Non-contact fingerprint and palmprint recording apparatus and method

Abstract

The present invention relates to an apparatus and method for non-contact optical recording (comparable to contact printing) of papillary structures on the hand or parts thereof. The object of the present invention is to provide a device and method for non-contact optical recording of papillary structures of the hand, comprising: - a recess (30) in the upper area of ​​the device (4) for fingerprint recording, which serves the user for a rough orientation of the correct hand positioning (31); - an illumination part (1) for illuminating the hand or a part thereof (3) with structured light; a camera (2) for detecting light from said illumination unit (1) diffusely reflected from said hand or part thereof (3) in an object plane (21) of said camera (2), a camera (2) in which there is a non-zero difference between the distance from the object plane (17) to the camera and the distance to the lighting unit, in order to determine the position of the hand or part thereof (3) in relation to the depth of field range (9) of the camera (2) using a method for determining the size of structures in the images recorded by the camera (2); a calculation unit (29) for calculating the position by determining the structure size and for calculating said fingerprint image, This is achieved by an apparatus and method comprising:

Description

Technical Field

[0001] The present invention relates to an apparatus and method for non-contact optical recording (corresponding to contact printing) of papillary structures of the hand or parts thereof.

Background Art

[0002] An authority-compliant (contact type) multi-finger scanner is characterized by an image field that is at least 3.2 inches × 3.0 inches (width × height) at a scanning of 500 ppi. In non-contact recording of fingers, when considering that the curved surface of the finger is scanned up to an acceptable angle 7 defined at 500 ppi in order to capture the same area as a contact type scanner, as schematically shown in FIG. 2, significant oversampling (virtual measurement plane-based > 500 ppi) must occur. The resulting data volume can usually only be converted to three-dimensional coordinates in a non-negligible amount of time, which means that it is difficult to perform real-time control of the position of the hand in three-dimensional space when using conventional measurement techniques. For the actual measurement task of recording high-resolution fingerprints, camera 2 has a specific narrow depth of field range that can only focus on imaging the papillary structure of the finger. When the hand or finger is outside the depth of field of camera 2, faithful and detailed recording is impossible.

[0003] Known apparatuses for non-contact recording of fingerprints have different approaches regarding how to restrict or record the hand or finger.

[0004] U.S. Patent No. 10460145 (B2) discloses an apparatus for non-contact optical recording of hand features using two light sources and one camera. To take fingerprints, the hand must be moved through a vertically restricted space.

[0005] U.S. Patent No. 8600123 (B2) describes a non-contact fingerprint recording apparatus in which the recording amount is structurally limited to three dimensions and includes at least one camera for non-contact recording of fingers.

[0006] From the specification of Korean Patent Application Publication No. 20190097706 (A1), a non-contact fingerprint recording device that requires a distance sensor in addition to a recording camera is known.

[0007] In the specification of German Patent Application Publication No. 102019126419 (A1), the non-contact fingerprint recording device includes one multi-color illumination unit and at least two cameras for three-dimensionally recording the papillary structure of the hand.

[0008] A further device for optically imaging the papillary structure of the finger, which also has a similarly complex additional device for position detection, is known, for example, from the specification of US Patent No. 8971588 (B2).

[0009] Furthermore, the specification of US Patent No. 10885297 (B2) describes a non-contact recording device for biometric data, in which a camera and a light source are directed into an image recording area and a frame is attached to an electronic part that surrounds the recording area laterally. The shaft has a housing guide and an inlet gap for inserting the hand. The shaft defines the distance between the hand to be measured and a recording camera for imaging the hand or finger with respect to the frame. However, this disadvantage is that additional hardware such as an IR sensor is required to localize the hand or determine the position of the hand. This IR sensor should also be used to trigger the light source and the camera. Accurate knowledge of the position of the hand is important to realize a rapid application scenario where a complete three-dimensional image is generated and then processed when the hand is in the correct position.

