intensity-time signal of the surface sensor into a time-independent intensity-location signal.

As a navigation sensor is in principle any known from today's ubiquitous computer mice sensor for detecting the movement of the computer mouse. Suitable sensors can be found, for example, in the book by Klaus Dembowski: PC Hardware Reference: Information on the entire hardware in quick access. 10th edition. Markt & Technik Verlag, Munich 2000, ISBN 3-8272-5606-2, pp 472-480 (chapter "mouse").

Preferably, an optical navigation sensor is used. This has a light source for illuminating a portion of the object surface, thereby producing reflected images, a detector for generating digital images based on the reflected images, and means for performing motion calculation based on the digital images to obtain motion data indicative of relative motion specify the navigation sensor and the object surface.

Optical navigation sensors are described, for example, in US4799055, US6967321B2, US7002549B2, US6927759B2, WO94 / 011845A1, US6256016B1, EP942286A1.

As already stated, characteristic surface features of an object are detected by means of the surface sensor. These features can be used, for example, to identify or authenticate the object. They are therefore also referred to below as identification features. An identifying feature is virtually a fingerprint of an item.

Identification is understood as a process that serves to uniquely recognize an object. Authentication is the process of verifying (verifying) an alleged identity. The authentication of objects is the statement that they are authentic - that is, they are unchanged, not copied and / or not faked originals.

An object is understood to mean any solid body. The surface of the object separates it from the surrounding medium (mostly air).

If the characteristic surface features are used for identification or authentication, they are preferably those features which have a random character. This means that the features are introduced into the object due to, for example, random variations in the production and / or processing and / or arise in the object. Due to the random character, the features can not be predicted and not generated controlled. Random characteristics have high counterfeit protection. A reproduction and / or forgery of an object with randomly recognizable features is associated with a high outlay.

Examples of such random features are the unique fiber structure of paper (see WO05 / 088533A1), the (microscopic) course of printed images (see WO09 / 097974A) or the distribution of microreflectors in a transparent layer (see WO09 / 097979A).

The scanning of the surface by means of surface sensor is preferably carried out optically. In this case, the identifying feature is information derived by optical methods from the characteristic surface structure of the object. The identification feature is preferably storable and machinable. By storable is meant that the identifier can be taken up again at a later date, for example for comparison purposes. By machine processing is meant that the identifier can be machine read and subjected to various computational and / or memory operations with a machine. Suitable surface sensors for optical scanning are described, for example, in WO05 / 088533A1, DE102009017668.3, PCT / EP2009 / 002809, DE102009025061.1.

The optical scanning process includes at least the following steps:

(a) directing an electromagnetic beam to a surface of the object, (b) moving the electromagnetic beam and the object relative to each other such that the electromagnetic beam travels a path on the surface,

(c) recording a portion of the radiation reflected during the relative movement of the surface of the object as a function of time to obtain at least one scanning signal. The electromagnetic radiation may be coherent or non-coherent. If unwanted interference phenomena such as speckle patterns occur in optical scanning, a non-coherent radiation source is preferably used. The scanning is usually carried out with monochromatic radiation in the wavelength range of 300 nm to 1000 nm, preferably in the range of visible light or in the range of the near infrared. Part of the radiation impinging on the surface of the object is reflected back. The reflected radiation contains information about the nature of the surface. Usually, the object has a unique surface structure that scatters radiation in a characteristic manner. Part of the reflected radiation is detected by means of suitable detectors. In a preferred embodiment, the scanning of the object surface is performed with electromagnetic radiation along a line.

The scanning is preferably carried out with a point or line beam profile. A point beam profile produces a sample signal with a better signal-to-noise ratio than a line beam profile. In the case of a linear beam profile whose longer axis lies transversely to the direction of motion, as it were an averaging is carried out via a large number of the signals from punctiform beam profiles guided side by side.

As the size of the scan area decreases, it becomes increasingly difficult to retrieve the corresponding area detected during the first scan in a later scan for the purpose of identification and / or authentication. Therefore, a scan with a line-shaped profile is preferred over a point-shaped profile, even if it provides a worse signal-to-noise ratio than a scan with a point-shaped profile.

