DESC:FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION: “COMPACT FINGER PRINT AND FINGER VEIN COMBINED SCANNER”
2. APPLICANTS:

(a) Name : Mantra Softech (India) Private Limited
(b) Nationality : Indian
(c) Address : B-203 Shapath Hexa, Opp. Gujarat High Court
S. G. Highway, Sola, Ahmedabad 380 060
PROVISIONAL
The following specification describes the invention. þ COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
[1] The present disclosure relates to biometric authentication device for combined fingerprint and finger vein imaging, and more particularly to an apparatus utilizing a selective coated cemented prism pair (1’) with a color glass filter having a central hole and a common focal plane array imaging detector for sequential or simultaneous capture of fingerprint and finger vein biometric data.
BACKGROUND
[2] Biometric authentication systems have become increasingly prevalent in security applications, utilizing unique physiological characteristics such as fingerprints and finger veins for individual identification and verification. Fingerprint recognition technology operates by capturing the ridge and valley patterns on the surface of a finger, typically using optical or capacitive sensing methods. Finger vein recognition technology captures the vascular patterns within the finger using near-infrared illumination that is absorbed by hemoglobin in the blood vessels, creating distinctive patterns for authentication purposes.
[3] Biometrics is a method of recognizing or authenticating using physical characteristics of an individual, such methods of biometrics may include fingerprint, face, finger vein, and signature recognition. Among these biometric identification methods, fingerprint identification is a technique for identifying an individual using a pattern obtained from a fingerprint image obtained using an optical camera or a semiconductor, while an finger vein recognition is a technique for identifying an individual using a vein pattern in a finger.
[4] Fingerprint acquisition devices are used in many fields in order to, for example, secure appliances, and secure buildings, control accesses, or control the identity of individuals. While data, information, and accesses protected by fingerprint sensors multiply, fingerprint acquisition devices are the target of significant fraud. The most current types of fraud are photocopies of fingers or of fingerprints or the reconstitution of fingers or of fingerprints in silicone, in latex, etc.
[5] Traditional biometric systems often employ separate imaging devices for different biometric modalities, resulting in increased system complexity, cost, and physical footprint. Conventional fingerprint scanners typically utilize frustrated total internal reflection (FTIR) principles with prism-based optical systems, while finger vein scanners employ transmission or reflection-based near-infrared imaging techniques. The integration of multiple biometric modalities into a single device presents challenges in optical design, as different wavelengths and imaging requirements must be accommodated.
[6] Existing dual-mode biometric systems face several technical limitations. One problem is the requirement for multiple imaging sensors and separate optical paths, which increases hardware costs and system complexity. The use of different sensors for fingerprint and vein imaging also introduces timing delays and synchronization issues when capturing biometric data sequentially.
[7] Another problem is the difficulty in achieving compact device designs while maintaining adequate image quality for both fingerprint and finger vein capture. Conventional systems often require separate illumination sources positioned at different locations, leading to larger device form factors that are not suitable for integration into portable electronic devices or space-constrained applications.
[8] A further problem exists in the optical design challenges associated with combining different wavelength requirements in a single imaging system. Fingerprint imaging typically uses visible light wavelengths, while finger vein imaging uses near-infrared wavelengths. Managing these different spectral requirements while maintaining proper focus and image quality across both modalities presents design complexities.
[9] The patent application number KR101147137B1 discloses a system consists of an infrared illuminating unit and a visible light illuminating unit that project light onto a user's finger. A camera captures both fingerprint and vein images by sensing the transmitted infrared and visible light through a movable filter. The camera uses separate imaging elements for infrared and visible light to generate the respective images. The infrared light is directed to the upper side of the finger and passes through the lower side, while a second infrared sensor and a visible light camera are positioned within the barrel to capture the images. The finger is positioned within a surrounding structure, with the system designed to detect both fingerprint and vein information.
[10] The system features two coupled lens barrels: one with a visible light camera for capturing fingerprint images and the other with an infrared camera for capturing vein images. An infrared illuminator lights the finger for vein detection. The finger is positioned at one end of the second barrel for both fingerprint and vein imaging. Such System can have interruptions caused by red light for fingerprint capturing and infrared light being used for vein capturing.
[11] Hence, it is needed to invent a biometric authentication device having an optical system for combined fingerprint and finger vein imaging with compact design and effective method.
OBJECTIVE OF THE INVENTION
[12] The object of the present invention is to provide a compact fingerprint and finger vein combined scanner with common imaging detector that overcomes the limitations of existing dual-mode biometric systems.