Summary of the Invention

[0010] The present invention is based on the aim of finding new possibilities for non-contact fingerprint recording of a hand or part thereof, thereby making it possible to detect the distance of the hand in real time for three-dimensional image data recording of fingerprints without the need for an additional distance sensor or other additional hardware for determining the distance to a high-resolution camera.

[0011] This object is achieved according to the invention by claims 1 and 13.

[0012] Advantageous embodiments are described in the dependent claims.

[0013] The present invention is based on the idea that accurate knowledge of the current hand position is required to start three-dimensional recording or processing, or to provide a correction proposal for hand positioning to the user of the scanner.

[0014] The present invention is based on the basic idea of omitting an additional multi-part distance sensor for generating highly accurate three-dimensional image data of a hand or part thereof by using a combination of a specially arranged camera and projector and structured illumination of the hand in non-contact fingerprint recording for recognizing the distance of the hand (hand position). The three-dimensional image data of the preceding distance detection is determined from the camera image, and when an acceptable hand position exists, highly accurate three-dimensional image data is reconstructed pixel by pixel from the fingerprint image captured at high resolution and converted into a two-dimensional fingerprint image in a subsequent process.

[0015] The hand position detection should be performed with little computational effort and as a distance determination between the hand and the camera used as distance information either to offer the user a device correction proposal for correcting the hand position without an additional sensor, spatial limit measurement or complex scanning procedure, or to focus the camera accordingly, or to start a highly accurate reconstruction of three-dimensional image data when an accurate position for recording the hand exists.

[0016] The device includes an illumination unit that illuminates a spatial region, within which also lies the depth of field range of the camera, with structured light. The camera is configured to detect light diffusely reflected from a hand or a part thereof on the object plane. For this purpose, the illumination unit has a different distance from the depth of field range of the camera, because only then will the structural size of the structured illumination on the camera sensor be a function of the distance from the hand to the camera, and thus, by determining the structural size, it becomes possible to quickly spatially position a hand or a part thereof with respect to the fingerprint recording device.

[0017] The present invention realizes new possibilities for non-contact fingerprint recording of a hand or a part thereof and enables real-time hand distance detection for three-dimensional image data recording of fingerprints without the need for an additional distance sensor or auxiliary frame to determine the distance to a high-resolution camera.

Brief Description of the Drawings

[0018] The present invention will be described in more detail by the following exemplary embodiments and the drawings.

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[0019] According to the schematic representation of FIG. 1, the present invention includes, as a basic principle, an apparatus for fingerprint recording 4 and for measuring the distance 16 of the camera 2 to the object surface 21, and the camera 2 may also be provided for non-contact or contactless optical recording of the papillary structures of at least one finger. The apparatus 4 includes an illumination unit 1 for illuminating the measurement depth range 24 with structured light, and a camera 2 for detecting the light diffusely reflected from the hand 3 or a part thereof at the object surface 21, and there is a difference 17 between the distance 16 from the camera 2 to the object surface 21 and the distance 15 from the illumination unit 1 to the object surface 21.

[0020] According to the present invention, as shown in FIG. 1, the field of view 13 of the illumination unit 1 and the field of view of the camera 14 are described as the range where they overlap in the three-dimensional space. When the optical axis 11 of the illumination unit 1 and the optical axis 12 of the camera 2 are arranged in parallel, there is a lower limit of the measurement depth range 24. In the case of the shine-proof geometric arrangement of the camera 2 and the illumination unit 1 (see FIG. 8), the measurement depth range 24 also has a maximum distance. The measurement depth range 24 corresponds to the depth of field range 9 of the camera 2.