Surprisingly, it has been found that even then a scanning signal and a characteristic fingerprint for the purpose of identifying and / or authenticating an object can be determined when the beam profile is widened transversely to the direction of movement. This is shown schematically in FIG. By extending the beam profile in the direction transverse to the direction of movement, the problem of positioning is solved: Instead of a thin line (with a width corresponding to the extension of the point-shaped beam profile) becomes a wide area (with a width that the longer extension of the linear Beam profile corresponds) scanned. This wide range can be found correspondingly easier in a later scan.

A linear beam profile is defined here as follows: Usually, the intensity in the cross-sectional center of the radiation is highest and decreases toward the outside. The intensity can decrease evenly in all directions - in this case there is a round cross-sectional profile. In all other cases there is at least one direction in which the intensity gradient is greatest and at least one direction in which the intensity gradient is smallest. In the following, the beam width is understood to mean the distance from the center of the cross-sectional profile in the direction of the smallest intensity gradient, at which the intensity has dropped to half of its value in the center. Furthermore, the beam thickness is understood to be the distance from the center of the cross-sectional profile in the direction of the highest intensity gradient, at which the intensity has dropped to half of its value in the center. A linear beam profile refers to a beam profile in which the beam width is greater than the beam thickness by a factor of more than 10. Preferably, the beam width is larger than the beam thickness by a factor of more than 50, more preferably by a factor of more than 100 and most preferably by a factor of more than 150. Preferably, the beam thickness is in the range of the mean groove width of a profile element of the present invention Surface of the object (for the definition of the mean groove width see DIN EN ISO 4287: 1998).

It is known to the person skilled in the art how a corresponding beam profile can be generated for example by means of optical elements. Optical elements are used for beam shaping and focusing. In particular, lenses, diaphragms, diffractive optical elements and the like are referred to as optical elements.

During a scan, the handset is moved over the object surface. Usually, the handset is placed on the object, so that touch object and handset.

When using a linear beam profile for scanning a surface area, the beam width is transverse to the direction of movement. The angle between the direction of movement and the direction of the beam width is preferably between 10 ° and 90 °, more preferably between 45 ° and 90 °, most preferably between 70 ° and 90 °. The manual movement can be carried out continuously at constant speed, accelerating or decelerating, or discontinuously, ie, for example stepwise.

The radiation intensity incident on the detectors is detected as a function of time. Usually, measuring signals are recorded and updated at a constant measuring frequency. The irradiation (scanning) of the surface can take place at an arbitrary angle of almost 0 ° (if reflection still occurs) up to 90 ° relative to the mean surface level. The detection of the reflected radiation can also be carried out at an arbitrary angle of almost 0 ° to 90 ° relative to the mean surface level. Depending on the surface condition, it may be useful to detect directly reflected radiation (specular reflection) or scattered radiation (diffuse scattering). This can be determined by simple routine experiments. Decisive is the achieved signal-to-noise ratio, the reproducibility and the required positioning accuracy.

It is important that the same area is recorded for the most part during each scan. The applications WO09 / 097975A1, WO09 / 097980 and DE10200923536.1 describe ways in which the area which has been scanned in the so-called registration can be found again in later scans for comparison purposes.

In a preferred embodiment of the method according to the invention, a marking on the object is used as trigger for the beginning of the scanning. For this purpose, the scanning beams are guided over the surface of the object and a part of the radiation reflected by the surface is detected by means of a detector. The mark on the surface of the object causes a change in the signal detected by the detector. This signal change initiates the acquisition of the scanning signals, i. from the occurrence of the signal change, the time-dependent scanning signals are recorded.

It is also conceivable to use a corresponding marking also for the end of the recording of the scanning signals by recording the scanning signals until a characteristic signal change stops the recording process.

The marking may, for example, be a sharp change in contrast which results, for example, from a transition of a black print to a white print. Due to the high absorption of the black printing, the intensity of the reflected radiation arriving at the detector is low. At the transition from black printing to white printing, the intensity of the reflected radiation increases abruptly, which can be used as a trigger to trigger the recording of the scanning signals.