[13] Another object of the invention is to provide a single focal plane array imaging detector based optical system for combined fingerprint and finger vein imaging by utilizing a selective coated cemented prism pair (1’) in combination with a color glass filter having a central hole.
[14] Yet another object of the invention is to enable sequential operation to capture fingerprint and finger vein image data separately using a selective coated cemented prism pair (1’) with a combination of red and infrared LEDs that operate sequentially.
[15] A further object of the invention is to provide a compact optical design that eliminates the need for multiple imaging sensors and separate optical paths, thereby reducing hardware costs and system complexity.
[16] Still another object of the invention is to provide an aperture stop having a near infrared blocking color glass filter with a central air hole that maintains different optical beam aperture diameters for fingerprint and finger vein imaging modes to control defocus in finger vein imaging mode.
[17] Another object of the invention is to enable simultaneous acquisition of fingerprint and finger vein images when using a color pixelated detector array, where red wavelength sensitive pixels produce fingerprint images and near infrared sensitive pixels produce finger vein images simultaneously.
[18] Yet another object of the invention is to provide a selective interference coating on the cemented surface of the prism pair that transmits red LED wavelength for fingerprint imaging while enabling reflection of near infrared wavelength for finger vein imaging at different incidence angles.
[19] A further object of the invention is to provide a biometric authentication device that improves security and efficiency in identification systems while reducing the physical footprint and eliminating the need for multiple imaging devices.
SUMMARY
[20] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description.
[21] A compact fingerprint and finger vein combined scanner comprises a cemented prism pair including a first prism block and a second prism block joined by a selective interference coating that transmits red LED wavelength and reflects near-infrared wavelength at different incidence angles. Said system has a red LED to illuminate a finger placement surface on the first prism block for fingerprint imaging; near-infrared LEDs are positioned on side to illuminate the finger placement surface for finger vein imaging. Further, an imaging lens system comprising a First Imaging Lens and a Second Imaging Lens arranged in sequence to receive light from the cemented prism pair, with an aperture stop having a near-infrared blocking color glass filter with a central air hole, wherein the color glass filter transmits red LED wavelength and absorbs near-infrared wavelength, and the central air hole transmits all wavelengths. The system also comprises a two-dimensional imaging detector positioned at end of optical path to receive light through the imaging lens system and aperture stop.
[22] This configuration enables capturing of both fingerprint and finger vein biometric data using a single imaging detector, eliminating multiple sensors and reducing system complexity.
[23] The optical scanner operates in sequential mode wherein the red LED and near-infrared LEDs operate sequentially when using a monochrome imaging detector to capture fingerprint and finger vein images separately.
[24] The optical scanner operates in simultaneous mode wherein the red LED and near-infrared LEDs operate simultaneously when using a color pixelated imaging detector, wherein red wavelength sensitive pixels produce fingerprint images and near-infrared sensitive pixels produce finger vein images.
[25] The aperture stop maintains different optical beam aperture diameters for fingerprint and finger vein imaging modes, wherein the optical beam diameter in fingerprint mode is larger than in finger vein mode to control defocus.
[26] The two-dimensional imaging detector is selected from a charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) sensor configured as either a monochrome or color pixelated array.
BRIEF DESCRIPTION OF FIGURES
[27] Embodiments of the invention will be described, by way of example, with reference to the following drawings, in which:
[28] FIG. 1 illustrates a detailed cross-sectional schematic of the compact fingerprint and finger vein combined scanner showing the complete optical system architecture.
[29] FIG. 2 illustrates a comprehensive optical path diagram for the finger vein imaging mode of the system as claimed in FIG. 1, demonstrating the red LED illumination setup and the aperture light path configuration, according to the present disclosure.
[30] FIG. 3 illustrates a detailed optical path diagram for the fingerprint imaging mode of the system as claimed in FIG. 1, demonstrating the infrared LED illumination configuration and the central aperture light beam pathway through the optical system components, according to the present disclosure.
[31] FIG. 4 illustrates a detailed cross-sectional view of the aperture stop configuration showing the three concentric zones.
[32] Common reference numerals are used throughout the figures to indicate similar features.
DETAILED DESCRIPTION
[33] The following terminology and definitions are used throughout this disclosure to provide clarity and consistency in describing the compact fingerprint and finger vein combined scanner system.
[34] Fingerprint imaging may include the capture and analysis of ridge and valley patterns present on the surface of a finger. Fingerprint imaging may utilize optical techniques such as frustrated total internal reflection to detect contact areas between finger ridges and an optical surface.