[0021] The illumination unit 1 included in the apparatus 4 is described by the optical axis 11, a spatial two-dimensional intensity modulator, the field of view 13 of the illumination unit, and a light source. If the illumination unit 1 additionally includes a lens for imaging the spatial two-dimensional intensity modulator, the illumination unit 1 is referred to as a projector 25 hereinafter. The illumination unit 1 in the sense of the present invention emits structured light and is particularly useful for wavelength emission (including spectral broadening). The illumination unit 1 can also be defined as being able to emit two or three wavelengths. A practical form of the illumination unit 1 may include, for example, one or more LEDs or one or more lasers (not shown).

[0022] Another embodiment of the illumination unit 1 emits a broad light spectrum such as a white light LED, a light source based on thermal radiation (incandescent bulb), or a gas discharge lamp.

[0023] In one embodiment of the present invention, the emission spectrum of the illumination unit 1 is within the range of 350 nm to 1000 nm. In a further embodiment of the present invention (see FIG. 3), in order to meet the MTF requirements of the FBI, the emission spectrum is limited to 450 nm to 550 nm.

[0024] In a preferred embodiment of the present invention, the operating distance 26 of the camera 2 is 50 mm or more and 1500 mm or less. This lower limit is the result of a sufficient distance to avoid contact between the hand 3 (or a part thereof) and the camera 2. This upper limit results from structural reasons.

[0025] In a more preferred embodiment of the present invention, the operating distance 26 of the camera 2 is 200 mm or more and 400 mm or less.

[0026] In a preferred embodiment of the present invention, the distance 28 from the illumination unit 1 to the average depth of field 27 of the camera 2 (or other possible cameras 2) is 50 mm or more and 1400 mm or less. In a more preferred embodiment, the distance 28 from the illumination unit 1 to the average depth of field 27 of the (at least one) camera 2 is 130 mm or more and 400 mm or less.

[0027] The camera 2 of the device 4 described by the optical axis 12 of the camera 2, the sensor, and the lens that forms an image on the sensor has a field of view 14 and a depth of field range 9 (limited by the lower limit 10 and the upper limit 8 of the depth of field range 9). Only within the depth of field range 9 can the papillary structure of the hand 3 (or a part thereof) be imaged on the sensor of the camera 2 with high quality in accordance with the specifications of the authorities (FBI Guidelines, Attachment F: Federal Bureau of Investigation, U.S. Department of Justice, "Electronic Biometric Transmission Specification (EBTS) with Technical and Operational Updates", version 10.0.9, May 22, 2018).

[0028] In a beneficial embodiment within the scope of the present invention, the camera 2 comprises an image sensor and a lens. The image sensor in the meaning of the present invention is a device that converts an optical signal into an electrical signal containing image information. According to the present invention, behind the image sensor (or the output of the camera 2), there may be an arithmetic unit 29 used for processing the image information. In particular, the arithmetic unit 29 is useful for calculating spatial information from the image of the image sensor, in particular for three-dimensional detection of the hand 3 or finger having a papillary structure.

[0029] In a beneficial embodiment (according to FIG. 8), the illumination unit 1 comprises a lens, thus forming a projector 25, the projector 25 used as the illumination unit 1 has structured illumination, and the camera 2 is mounted in a shine-proof geometric arrangement. This means that the projector 25 and the camera 2 achieve image equalization according to shine-proof based on the object plane 21.

[0030] In a more preferred embodiment (as outlined in FIG. 9), the beam paths of the illumination unit 1 and / or the camera 2 are folded via one or more deflection mirrors 5 to enable a compact design.

[0031] The two-dimensional intensity modulator within the scope of the present invention may comprise, for example, a digital light modulator composed of one or more DLP chips (Digital Light Processing), one or more LCDs (Liquid Crystal Device) or one or more LCoSs (Liquid Crystal on Silicon). Furthermore, according to the present invention, analog light modulators such as masks, slides, or scattering and phase modulation disks (for generating a speckle pattern) can also be used. Furthermore, the two-dimensional intensity modulator can include a diffraction element and / or a lens on the front surface, and a transmissive light image that can be rigid, rotated, or translated.