Preferably, markers already present on the article are used. For this purpose, for example, optical codes (barcode, matrix code), logos, fonts but also edges are suitable.

However, it is also conceivable that the user of the handset manually starts and / or stops the recording of the scanning signal. The known computer mice usually have at least one pressure switch (mouse button), with the help of which the user can control the process. It is conceivable, for example, for the user to start the recording of the scanning signal by pressing the mouse button and to stop recording the scanning signal by releasing the mouse button.

Simultaneously with the scanning, the movement of the handheld device is detected by means of a navigation sensor and the following step (d) follows the scanning:

(D) conversion of the sampling signal using the navigation signal into a time-independent sampling signal (intensity-location signal). The preferably normalized, time-independent scanning signal can be used directly as an identification feature.

As a rule, the identification feature is generated from the time-independent sampling signal by various mathematical methods such as filtering and / or background subtraction. These mathematical methods eliminate as far as possible random or systematic fluctuations resulting from individual measurements. Furthermore, it is conceivable to extract characteristic features from the signal in order to reduce the data quantity of the identification feature.

The identifier can be linked to the object. Such a linkage is usually made on the first scan of an object. The first scan for generating a first identifier is also referred to herein as registration. By means of the method according to the invention, a characteristic fingerprint is generated, which can be used in the form of preferably storable and machine processable data as a unique identifier for the object.

The linkage can be physical or virtual. In the case of a physical linkage, the identification feature may be in the form of an optical code (barcode, Matrix code, OCR text or the like) may be printed on the object or incorporated into the object. Likewise, it is conceivable to associate the object with a sticker which contains the identification feature stored. The attachment of an electronic data carrier on the object, such as an RFID chip on which the identification feature is stored, is conceivable.

In the case of a virtual link, for example, a unique number assigned to the respective object (ID number, batch number or the like) is linked to the identification feature in a database. For example, the identifier may include this number in a header (metadata at the beginning of a file). The link ensures that there is a clear and unambiguous association between the identification feature and the object. On the basis of the identification feature can be clearly infer the associated object.

At a later time, an identifier can be generated again from the object. This second identifier can be used to identify and authenticate the item. Details can be found in the following applications: WO 09 / 097975A 1, WO 09 / 097974A 1, WO 09 / 097979A 1 and WO09 / 097980A1.

In principle, the object can be any object which has characteristic features which can preferably be detected optically. The hand-held device according to the invention is particularly suitable for objects with flat surfaces such as documents, labels, packaging boxes or the like.

In a preferred embodiment, the handset according to the invention has a leading edge. To scan an object, the leading edge of the handset is pressed against an edge of the object to be scanned. The movement of the handset over a surface of the object is along the leading edge. The leading edge restricts the freedom of movement of the handheld device.

Usually, the handset rests on a surface of an object. If the object surface to be scanned is not transverse to the direction of gravity, it is also conceivable to press the hand-held device against the object surface. Due to the object surface, the possibility of movement of the hand-held device is limited, because a scan is usually carried out with the hand-held device in contact with the object surface. The leading edge causes a further restriction of the possibility of movement, because the scanning takes place along the leading edge (in the positive or negative direction, ie "forward" or "back").

Due to the movement along the leading edge, the movement of the handheld device in space is thus predetermined. This makes it easier for the user to reproducibly detect a predetermined scanning area on the object surface.

In a preferred embodiment, the hand-held device according to the invention is designed specifically for scanning such objects which have at least one flat surface which has at least one straight terminal edge. The hand-held device according to the invention is placed on the flat surface of the object or pressed against the flat surface of the object. The leading edge of the handset is pressed against the trailing edge of the object surface. For scanning, the hand-held device is moved over the object surface, while the leading edge and the trailing edge remain in contact.

Examples of such objects are paper documents and packaging boxes such as medicine boxes or packets of cigarettes.

