DE102016100361A1 - Method and device for scanning an object with an imaging method - Google Patents

Abstract

The invention relates to a method for scanning an object with an imaging method, the method comprising the steps: Simultaneous illumination of an object with at least two different light sources, wherein the light sources have different light spectra, scanning the object by means of at least two sensors, the one have different spectral sensitivity, and - separating the intensities of the light spectra of the at least two light sources in the sensor signals detected by the sensors by means of specific sensitivities of the respective sensors for the different light spectra.

Description

The present invention relates to a method and a device for scanning an object with an imaging method, wherein in particular at least two different light sources are used for illuminating the object to be scanned.

In the inspection of products using imaging techniques, the illumination, and in particular the angle of incidence with which the light shines on an object to be scanned, is of central importance for the detection of defects.

• 1. Dunkelfeldbeleuchtung
• 2. Hellfeldbeleuchtung
• 3. Durchlichtbeleuchtung

There are basically three types of lighting:

• 1. Dark field illumination
• 2. bright field illumination
• 3. Transmitted light illumination

In the dark field illumination, the light is deflected by means of Lichtstrahllenkmitteln (reflector, lens) of the light source such that a direct (specular) reflection of the light is avoided .. In bright field illumination, the light emitted from the light source in a
Angle on the object so that it is reflected towards a camera.

The transmitted light illumination is used for transparent objects to be scanned, the light source being arranged on one side of the object and the sensors for detecting the light passing through the transparent object on the other side of the object.

In the case of materials which have both diffuse and glossy reflection properties and are also transparent, the three types of illumination can simultaneously recognize different types of possible defects. So z. For example, with a bright field illumination error in a paint structure, with a dark field illumination error in the paint application and with the transmitted light illumination inclusions in a transparent area can be detected.

These types of lighting and modifications thereof are known to be able to detect different defects in products as automatically as possible.

Often it is useful to provide two different types of lighting simultaneously. Since, with simultaneous illumination, the light of one illumination type is superimposed with the light of the other illumination type, it is not readily possible to use two different illumination types at the same time. Therefore, the individual lighting types are often used in a time division multiplex, i. h., That the individual lighting types are switched on one after the other in succession. As a result, the individual lighting types do not interfere with each other. However, the possible throughput in scanning the objects is reduced since the object can not be scanned simultaneously with all types of illumination.

It is also known to design the individual lighting types with spectrally different light sources and to provide a plurality of cameras which are provided with special filters, so that each camera can only receive the light of a certain type of lighting. Such a device has the advantage that an object to be monitored with several types of lighting can be scanned simultaneously. The disadvantage of this is that several cameras must be provided and the quality of the filters must be high in order to separate the light of the different light source precision.

In principle, it would also be conceivable to use a color camera, which as a rule has different sensors which are each sensitive to a specific color or a specific spectral range. If one were to use light sources which would each be detected by one sensor type of the color camera, then one could spectrally separate the individual types of illumination with a color camera without additional filters. However, this is not possible with conventional, commercially available color cameras, since the individual spectral sensitivity ranges overlap different sensor types, so that the individual sensor types each detect light from light sources with different light spectra. As a result, it is not possible to assign the sensor signals clearly to a specific light source. This effect is referred to below as spectral overcoupling.

The invention has for its object to provide a method and apparatus for scanning an object with an imaging method in which the object simultaneously with different Lighting cycles can be irradiated and with simple and inexpensive means the light of the respective types of lighting can be reliably detected.

The object is achieved by the objects specified in the independent claims. Advantageous embodiments are specified in the respective subclaims.

• – Gleichzeitiges Beleuchten eines Objekts mit zumindest zwei unterschiedlichen Lichtquellen, wobei die Lichtquellen unterschiedliche Lichtspektren aufweisen,
• – Abtasten des Objekts mittels zumindest zweier Sensoren, die eine unterschiedliche spektrale Empfindlichkeit aufweisen, und
• – Separieren der Lichtspektren der zumindest zwei Lichtquellen in den mit Sensoren erfassten Sensorsignalen mittels spezifischer Empfindlichkeiten der jeweiligen Sensoren für die unterschiedlichen Lichtspektren.