[0032] In a more preferred embodiment of the present invention, the illumination unit 1 or the projector 25 and the two cameras 2 are used, and the illumination unit 1 or the projector 25 is at a different distance from the depth of field range 9 as compared with the operating distance 26 of the camera(s) 2 (see FIG. 10), or two projectors 25 or two illumination units 1 and three cameras 2 are used, and the projector 25 or the illumination unit 1 is at a different distance from the depth of field range 9 as compared with the operating distance 26 of the camera 2 (see FIG. 11).

[0033] In a preferred embodiment of the present invention, the apparatus 4 has a feedback module 35, and the feedback module 35 provides information about accurate recording, correction proposals about the hand position, or other information to the user via acoustic, tactile, or visual signals or a combination thereof.

[0034] In a more preferred embodiment of the present invention, the feedback module 35 is configured as a display unit 36 in the form of a display, or can also be integrated as an LED line in the upper region of the apparatus 4.

[0035] The method according to the present invention for detecting in real time the distance from the hand 3 (or a part thereof) to the camera 2 is based on different distances from the camera(s) 2 and the illumination unit(s) 1 on the object plane 21 to the hand 3 (see FIG. 4).

[0036] The basic idea here is to measure the structural size 18 of the structured illumination on the sensor of the camera 2. According to the nomenclature in FIG. 4, the illumination unit 1 projects a spatially varying structure with a structural size 20 on the object plane 21 (S0). The structural size 19 on the light modulator of the illumination unit 1 is S p is. The distance 15 from the illumination unit 1 to the object plane 21 (A p ) represents the distance from the projector 25 used as the illumination unit 1 to the hand 3 (or a part thereof), and A c represents the distance 16 from the camera 2 to the object plane 21 of the hand 3.

[0037] Camera 2 (S C ) The measured structure size 18 of the structured illumination on the sensor of the camera 2 is a non-constant function of the distance 16 from the camera 2 to the object plane 21 (A c ), and it can be mathematically shown that there is a difference 17 (δ≠0) between the distance from the camera 2 to the object plane 21 and the distance from the illumination unit 1 to the object plane 21.

[0038] When δ≠0, S C = f(A c )

[0039] Next, this means that when the structure size 18 of the structured illumination projected by the projector 25 by the illumination unit 1 can be measured on the sensor of the camera 2 (S C ), the distance 16 from the camera 2 to the object plane 21 (A c ) can be determined when δ≠0, which solves the basic problem of distance measurement.

[0040] When δ≠0, A c = f(S C )

[0041] For example, in the case of projecting a periodic or quasi-periodic pattern such as a one-dimensional or two-dimensional sine wave pattern or a point pattern, the imaged structure size S C can be easily and efficiently determined, for example, from a discrete Fourier transform (DFT) or its fast implementation (FFT) by searching for the maximum value in the frequency space. This is also possible using a wavelet transform.

[0042] Figure 5 shows an intermediate step of the method presented for the projection of a sine wave pattern onto the hand 3 or a part thereof (finger of the hand) by a projector 25 having different distances 15 from the object plane 21 compared to the camera 2 used for recording. For almost equal distances to the hand 3 (or a part thereof) for the camera 2 and the illumination unit 1, there is a certain stripe distance or a certain spatial frequency (circular) in the camera image. When the projector 25 has only half the distance to the hand 3, an obvious improvement in the stripe distance can be seen at the distance 16 from the camera 2 to the object plane 21.

[0043] Figure 6 shows an intermediate step of the method presented herein for the projected aperiodic pattern (speckle). For distances to the object plane 21 that are almost equal for the camera 2 and the illumination unit 1, a dispersion of a constant structure size or a dispersion of a constant spatial frequency (circular) results in the camera image. When the illumination unit 1 has only half of the distance 16 to the hand 3 (or a part thereof), a clear improvement in the dispersion of the structure size can be seen at the distance 16 from the camera 2 to the hand 3.