[35] Finger vein imaging refers to the capture of vascular patterns within finger tissue using near-infrared illumination. The hemoglobin in blood vessels absorbs near-infrared light, creating distinctive shadow patterns that represent the internal vein structure. These patterns may provide subsurface biometric identification that is difficult to replicate or spoof.
[36] Cemented prism pair may include two optical prism blocks that are joined together with an optical adhesive or cement at their interface. The cemented interface may incorporate selective coatings that provide wavelength-dependent transmission and reflection properties for different optical wavelengths.
[37] Selective interference coating refers to a thin-film optical coating applied to surfaces that exhibits wavelength-selective properties. Such coatings may transmit certain wavelengths while reflecting others, and the transmission and reflection characteristics may vary depending on the angle of incidence of the light.
[38] Frustrated total internal reflection (FTIR) may include an optical phenomenon that occurs when light traveling through a medium encounters an interface where total internal reflection would normally occur, but the presence of a second medium in close contact disrupts this reflection. In fingerprint imaging, FTIR may be used to detect areas where finger ridges make direct contact with an optical surface.
[39] Aperture stop refers to an optical element that controls the diameter of the light beam passing through an optical system. The aperture stop may determine the amount of light that reaches the imaging detector and can influence the depth of field and image quality characteristics.
[40] Color glass filter may include an optical filter made from colored glass that selectively transmits certain wavelengths while absorbing others. In this disclosure, color glass filters may be used to separate red wavelengths from near-infrared wavelengths in the optical path.
[41] Focal plane array refers to a two-dimensional array of photo-detectors arranged in a grid pattern to capture optical images. The focal plane array may be positioned at the focal plane of an optical system to record spatial intensity distributions of light.
[42] Sequential operation may include a mode of operation where different illumination sources are activated at different times to capture separate images. In sequential mode, fingerprint and finger vein images may be captured in temporal sequence using the same imaging detector.
[43] Simultaneous operation refers to a mode of operation where multiple illumination sources operate concurrently. When using color pixelated detectors, simultaneous operation may enable concurrent capture of fingerprint and finger vein images through wavelength-selective pixel response.
[44] Monochrome detector may include an imaging sensor that responds to light intensity without distinguishing between different wavelengths. Monochrome detectors may capture grayscale images and typically require sequential illumination for multi-wavelength applications. Examples of monochrome detectors include monochrome CCD sensors, monochrome CMOS sensors, and silicon photodiode arrays.
[45] Color pixelated detector refers to an imaging sensor with pixels that have wavelength-selective sensitivity. Color detectors may include pixels sensitive to different spectral ranges, enabling simultaneous capture of images at different wavelengths. Examples of color pixelated detectors include Bayer pattern CCD sensors, Bayer pattern CMOS sensors, RGB CMOS image sensors, and multi-spectral imaging arrays with red, green, blue, and near-infrared sensitive pixels.
[46] Near-infrared wavelength may include electromagnetic radiation with wavelengths typically ranging from approximately 700 nm to 1400 nm. In finger vein imaging applications, near-infrared wavelengths around 840 nm may be used for optimal penetration through finger tissue.
[47] Red wavelength refers to visible light wavelengths typically ranging from approximately 620 nm to 750 nm. In fingerprint imaging applications, red wavelengths around 660 nm may be used for optimal surface illumination and contrast.
[48] FIG. 1 illustrates an optical diagram (1) of a compact fingerprint and finger vein combined scanner system. The optical diagram (1) shows a complete dual-mode biometric imaging architecture that enables capture of both fingerprint and finger vein patterns through a single optical path configuration.
[49] The system comprises a cemented prism pair (1’) configuration including a second prism block (2) and a first prism block (3). The second prism block (2) and the first prism block (3) are optically coupled through an interference coating (7) positioned at the cemented interface between the prism blocks. The interference coating (7) provides wavelength-selective optical properties that operate with different incidence angles for transmission and reflection paths to enable dual-mode operation of the biometric scanner.
[50] A finger placement surface (6) is positioned on top of the first prism block (3) where a user's finger contacts the optical system during biometric scanning operations. The finger placement surface (6) provides the interface for both fingerprint ridge pattern detection and finger vein pattern illumination.
[51] The illumination subsystem includes a red LED (4) and infrared LEDs (5) that provide wavelength-specific illumination for the dual biometric imaging modes. The red LED (4) operates at a specific wavelength of 660 nm for fingerprint illumination and is positioned to direct light toward the finger placement surface (6) and the first prism block (3). The infrared LEDs (5) are arranged to provide near-infrared illumination at 840 nm for finger vein imaging through the finger tissue.