An inventive method for scanning an object with an imaging method comprises the following steps:

• Simultaneous illumination of an object with at least two different light sources, wherein the light sources have different light spectra,
• - Scanning of the object by means of at least two sensors having a different spectral sensitivity, and
• Separating the light spectra of the at least two light sources in the sensor signals detected by sensors by means of specific sensitivities of the respective sensors for the different light spectra.

The inventor of the present invention has recognized that the above-explained spectral coupling leads to the sensors to output signals that are not directly usable, but based on the specific sensitivities of the respective sensors for the different light spectra of the light sources, the light intensities by these light spectra in caused by the sensor signals are separable. Each sensor type has a certain specific sensitivity for the respective light spectrum emitted by a light source. With two light sources and two sensors, this results in four specific sensitivities that can be displayed in a 2 × 2 matrix. These specific sensitivities can be easily measured in advance by directing light from the individual light sources to the sensors independently and detecting the intensity of the sensor signals. If the inverse matrix of the specific sensitivities, which are referred to below as the separation matrix, is multiplied by the vector of the sensor signals, a vector is obtained which describes the intensities of the light of the respective light sources at the sensors. Thus one obtains for each light source an intensity value of the light which has arrived from the light source to the sensors. The intensities caused by the individual light sources at the sensors are thus separated.

As a result, it is not necessary to provide multiple cameras and high-quality spectral filters. The detection of the light can be detected with a conventional camera having a plurality of different sensors having a different spectral sensitivity. Such cameras are commercial mass-produced, which are available at low cost. The sensor signals need only be separated into the individual light spectra by means of a separation matrix.

Such matrix multiplication is often integrated into cameras to correct for color rendering. Instead of a conventional correction matrix for correcting the color reproduction, the separation matrix can be used in the invention to separate the individual light spectra of the different light sources. Thus, in a simple embodiment, existing hardware can be used, but with the use of the separation matrix a completely different effect is achieved.

The different light sources preferably have light beam steering means with different geometry. Light beam steering means include reflectors and lenses. A bright field illumination preferably has a reflector and / or a lens, which direct the light in a rectilinear bundle of light rays onto the object to be scanned. In a dark field illumination, one or more reflectors are provided which direct the light from as different directions as possible to the object to be scanned. Accordingly, the geometries differ between the reflectors and lenses of a bright field illumination and a dark field illumination.

Preferably, the object is scanned with a color camera, which has sensors with at least three spectrally different light sensitivities. The sensors are usually sensitive to the colors red, green or blue. Such color cameras are available as line scan cameras or surface cameras in various designs on the market. They are produced in large quantities, which is why they are available at low cost. These cameras have a variety of sensors with the same spectral sensitivity. If such a camera extends in one or two dimensions, then the individual sensors can be irradiated with different light intensities due to the geometry of the light beam steering means. In most cases, illumination inhomogeneities result in which the light intensity in the edge region is lower than in the center. The sensor signals can be corrected locally with appropriate correction factors. Such a correction is called shading correction.

Furthermore, the individual sensors of a camera can have considerable deviations in the respective sensitivity. The differences can be up to 10%. This effect is often referred to as PRNU (photo response nonuniformity). This effect can also be corrected with appropriate correction values. These are to be determined separately for each sensor element. Since this PRNU correction value can be different for each sensor, it is sensor-dependent and thus again location-dependent.

Since the deviations due to the PRNU effect are caused by the sensors themselves, the measured sensor values (s _r , s _g , s _b ) can first be corrected with the PRNU correction coefficients, then separated with the separation matrix (M _SEP ) and afterwards corrected with the correction factors for the illumination inhomogeneities, to obtain the intensities of the light received from the individual light sources at the sensors. The illumination inhomogeneities cause a different distribution of the light intensity at the individual sensors. Since the spectral crosstalk depends on the light intensity, this correction can only be performed on the already separated intensity values. Mathematically speaking, this means that the correction of the illumination inhomogeneities, the separation by means of the separation matrix and the PRNU correction are not commutative. The order of these operations can not be swapped.

Conventional cameras often correct the influence of illumination (shading effect) and sensitivity differences (PRNU effect) with a set of common correction coefficients. This is not possible without consideration of the separation matrix.