[0044] When the method described herein is applied to several partial images, a low-resolution depth map of the recorded and illuminated scene can be generated, and it becomes possible to determine the rotation of the hand 3.

[0045] To determine the exact hand positioning 31, the distance of the hand 3 (or a part thereof) and the rotation (twisting) with respect to the depth of field range 9 are determined. With respect to the exact hand positioning 31, referring to FIG. 16, the part of the hand 3 to be measured must be placed in a plane within the depth of field range 9.

[0046] Image analysis 34 generally describes a method for determining the position and orientation of the hand 3 with respect to the camera 2 from the structure size 18 of the structured illumination from the illumination unit 1, which is imaged on the sensor of the camera 2. Special embodiments of the method have already been shown by way of example (see FIGS. 5 and 6).

[0047] In a preferred embodiment of the present invention, data recording is requested by the arithmetic unit 29, which triggers a trigger signal on the data bus. As a result, in the apparatus 4, at least one illumination unit 1 projects a stripe pattern, and an image of the hand 3 or a part thereof having the projected stripe pattern is synchronously recorded by at least one camera 2. This is transferred via a further data bus to the data processing unit of the arithmetic unit 29, where distance determination is performed by searching for maxima in the frequency space of the entire image, and rotation determination is performed by analyzing the maxima in the frequency space of the grid elements of the image. A correction determination is made based on the analysis result, which is made available to the user as feedback on the display unit 36 via another data bus. Then, an acceptable positioning of the hand 3 within the measurement depth range 24 is made, and further recording is started, which is communicated to the user via the display unit 36 and can continue either with new data recording via the camera 2 or with data processing for forming a three-dimensional image or a fingerprint image.

[0048] Figure 1 shows an apparatus 4 for non-contact optical recording of the papillary structure of the hand 3 or a part thereof, the apparatus 4 having an illumination unit 1 for illuminating the hand 3 (or a part thereof) with structured light and at least one camera 2 for detecting light diffusely reflected from the hand 3 or a part of the hand 3 onto the object surface 21, there being a substantially non-zero difference 17 between the distances 15, 16 from the illumination unit 1 and the camera 2 to the object surface 21, and the camera 2 having a depth of field range 9, which is limited by an upper limit 8 and a lower limit 10 of the depth of field range 9. A rapid measurement of the hand position is possible within the measurement depth range 24, which is given by the overlay region from the field of view 14 of the camera 2 and the field of view 13 of the illumination unit 1 and includes a part of the depth of field range 9 of the camera 2.

[0049] Figure 2 shows the definition of the acceptance angle 7, which limits the area of the recorded skin on the contact surface 6 in conventional fingerprint recording and must be drawn in accordance with the requirements (of the authorities) during non-contact recording.

[0050] Figure 3 shows the image sharpness in terms of the modulation transfer function (MTF) for the emission wavelength of the illumination unit 1. When it exceeds 640 nm, the FBI requirements for sharpness are not achieved at any point. The image sharpness was calculated for an optical imaging system having an operating distance of 200 mm at an F value of 2.5.

[0051] Figure 4 shows the relationship between the structural size 19 on the light modulator of the illumination unit 1, imaged at the structural size 20 on the object plane 21, in addition to the quantities shown in Figure 1. When the difference 17 between the distances 15, 16 from the illumination unit 1 and the camera 2 to the object plane 21 is non-zero, the illumination size 18 of the structured illumination on the sensor of the camera 2 is a function of the distance 16 from the camera 2 to the object plane 21.

[0052] Figure 5 shows an example of a method of expressing the relationship between the distance 16 from the camera 2 to the object plane 21 and the measured illumination size 18 of the structured illumination on the sensor of the camera 2 in the periodic pattern of the structured light of the illumination unit 1, which is useful for the calculation of the actual distance 16 from the camera 2 to the object plane 21 (where the positioning of the hand 3 or a part thereof is performed).