A hand-held device with a leading edge is also particularly suitable for scanning labels applied to an object. As explained in detail in WO2009 / 097980A, it may be advantageous to identify or authenticate an object based on a label associated with the object. In such a case, instead of characteristic features of the object, characteristic features of the label are used to identify or authenticate the object. The label is connected to the object so that it can not be removed indelibly. The edges of a label are very suitable for the guidance of a handheld device. The leading edge of the handheld is pressed against one edge of the label to scan.

Surprisingly, it was found that paper documents can also be scanned manually. As is known, because of their small thickness, paper documents are not stiff but pliable. Nevertheless, the hand-held device according to the invention can be moved with a corresponding leading edge along an edge of a paper document without the paper document bending in the process. In a preferred embodiment for scanning objects with a comparatively small thickness, such as paper documents or labels, the hand-held device according to the invention has a leading edge with a height h in the range from 0.05 mm to 1 mm, preferably from 0.2 mm to 0.8 mm. more preferably from 0.3 mm to 0.6 mm. Another important factor in scanning thin objects such as paper documents or labels is the radius of curvature of the edge adjacent to the object during scanning (see FIG. 2). This radius of curvature should be as small as possible to prevent slipping. The radius of curvature is preferably less than 50 μιη, more preferably less than 20 μιη, most preferably less than 5 μιη.

The hand-held device according to the invention can be designed as a computer mouse. For mobile applications, it is also conceivable to carry out the inventive handset as a mobile phone.

The invention is explained in more detail below by means of examples, without, however, limiting them to them.

Show it:

Figure 1 (a), (b), (c): Schematic representation of a hand-held device according to the invention with a

Leading edge (a) from above, (b) from below and (c) in cross section along a straight line through points A and B Figure 1 (d): Cross section through the surface sensor of the handset according to the invention

Figure 1 (a) along a straight line through the photodetectors

Figure 2: Enlarged view of the handset of Figure 1 (a) in the region of the leading edge

Figure 3: Schematic representation for explaining a line-shaped beam profile

Figure 4: Schematic representation of a hand-held device according to the invention with two

leading edge

Figure 5: Schematic representation of a hand-held device according to the invention with a circular

leading edge

Figure 1 shows schematically a preferred embodiment of the hand-held device according to the invention. In Fig. 1 (a), this is shown from below, in Fig. 1 (b) from above and in Fig. 1 (c) in cross section along a straight line through the points A and B of Fig. 1 (a). The hand-held device 10 according to the invention has a navigation sensor 11 and a surface sensor 12, which face the object surface to be scanned during operation of the hand-held device. The navigation sensor is shown in the figure in the form of a hatched area as a functional unit, without further details are given. About the variety of possible navigation sensors reference is made to literature on computer mice. As illustrated above, the navigation sensor preferably operates optically.

In the present case, the surface sensor has a source of electromagnetic radiation (2) and two photosensors (5, 5 '). As shown in Figure 1 (d), when scanning the surface of an object 1, a scanning beam 3 is sent perpendicular to the surface. Part of the surface scattered radiation 4 is collected by the detectors.

The movement of the handset 10 occurs while the guide rail 16 is pressed against an edge of the object. In Fig. 1 (c), the movement is perpendicular to the plane of the drawing, in Fig. 1 (d), the movement is in the direction of the thick arrow.

The beam profile for scanning the surface is preferably linear as shown in Fig. 3. The longer axis of the linear beam profile is preferably transverse to the direction of movement, in the present case preferably perpendicular to the direction of movement.

It is also conceivable to use only a single detector or more than two detectors instead of the two photodetectors.

In Figure 2, the region of the leading edge of Fig. 1 (a) is shown enlarged. The height h of the leading edge is preferably adapted to the object. The leading edge has a curvature K, the radius of which, as explained above, should be as small as possible in order to avoid slippage of the handheld device when scanning along an object edge.

As shown in Figure 4, the handset may also have multiple leading edges. In the embodiment shown in FIG. 4, the handset has two guide edges running parallel to each other at a distance from each other. Such an embodiment is particularly suitable for scanning labels: the label fits exactly between the leading edges and the leading edges prevent the handset from slipping off the label edges during scanning.