However, it is possible to specify a location-dependent separation matrix for each sensor of a camera, which is already corrected in accordance with the PRNU effect and / or illumination inhomogeneities.

The invention will be explained in more detail by way of example with reference to the accompanying drawings. The drawing shows in:

1 schematically a device for scanning objects which are moved along a conveying direction in a side view,

2 the device off 1 in a front view,

3 the device off 1 and 2 in a sectional view along the line AA in 2 .

4 a diagram showing light spectra of different light sources and spectral sensitivities of different sensors, and

5 schematically a device for scanning objects with multiple lighting devices in a side view.

An embodiment of a device according to the invention 1 for scanning objects is adjacent to a conveyor belt 2 arranged on the objects to be scanned 3 rest and in a conveying direction 4 to get promoted ( 1 . 2 ). The conveyor belt 2 is from two endless transport belts 5 formed, which at the ends of the conveyor belt 2 each about roles 6 are guided so that the transport belt 5 each an upper strand 7 and a bottom strand 8th form. The transport belts 5 are arranged parallel to each other and a distance from each other. On the upper run 7 the transport belt 5 are the objects to be scanned 3 on.

In the present embodiment, the scanning device comprises 1 an upper scanning unit 9 and a lower scanning unit 10 ,

One to the upper scanning unit 9 very similar lighting device is in the DE 10 2015 101 252.9 why reference is made to this patent application.

This upper scanning unit 9 has two reflector arrangements 11 . 12 on ( 3 ). Each of the reflector arrangements 11 . 12 is from a channel-shaped reflector 13 and a planar reflector 14 educated. The trough-shaped reflector 13 has a cross-section ellipsenabschnittsförmige mirrored reflector surface 15 on.

At an edge region of the channel-shaped reflector 13 is one on the side of the reflector surface 15 protruding light source holder 16 arranged. At the light source holder 16 are light-emitting diodes as light sources 17 intended. The light-emitting diodes 17 are so on the light source mount 16 arranged them with their radiation direction on the reflector surface 15 are directed. On to the light source holder 16 opposite edge of the channel-shaped reflector 13 closes the planar reflector 14 at. The planar reflector 14 has a mirrored reflector surface 18 on, on the same side as the reflector surface 15 the channel-shaped reflector 13 is arranged.

The two reflector arrangements 11 . 12 are with their reflector surfaces 15 . 18 arranged opposite each other. Furthermore, the two reflector arrangements 11 . 12 symmetrical to a plane of symmetry 19 the scanning device 1 arranged.

The upper scanning unit 9 has a housing 20 with two longitudinal side walls 21 , two diametrically opposite end walls 22 and a bottom wall 23 on. The planar reflectors 14 are perpendicular to the bottom wall 23 arranged. The bottom wall 23 is in the range between the two reflector arrangements 11 . 12 except and forms a passage opening 24 from which light can escape.

Adjacent to the plane of symmetry 19 is a retaining rail 25 arranged, extending between the opposite end walls 22 extends. On the retaining rail 25 are light emitting diodes 26 arranged in rows. The light-emitting diodes 26 are with their radiation direction towards the passage opening 24 directed and form a bright field illumination.

That of the light-emitting diodes 17 emitted light is first at the respective adjacent channel-shaped reflector 13 reflected. From the channel-shaped reflector 13 Much of the light is on the planar reflector 14 the opposite reflector arrangement 11 . 12 directed. A small part of the light-emitting diodes 17 emitted light is also directly from the channel-shaped reflector 13 to the passage opening 24 steered and emerges outwards.

The plane reflector 14 Reflected light is mostly through the passage opening 24 directed. A small part is returned to the opposite planar reflector 14 steered and reflected there again before passing through the passage opening 24 exit. These single, double and triple reflected light beams form a diffused light with homogeneous illuminance. A predetermined, strip-shaped area adjacent to the passage opening 24 is illuminated evenly. This strip-shaped area is hereinafter referred to as lighting area 27 designated.

The light-emitting diodes 17 form together with the reflector arrangements 11 . 12 a dark field illumination.

This dark field illumination is on the one hand very compact and on the other hand produces a very homogeneous illumination in the lighting area 27 , In the context of the invention, of course, other reflector arrangements can be provided which also produce a diffuse illumination to form a dark field illumination.