[0053] Figure 6 shows a further example of a method of the non-periodic pattern of the illumination unit 1, showing the relationship between the distance 16 from the camera 2 to the object plane 21 and the measured illumination size 18 of the structured illumination on the sensor of the camera 2.

[0054] Figure 7 shows a preferred embodiment of an apparatus 4 for non-contact optical recording of the papillary structure of the hand 3 or a part thereof, the apparatus 4 having a projector 25 for illuminating the hand with structured light and a camera 2 for detecting the light diffusely reflected from the hand 3 or a part thereof, and the projector 25 as the illumination unit 1 having a non-zero difference 17 between the distances 15, 16 from the illumination unit 1 and the camera 2 to the object plane 21 so as to be able to use the method of determining the position of the hand 3 (or a part thereof) substantially as described in Figures 5 and 6.

[0055] FIG. 8 shows a preferred embodiment corresponding to FIG. 7. The difference from FIG. 7 is that the camera 2 and the lighting unit 1 are arranged in a shine-proof geometric arrangement. As a result, on the one hand, the areas not illuminated by the lighting unit 1 cannot appear in the camera image at all, and on the other hand, there is an advantage that the depth-of-field ranges 9 of the camera 2 and the lighting unit 1 can be arranged in a parallel and overlapping manner.

[0056] FIG. 9 shows a preferred embodiment based on FIG. 8. The difference from FIG. 8 is that in order to achieve a more compact and space-saving design of the device 4, the beam paths of the camera 2 and the lighting unit 1 are folded via a deflection mirror 5.

[0057] FIG. 10 shows a preferred embodiment of the device 4 for non-contact optical recording of the papillary structure of the hand 3 or a part thereof. The device 4 has one projector 25 for illuminating the hand with structured light and two cameras 2 for detecting the light diffusely reflected from the hand 3 or a part thereof. There is a substantially non-zero difference 17 between the distances 15, 16 from the lighting unit 1 and the camera(s) 2 to the object plane 21. This structure of the additional camera 2 can expand the spatial field of view in the sense of a higher acceptance angle 7.

[0058] FIG. 11 shows a preferred embodiment of the device 4 for non-contact optical recording of the papillary structure of the hand 3 or a part thereof. The device 4 has two projectors 25 for illuminating the hand with structured light and three cameras 2 for detecting the light diffusely reflected from the hand 3 or a part thereof. There is a substantially non-zero difference 17 between the distances 15, 16 from the lighting unit(s) 1 and the camera(s) 2 to the object plane 21.

[0059] FIG. 12 shows a block diagram of a configuration example, where data recording is requested by the arithmetic unit 29, which triggers a trigger signal on the data bus, causing the device 4 to project a stripe pattern onto the projector 25 as a special configuration of the lighting unit 1, and in synchronization therewith, an image of the hand 3 to be measured is recorded by the camera 2 together with the projected stripe pattern. This image is transferred via a further data bus to the data processing of the arithmetic unit 29, where the height determination and rotation determination of the hand positioning are performed, a correction determination is made based on these results, and this is provided to the user with feedback on the display unit 36 via a further data bus.

[0060] FIG. 13 shows an example flowchart of a method for position detection, where, after starting the method, reception of image data is brought about by the control of the camera 2, and then the step of transmitting the image data to the arithmetic unit 29 executes data processing for recognizing the position of the hand, where, in the case of an inaccurate hand positioning in the sense of an inaccurate distance 32, a correction of the position is requested, which is signaled to the user via the display unit 36. Then, another recording is started, and if the hand position is acceptable, the process of determining the exact position is completed, ensuring an error-free and high-resolution image recording of the papillary structure of the hand 3 or its individual fingers by an acceptable positioning of the hand 3 within the depth of field range 9.