[52] An imaging lens system (8) comprising a First imaging lens (8a) and a Second imaging lens (8b)arranged in sequence is positioned in the optical path to focus light from the prism assembly onto an imaging detector (10). The First imaging lens (8a) and Second imaging lens (8b)are specifically optimized for fingerprint imaging performance to provide optimal image quality for ridge pattern detection. An aperture filter (9) is positioned between the First imaging lens (8a) and the Second imaging lens (8b)such as it focuses optical beam on the imaging detector (10) and helps control the optical beam characteristics for each imaging mode.
[53] The aperture filter (9) includes three distinct zones that provide wavelength-selective filtering and aperture control. Zone C provides mounting and optical blocking for all wavelengths around the outer perimeter. Zone A contains a color glass filter for wavelength selection that specifically transmits 660 nm wavelength from the red LED (4) and absorbs 840 nm wavelength from the infrared LEDs (5). Zone B comprises an air hole at the center that allows transmission of all wavelengths including both red and infrared illumination. The aperture filter (9) configuration enables the optical beam diameter in fingerprint mode to be larger than in finger vein mode to control defocus in finger vein imaging.
[54] The imaging detector (10) comprises a two-dimensional photodiode array that can be implemented as either a CCD or CMOS sensor. The imaging detector (10) captures both fingerprint and finger vein image data through the common optical path configuration.
[55] The optical diagram (1) shows an optical path of the finger print mode (1A) and an optical path of the finger vein mode (1B) that demonstrate the dual-mode operation capabilities. An aperture light path (9a) represents light transmission through both the color glass filter zone and the central air hole zone of the aperture filter (9). A central aperture light beam (9b) represents light transmission through only the central air hole zone of the aperture filter (9), providing the smaller aperture diameter for finger vein imaging mode.
[56] FIG. 2 illustrates the finger vein imaging mode operation where the infrared LEDs (5) provide illumination for capturing vein patterns within finger tissue. During finger vein imaging mode, the infrared LEDs (5) operate at a wavelength of 840 nm to enable transmission of light through the finger tissue positioned on the finger placement surface (6).
[57] The optical path for finger vein imaging follows a transmission and reflection sequence through the prism system. Light from the infrared LEDs (5) passes through the finger tissue and enters the first prism block (3). The infrared illumination then transmits through the interference coating (7) at the interface between the first prism block (3) and the second prism block (2). The light continues through the second prism block (2) and reflects from the bottom surface of the second prism block (2).
[58] The reflected light travels back toward the interference coating (7), where the light undergoes reflection due to the different incidence angles encountered in the reflection path compared to the initial transmission path. The interference coating (7) enables this dual-mode operation by providing wavelength-selective properties that accommodate both transmission and reflection of the infrared illumination at different optical angles.
[59] The central aperture light beam (9b) represents the optical path configuration specific to finger vein imaging mode. The central aperture light beam (9b) passes through only the central air hole zone of the aperture filter (9), which provides a smaller aperture diameter compared to fingerprint imaging mode. The reduced aperture diameter controls defocus effects during finger vein imaging since the imaging lens system (8) comprising First imaging lens (8a) and Second imaging lens (8b)is optimized for fingerprint imaging performance.
[60] The finger vein pattern captured through this optical configuration reaches the imaging detector (10) through the imaging lens system (8). When the imaging detector (10) comprises a monochrome array, the infrared LEDs (5) and the red LED (4) operate sequentially in time domain to capture fingerprint and finger vein images separately through time-division multiplexing, enabling temporal separation of the two biometric imaging modes.
[61] As used herein, time-division multiplexing refers to a technique where the red LED (4) and near-infrared LED (5) are activated sequentially at different time intervals rather than simultaneously. In some aspects, the red LED (4) may be activated first to illuminate the finger placement surface (6) for fingerprint capture using frustrated total internal reflection, followed by activation of the near-infrared LED (5) for finger vein imaging through tissue transmission. The monochrome imaging detector (10) captures separate images during each illumination period, allowing the system to distinguish between fingerprint and finger vein data based on the timing of LED activation. This approach may be particularly suitable when using a single monochrome detector array that cannot differentiate between wavelengths based on pixel sensitivity alone.
[62] FIG. 3 illustrates the fingerprint imaging mode operation where the red LED (4) provides illumination for capturing fingerprint ridge and valley patterns. During fingerprint imaging mode, the red LED (4) operates at the 660 nm wavelength to illuminate the finger placement surface (6) and the contact interface between finger tissue and the first prism block (3).