The scanning device 1 is with its symmetry plane 19 transverse to the conveying direction 4 arranged.

On the two upper dreams 7 the transport belt 5 are the objects to be scanned 3 on. The upper dreams 7 thus define a transport level 28 ,

Below the transport level 28 is a line-shaped light source arrangement 29 in the lowest scanning unit 10 arranged, which extends over the entire length of the lighting area 27 , ie in the area between the opposite end walls 22 the upper scanning unit 9 extends. The light source arrangement 29 has light emitting diodes 30 on, the line-shaped and with their emission direction towards the passage opening 24 are aligned. The light-emitting diodes 30 the lower scanning unit 10 thus stole light up through the through hole 24 from.

In the upper scanning unit 9 is a holder 31 to take a camera 32 intended. The camera 32 is preferably a line scan camera, which in particular over the entire length of the scanning device 1 that is, between the opposite end walls 22 , extends to the entire lighting area 27 to be able to feel. The camera 32 however, it can also be an area camera.

The camera 32 can be equipped with a zoom lens. The camera 32 is basically with a view to the passage opening 24 aligned.

A below the passage opening 24 located object 3 is with the light emitting diodes 17 with dark field light, with the LEDs 26 with bright field light and with the LEDs 30 irradiated with transmitted light.

The light sources of the dark field illumination (light emitting diodes 17 ), the field illumination (LEDs 26 ) and the transmitted light illumination (LEDs 30 ) are each designed to emit light having a different light spectrum. In the present embodiment, the light-emitting diodes 17 for the dark field illumination blue, the light emitting diodes 26 for the bright field illumination green and the light emitting diodes 30 for the transmitted light illumination red emitting light emitting diodes. In 4 are the blue light spectrum 33 , the green light spectrum 34 and the red light spectrum 35 drawn the different LEDs.

The camera 32 is a color camera that has sensors with different spectral sensitivity. In the present embodiment, the camera 32 an RGB camera with sensors with blue, green and red spectral sensitivity. In 4 are the blue spectral sensitivity 36 , the green spectral sensitivity 37 and the red spectral sensitivity 38 located. How to look out of the diagram 4 the spectral sensitivities overlap 36 . 37 and 38 considerably. In particular, the green spectral sensitivity 37 overlaps strongly with the blue spectral sensitivity 36 and the red spectral sensitivity 38 and extends into the areas of the blue light spectrum 33 and the red light spectrum 35 , But also the blue spectral sensitivity 36 and the red spectral sensitivity 38 extend into the areas of the differently colored light spectra. As a result, the above-described spectral overcoupling is caused.

wobei ein Vektor s mit den Koeffizienten s_r, s_g, s_b die Sensorsignale für rot, grün und blau für einen Bildpunkt, der Vektor a mit den Koeffizienten a_r, a_g, a_b die Antwort des abzutastenden Objekts 3 auf die Beleuchtung mit den drei Lichtspektren Rot, Blau und Grün und die Matrix M_K mit den Koeffizienten k00 bis k22 die Kopplung der unterschiedlichen Lichtspektren darstellt. The spectral overcoupling can be expressed by the following formula:

wherein a vector s with the coefficients s _r , s _g , s _b, the sensor signals for red, green and blue for a pixel, the vector a with the coefficients a _r , a _g , a _b, the response of the object to be scanned 3 on the illumination with the three light spectra red, blue and green and the matrix M _K with the coefficients k00 to k22 represents the coupling of the different light spectra.

The responses a _r , a _g , a _b represent physically the light intensities of the light reflected or transmitted by the scanned object of the three spectrally different light sources at the respective pixel of the sensor.

The coefficients k00 to k22 of the coupling matrix M _K are physically the specific sensitivities of the red sensor (k00, k01, k02) for the red, blue and green light spectrum, the green sensor (k10, k11, k12) for the red, blue and green Light spectrum and the blue sensor (k20, k21, k22) for the red, blue and green light spectrum. The formula (1) can thus also be written as follows: s = M _K × α (2)

A separation matrix M _SEP is defined as an inverse matrix of the coupling matrix M _K : M _SEP = M - / 1K (3)

Hereby applies: α = M _SEP × s (4) wherein the signal intensities (s _r , s _g , s _b ) are converted or separated into the responses or light intensities (a _r , a _g , a _b ) at the respective pixel of the camera.