[0061] FIG. 14 shows an example of a flowchart of a method for position recognition. Here, after starting the method, the trigger of camera 2 brings about the reception of image data. Then, as a result of the step of transmitting the image data to arithmetic unit 29, data processing for recognizing the position of the hand is performed. Here, in the case of inaccurate hand positioning in the sense of inaccurate distance 32, position correction is required, which is signaled to the user via display unit 36. Then, another recording is started. When the hand position is acceptable, the rotation of the hand is analyzed. If the hand positioning is inaccurate in the sense of inaccurate rotation 33, rotation correction is required, which is signaled to the user via display unit 36. Then, another recording is started. When the rotation of the hand is acceptable, the process of determining the accurate position is completed, and a high-resolution image recording of the papillary structure of hand 3 or a part thereof without errors is ensured by acceptable positioning of the hand within depth of field range 9.

[0062] FIG. 15 shows an example of the design of fingerprint recording device 4 having recess 30 on the upper surface facing the user for accurate hand positioning 31.

[0063] FIG. 16 shows accurate hand positioning 31, in which the hand or a part thereof is accurately placed between upper limit 8 of depth of field range 9 and lower limit 10 of depth of field range 9. Further, inaccurate hand positioning in the sense of inaccurate distance 32 of the hand or a part thereof is shown. Further, inaccurate hand positioning in the sense of inaccurate rotation 33 of hand 3 is shown.

[0064] FIG. 17 shows an example of the design of fingerprint recording device 4 having recess 30 attached to the upper surface facing the user and including feedback module 35 configured as display unit 36 (display) for accurate hand positioning 31.

Description of Reference Numerals

[0065] 1 Lighting unit 2 Camera 3 Hand (or a part thereof) 4 Fingerprint recording device 5 Deflection mirror 6 Contact area 7 Allowable angle 8 Upper limit of depth of field range 9 Depth of field range 10 Lower limit of depth of field range 11 Optical axis of illumination unit 12 Optical axis of camera 13 Field of view of illumination unit 14 Field of view of camera 15 Distance from illumination unit to object surface 16 Distance from camera to object surface 17 Difference in distance from camera to object surface and from illumination unit to object surface 18 Structure size of structured illumination on camera sensor 19 Structure size of structured illumination on light modulator of projector 20 Structure size of structured illumination on object surface 21 Object level 22 Effective focal length of camera lens 23 Effective focal length of illumination unit 24 Measurement depth range 25 Projector 26 Camera operating distance 27 Intermediate depth of field 28 Distance from illumination unit to intermediate plane of depth of field 29 Arithmetic unit 30 Concave part 31 Accurate hand positioning 32 Incorrect hand positioning in the sense of incorrect distance 33 Incorrect hand positioning in the sense of incorrect rotation 34 Image analysis 35 Feedback module 36 Display unit

Claims

1. A non-contact optical recording device for a papillary structure of a hand (3) or a part thereof, an illumination unit (1) having an optical modulator for illuminating the hand (3) or a part thereof with structured light, the camera (2) for detecting light from the illumination unit (1) diffusely reflected from the hand (3) or a part thereof on the object plane (21) of the camera (2), a calculation unit (29), and comprising: Using a determination method for determining the structure size of the structured light on the sensor of the camera (2) by image analysis (34), in relation to the depth of field range (9) of the camera (2), to determine the position of the hand (3) or a part thereof, there is a non-zero difference (17) between the distance (16) from the camera (2) to the object plane (21) along the optical axis (12) of the optical path of the camera (2) and the distance (15) from the illumination unit (1) to the object plane (21) along the optical axis (11) of the optical path of the illumination unit (1), The image analysis (34) is an analysis of the image recorded by the camera (2) with respect to the known structure size of the structured light irradiating the hand (3) or a part thereof on the optical modulator of the illumination unit (1), The calculation unit (29) calculates the position of the hand (3) or a part thereof by the determination method in relation to the depth of field range (9) of the camera (2), and calculates a fingerprint image having a papillary structure of the hand (3) or a part thereof. Device.