The leading edge can in principle have any course; in the example of Figure 5, it has a circular shape. The hand-held device shown in FIG. 5 is suitable for scanning round objects. The handset is subject to the circular recess on the rounds mounted and scanned during a manual rotational movement about an axis through the center of the circular recess.

Figure 4 shows schematically a preferred method for scanning a surface. An area 7 of a surface 1 of an object is irradiated by means of a source of electromagnetic radiation 2. Part of the reflected radiation 4 is picked up by a detector to pick up a scanning signal. The object is moved relative to the radiation source and detector assembly (represented by the thick black arrow). In the surface plane is a line-shaped beam profile, the longer extension is transverse to the direction of movement.

Reference numerals:

1 object

2 source of electromagnetic radiation

3 scanning beam

4 reflected rays

5 detector

5 'detector

6 linear beam profile

7 scanned area

10 inventive handset

11 Navigation sensor

12 surface sensor

13 switches

14 switches

15 connection e.g. to a computer

16 leading edge

16 'leading edge

Claims

claims

1. Hand device for detecting characteristic features of an object surface, which can be manually guided over the object surface, at least comprising

a surface sensor for detecting characteristic features of an object surface, a navigation sensor for detecting movements of the hand-held device on the object surface.

The handset of claim 1, wherein the surface sensor comprises at least one source of electromagnetic radiation capable of emitting radiation to the surface of an object, and wherein the surface sensor comprises at least one detector with the at least a portion of the radiation returned from the surface of the object as a function the time can be recorded.

3. Hand tool according to claim 2, characterized in that the source of electromagnetic radiation is designed so that it can form a line-shaped beam profile on an object surface.

4. Hand tool according to one of claims 1 to 3, further comprising a leading edge, so that the guide of the handset can be made via an object surface by means of the leading edge along an object edge.

5. Hand tool according to claim 4, characterized in that the leading edge has a height of 0.05 mm to 1 mm, preferably from 0.2 mm to 0.8 mm, particularly preferably from 0.3 mm to 0.6 mm.

6. Hand tool according to claim 5, characterized in that the leading edge has a radius of curvature smaller than 50 μιη, preferably less than 20 μιη, more preferably less than 5 μιη.

The handset of any one of claims 1 to 6, wherein the navigation sensor comprises at least: a light source for illuminating a portion of the object surface, thereby producing reflected images, a detector for generating digital images based on the reflected images, and means for performing a motion calculation on the digital images to obtain motion data indicative of relative motion between the navigation sensor and the object surface.

8. A method for detecting characteristic features of an object surface, characterized in that a hand-held device is manually guided over the object surface and scanned by means of a surface sensor, the surface and an intensity-time signal is generated, wherein detects the movement of the handset by means of a navigation sensor and a Navigation signal is generated, and the intensity-time signal is converted by the navigation signal into an intensity-location signal.

9. The method according to claim 8, characterized in that the scanning is carried out with electromagnetic radiation, wherein at least a part of the radiation returned by the object surface is detected as a function of time.

10. The method of claim 9, wherein the scanning is carried out with a linear beam profile.

Method according to one of claims 8 to 10, characterized in that the hand-held device is pressed by means of a leading edge against a stop edge of the object and guided along the stop edge over the object surface.

Method according to one of claims 8 to 11, comprising the steps

(a) directing an electromagnetic beam to a surface of the object,

(b) moving the electromagnetic beam and the object relative to each other such that the electromagnetic beam travels a path on the surface,

(c) recording a portion of the radiation reflected during the relative movement of the surface of the object as a function of time to obtain at least one scanning signal;

(d) converting the sampling signal using the navigation signal into a time-independent sampling signal,

(e) optionally: associating the time independent sampling signal with the object.

13. Use of a hand-held device according to one of claims 1 to 7 for receiving identification features for the purpose of identification and / or authentication of

Objects.

14. Use according to claim 13, characterized in that the identification features of paper documents are recorded.

15. Use according to claim 13, characterized in that the identification features of labels which are connected to objects are recorded.