The coupling coefficients (k00-k22) can be determined using a calibration method. The calibration method calibrates the bright field illumination, the dark field illumination and the transmitted light illumination independently of each other.

To calibrate the bright field illumination is a flat, mirrored object 3 used the light emitting diodes 26 the brightfield lighting is switched on and the signals of the red, green and blue sensor are detected. These signal values form the corresponding coupling coefficients.

Calibrating the dark field illumination becomes an object 3 used with a flat, white surface. This object 3 is using light from the light emitting diodes 17 irradiated and with the camera the corresponding signals for the colors red, green and blue are generated. These signal values correspond to the corresponding coupling coefficients for the dark field illumination.

When calibrating for the transmitted light illumination, no object is in the illumination area 27 provided so that the light from the lower scanning unit 10 with the LEDs 30 unhindered to the camera 32 can get. The signals recorded by the camera for the colors red, green and blue form the coupling coefficients for the transmitted light illumination.

During calibration, a signal vector s is generated for each pixel in each case. During calibration, all the signals for the bright field illumination, the dark field illumination and the transmitted light illumination are preferably averaged on their own and the average values are used as coupling coefficients. The different efficiency of the lighting types is taken into account by the choice of the illuminance or the luminance, so that they generate approximately the same signals on the camera. Alternatively, it may be expedient to normalize the coupling coefficients for the bright field illumination, the dark field illumination and the transmitted light illumination respectively with specific normalization coefficients for the bright field illumination, the dark field illumination and the transmitted light illumination, with which the different, principle-dependent light intensities are taken into account in the three calibration processes.

If the coupling coefficients and thus the coupling matrix M _{K are} known, the separation matrix M _SEP can be determined by calculating the inverse matrix.

Often cameras already have a module for multiplying the signal vector s with a matrix to correct the color reproduction. In the invention, the separation matrix M _{SEP is} used in such a module as the matrix, whereby the sensor signals (s _r , s _g , s _b ) into the responses or light intensities (a _r , a _g , a _b ) of the individual spectrally different light sources be separated.

Optionally, a correction of the light intensities can be performed. In principle, a distinction is made between the correction of the illumination inhomogeneity and the correction of the different sensitivities of the sensors (PRNU).

The illumination inhomogeneities result from the geometry of the light sources and the light beam steering means, with which a light beam is generated, which is not exactly homogeneous as a rule. This will cause the different pixels of the camera 32 illuminated with different light intensities. To describe the light intensities due to the illumination inhomogeneities, an attenuation vector sb _x with the coefficients sbr _x , sbg _x and sbb _{x is} introduced. These attenuation coefficients differ for the different light spectra of the different light sources and are each dependent on location. The following description applies to a one-dimensional line scan camera in which a plurality of pixels are arranged side by side in the X direction. In the case of an area camera, the pixels are distributed in the X and Y directions, so that the attenuation coefficients depend on both the X and Y directions.

A response vector a _bx corrected for the illumination inhomogeneities by means of the location-dependent attenuation factors sbr _x , sbg _x , sbb _x results as follows:

In the method of sampling the objects from the signal vector s, since the response vector a is calculated, the components of the response vector a calculated by the formula (4) must be multiplied by the inverse of the attenuation factors to obtain the correspondingly corrected responses from the signals.

This is described by the following formula:

The individual sensors of a camera can have different sensitivities. These sensitivities can be up to 10% different. This is called PRNU (photo response nonuniformity). The sensor signals are correspondingly corrupted, which can be expressed by corresponding attenuation factors ser _x , seg _x and seb _x . The actually measured sensor signals s _ex can be calculated from the actual desired sensor signals s as follows, taking into account the location-dependent attenuation coefficients specific to the respective light spectra:

The calculation of the responses a from the actually measured signals s _ex takes place taking into account both corrections according to the following formula:

Since the correction of the illumination inhomogeneities has an effect on the light directed to the sensors and the correction of the different sensitivities (PRNU) affects the detected sensor signals, in the calculation of the responses the sensor signals with the reciprocal values of the attenuation values for the different sensitivities must first be corrected, then separate with the separation matrix into the corresponding responses and then correct by means of the inverse of the attenuation values for the illumination inhomogeneities. These operations are not commutative, that is, they must not be reversed. Within the scope of the invention it may also be expedient to carry out no or only one correction, either the correction of the illumination inhomogeneities or the correction of the different sensitivities. Both corrections are location dependent. The separation matrix M _SEP is basically not location-dependent.