2. The operating distance (26) of the camera is at least 50 mm and at most 1500 mm, The device according to claim 1.

3. The distance (28) of the illumination unit (1) to the depth of field range (9) of the camera (2) is at least 50 mm and at most 1400 mm, The device according to claim 1.

4. The beam paths of the camera (2) and the illumination unit (1) are non-parallel along the optical axis (12) of the camera (2) and the optical axis (11) of the illumination unit (1). The apparatus according to claim 1.

5. The beam paths of the illumination unit (1) and the camera (2) are folded via a deflection mirror and do not take up space. The apparatus according to claim 4.

6. The illumination unit (1) has an emission light spectrum within the range of 350 nm to 1000 nm. The apparatus according to claim 1.

7. The illumination unit (1) has a two-dimensional intensity modulator that includes a lens on the front surface and a DLP, LCD, or LCoS system. The apparatus according to claim 1.

8. The illumination unit (1) has a two-dimensional intensity modulator that includes a diffraction element. The apparatus according to claim 1.

9. The illumination unit (1) has a two-dimensional intensity modulator that includes a lens on the front surface and a transmissive light image that rotates rigidly or is translatable. The apparatus according to claim 1.

10. There is additionally a feedback module (35) for outputting an acoustic, tactile, or visual signal or a combination thereof, by which the user can access information about the recording of the papillary structure of the hand, or additional information, in the case of a correction proposal for removing an inaccurate hand positioning (31), or an inaccurate hand positioning (32) in the sense of an inaccurate distance or an inaccurate hand positioning (33) in the sense of an inaccurate rotation. The apparatus according to any one of claims 1 to 9.

11. The feedback module (35) for generating a visual signal is a display unit (36) integrated within the device (4) for fingerprint recording. The device according to claim 10.

12. The feedback module (35) for generating a visual signal is an LED line integrated within an upper region of the device. The device according to claim 10.

13. A method for non-contact optical recording of the papillary structure of a hand (3) or a part thereof, wherein the hand (3) of the user is positioned within a measurement depth range (24) of a device (4) for fingerprint recording, Illuminating the hand (3) or a part thereof with structured light from an illumination unit (1) having an optical modulator; There is a non-zero difference (17) between a distance (16) from the camera (2) to an object plane (21) of the camera (2) along an optical axis (12) of an optical path of the camera (2) and a distance (15) from the illumination unit (1) to the object plane (21) along an optical axis (11) of an optical path of the illumination unit (1), Detecting, by a sensor of the camera, the structured light from the illumination unit diffusely reflected from the hand (3) or a part thereof as an image of an illumination pattern and transmitting the image to an arithmetic unit (29); Determining, in the arithmetic unit (29) by image analysis, a structure size of the structured light on the sensor of the camera (2); Calculating, in the arithmetic unit (29), a position of the hand (3) or a part thereof in relation to a depth of field range (9) of the camera (2) using a determination method for determining the structure size of the structured light on the sensor of the camera (2) by image analysis (34), The image analysis (34) is an analysis of an image recorded by the camera (2) with respect to a known structure size of the structured light irradiating the hand (3) or a part thereof on the optical modulator of the illumination unit (1), When the position is completely within the depth of field range (9) of the camera (2), calculating a fingerprint image of the hand (3) or a part thereof having a papillary structure A method comprising: **Claim 14**: The determination of the structure size of the structured light on the sensor of the camera (2) is made by image analysis (34) in the frequency space. The method according to claim 13. **Claim 15**: The determination of the accurate hand positioning (31) occurs via image analysis (34) in the sense of an inaccurate distance or an inaccurate rotation of the hand (3) with respect to the camera (2). The method according to claim 13. **Claim 16**: In the case of inaccurate hand positioning (32) in the sense of an inaccurate distance or inaccurate hand positioning (33) in the sense of an inaccurate rotation, a correction instruction is issued via a feedback module (35). The method according to claim 13.

Images