The determination of the answers (a _r , a _g , a _b ) can be realized as hardware by means of several multiplication stages, wherein the attenuation factors are location-dependent, ie stored separately for each sensor in a look-up table and for correcting the sensor signals of the respective sensor be read out. The determination of the response vector can also be realized by means of a software module which performs the corresponding matrix and vector multiplications.

The separation matrix M _SEP has the matrix coefficients m00, m01,... M22. By representing the matrix by its coefficients, the formula (8) given above can be represented and multiplied as follows:

Using this formula minimizes the number of arithmetic operations to be performed. For each sensor, an already corrected separation matrix is stored in a look-up table. Due to the location-dependent attenuation factors, these separation matrices are themselves location-dependent, which is why a separate separation matrix is stored in the look-up table for each sensor.

As can be seen from the formula (9), the attenuation values are in the denominator of the coefficients, which is why they act as amplification factors and amplify the actually measured signals accordingly.

With the methods explained above, light sources with different light spectra can thus be used and the sensor signals can be separated in such a way that a separate signal for the intensity caused by one of the light sources is determined at each sensor. This also sensors can be used, in which a spectral overcoupling occurs. There are no additional color filters necessary. With a device suitable for carrying out the method according to the invention, other scanning methods can also be carried out, in particular if further light sources emitting white light are used, in which case a color correction matrix is used instead of a separation matrix in order to produce approximately colourfast images.

The embodiment explained above uses a special lighting device for illuminating a strip-shaped lighting area in a planar manner. The invention may also be practiced with other lighting devices. 5 schematically shows in a side view of another embodiment, the four lighting devices 39 - 42 each having a common line-shaped area of an object plane 43 illuminate.

The lighting equipment 39 - 42 are line-shaped and each have line-shaped light sources such. As light-emitting diodes, and corresponding light-guiding means, which may be mirrored reflectors and / or lenses or lenses.

This scanning device 1 still has a camera 32 on, which is a line camera in the present embodiment, with which the object plane 43 is scanned linearly. The line scan camera 32 is with its optical plane 44 perpendicular to the object plane 43 aligned. Basically, it is also possible to use the line scan camera 32 to arrange such that the optical plane 44 an angle deviating from the right angle with the object plane 43 includes. In the field of optical level 44 between the object plane 43 and the line scan camera 32 is a semi-transparent mirror 45 arranged. A first of the lighting devices 39 is arranged such that the light emitted by it on the semi-transparent mirror 45 is directed and from the mirror to the line-shaped lighting area 46 in the object plane 43 is steered. The corresponding light beam from the semi-transparent mirror 45 to the line-shaped lighting area 46 runs approximately parallel to the object plane 43 ,

The lighting equipment 40 . 41 are arranged so that they with the emitted light beam, the line-shaped illumination area 46 illuminate, wherein the light beam at an angle of the object plane 43 be fed to the optical plane 44 the camera 32 does not form an angle of incidence and projection, so that of the lighting devices 40 . 41 emitted light at the object plane 43 not directly into the camera 32 is steered. The lighting equipment 40 . 41 thus generate a dark field light, the illumination device 40 the light at a shallower angle than the lighting device 41 to the object level 43 radiates.

The lighting device 42 is below the object plane 43 arranged and aligned such that the of the illumination device 42 radiated light the line-shaped illumination area 46 illuminates.

The lighting equipment 39 - 42 are designed such that at least two illumination devices emit light with different light spectra. Preferably, all generate lighting equipment 39 - 42 each light with a different light spectrum. By using the different light spectrums, the illumination area 46 simultaneously with the different lighting devices 39 - 42 be illuminated and the intensities of the light spectra of the different lighting devices 39 - 42 be separated, as explained in detail above with reference to the first embodiment.

Within the scope of the invention, two different illumination devices or light sources suffice 39 - 42 to simultaneously perform two different optical examinations on an object to be scanned. The object to be scanned is in the object plane 43 in the lighting area 46 arranged.

LIST OF REFERENCE NUMBERS

1

 contraption

2

 conveyor belt

3

 object

4

 conveying direction

5

 conveyor belts

6

 role

7

 Trum

8th

 Trum

9

 upper scanning unit

10

lower scanning unit

11

reflector assembly

12

reflector assembly

13

channel-shaped reflector

14

planar reflector

15

mirrored reflector surface

16

Light source support

17

led

18

mirrored reflector surface

19

plane of symmetry

20

casing

21

longitudinal side

22

end wall

23

bottom wall

24

Through opening

25

retaining rail

26

led

27

lighting area

28

transport plane

29

Light source arrangement

30

led

31

bracket

32

camera

33

blue light spectrum

34

green light spectrum

35

red light spectrum

36

blue spectral sensitivity

37

green spectral sensitivity

38

red spectral sensitivity

39

lighting device

40

lighting device

41

lighting device

42

lighting device

43

object level

44

optical level

45

semi-transparent mirror

46

lighting area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102015101252 [0031]

Claims (13)

Method for scanning an object ( 3 ) with an imaging method, the method comprising the steps of: - Simultaneously illuminating an object ( 3 ) with at least two different light sources ( 17 . 26 . 30 ), the light sources ( 17 . 26 . 30 ) different light spectra ( 33 . 34 . 35 ), - scanning the object ( 3 ) by means of at least two sensors which have a different spectral sensitivity ( 36 . 37 . 38 ), and - separating the intensities of the light spectra ( 33 . 34 . 35 ) of the at least two light sources ( 17 . 26 . 30 ) in the sensor signals detected by the sensors by means of specific sensitivities of the respective sensors for the different light spectra. A method according to claim 1, characterized in that the separating is done by multiplying the simultaneously detected sensor signals of the at least two sensors by means of a separation matrix, wherein the separation matrix is the inverse matrix of a matrix describing the specific sensitivities. Method according to claim 1 or 2, characterized in that the light sources ( 17 . 26 . 30 ) Light beam steering means ( 13 . 14 ) with different geometries. Method according to one of claims 1 to 3, characterized in that the object with a color camera ( 32 ) is sampled, which sensors with at least three spectrally different sensitivities ( 36 . 37 . 38 ), which are particularly sensitive to the colors red, green and blue. Method according to one of claims 1 to 4, characterized in that the spectral sensitivities ( 36 . 37 . 38 ) of the respective sensors partially overlap spectrally. Method according to one of claims 1 to 5, characterized in that the spectral sensitivities ( 36 . 37 . 38 ) of the respective sensors each one of the light spectra ( 33 . 34 . 35 ) of the light sources ( 17 . 26 . 30 ). Method according to one of claims 1 to 6, characterized in that in each case a plurality of sensors of the same spectral sensitivities are used, wherein the signals determined by the individual sensors are corrected location or sensor specific. Method according to one of claims 1 to 7, characterized in that the signals determined with the individual sensors with respect to the different sensitivities of the individual sensors (PRNU) are corrected. Method according to one of claims 1 to 8, characterized in that the separated intensities of the light spectra are corrected with respect to the illumination inhomogeneities. Device for scanning an object ( 3 ) with an imaging method comprising: - at least two different light sources ( 17 . 26 . 30 ) for simultaneously illuminating an object ( 3 ), each with different light spectra ( 33 . 34 . 35 ), - at least two sensors for scanning an object ( 3 ), which have a different spectral sensitivity ( 36 . 37 . 38 ), and - means for separating the light spectra ( 33 . 34 . 35 ) of the at least two light sources ( 17 . 26 . 30 ) in the sensor signals by means of specific sensitivities of the respective sensors for the different light spectra ( 33 . 34 . 35 ). Device according to claim 10, characterized in that the device ( 1 ) is designed to carry out a method according to one of claims 1 to 7. Apparatus according to claim 10 or 11, characterized in that the light sources light-emitting diodes ( 17 . 26 . 30 ). Device according to one of claims 8 to 10, characterized in that the at least two light sources are formed as at least two of the following three light sources: dark field light source, bright field light source, fluoroscopic light source

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