[63] The optical path configuration for fingerprint imaging utilizes frustrated total internal reflection principles to enable detection of fingerprint surface features. When a finger contacts the finger placement surface (6), the fingerprint ridges make direct contact with the surface of the first prism block (3), while the valleys remain separated by air gaps. The red LED (4) directs illumination toward the contact interface, where light undergoes frustrated total internal reflection at locations where fingerprint ridges contact the prism surface.
[64] Light from the red LED (4) scatters from the fingerprint ridge areas that are in direct contact with the first prism block (3). The scattered light passes from the first prism block (3) to the second prism block (2) through the interference coating (7). The interference coating (7) transmits the 660 nm wavelength from the red LED (4), allowing the fingerprint image information to pass through the cemented prism interface.
[65] The aperture light path (9a) represents the optical path configuration specific to fingerprint imaging mode. The aperture light path (9a) passes through both the color glass filter zone and the central air hole zone of the aperture filter (9). The broader aperture configuration provided by the aperture light path (9a) enables capture of fingerprint ridge and valley patterns with optimal image quality since the imaging lens system (8) comprising first imaging lens (8a) and second imaging lens (8b) is optimized for fingerprint imaging performance.
[66] The transmitted light continues through the imaging lens system (8) and the aperture filter (9) before reaching the imaging detector (10). The imaging detector (10) records the fingerprint ridge and valley pattern information as variations in light intensity corresponding to the contact and non-contact areas between the finger surface and the first prism block (3).
[67] When the imaging detector (10) comprises a color pixelated array, red wavelength sensitive pixels in the color detector array produce fingerprint images. The red wavelength sensitive pixels respond specifically to the 660 nm illumination from the red LED (4), enabling capture of fingerprint pattern data. In color detector configurations, near infrared sensitive pixels produce finger vein images simultaneously, allowing concurrent capture of both biometric modalities through wavelength-selective pixel response characteristics.
[68] In another embodiment, an additional lens can be attached at a bottom of the second prism block (2) to facilitate zoom in and zoom out function for optimizing scanning area. The additional lens provides enhanced optical magnification control that can improve image quality for finger vein detection applications.
[69] FIG. 4 illustrates a detailed view of the aperture filter (9) configuration that provides wavelength-selective filtering and beam diameter control for the dual-mode biometric imaging system. The aperture filter (9) comprises a circular configuration with three distinct concentric zones that enable selective optical control for fingerprint and finger vein imaging modes through wavelength-division multiplexing. As used herein, wavelength-division multiplexing refers to a technique where the red LED (4) and near-infrared LED (5) operate concurrently, with the system distinguishing between the two biometric modalities based on the different wavelengths of light rather than timing.
[70] The aperture filter (9) includes an outermost Zone C defined as the area between circle c and circle a. Zone C provides mounting functionality for the color glass filter assembly and optically blocks all wavelengths of light from passing through the outer perimeter region. Zone C serves as a structural support region that maintains the mechanical integrity of the aperture filter (9) within the optical system.
[71] Zone A comprises the annular area between circle a and circle b and contains a color glass filter element that provides wavelength-selective transmission properties. The color glass filter in Zone A specifically transmits the 660 nm wavelength emitted by the red LED (4) while absorbing the 840 nm wavelength emitted by the infrared LEDs (5). The wavelength-selective properties of Zone A enable beam aperture control of the fingerprint imaging wavelength from the finger vein imaging wavelength within the optical path.
[72] Zone B comprises the innermost circular area defined by circle b and consists of an air hole that extends through the center of the aperture filter (9). Zone B allows transmission of all wavelengths including both the 660 nm red illumination and the 840 nm infrared illumination. The air hole configuration of Zone B provides an unfiltered optical path that accommodates both biometric imaging wavelengths.
[73] The three-zone configuration of the aperture filter (9) enables control of optical beam diameter for each imaging mode. During fingerprint imaging mode, light passes through both Zone A and Zone B, creating a larger effective aperture diameter. During finger vein imaging mode, light passes through Zone B alone, creating a smaller effective aperture diameter that corresponds to the central air hole area.
[74] The differential beam diameter control provided by the aperture filter (9) addresses the optical performance requirements of the dual-mode system. The larger beam diameter during fingerprint imaging mode provides optimal light collection and image quality since the imaging lens system (8) comprising first imaging lens (8a) and second imaging lens (8b) is optimized for fingerprint imaging performance. The smaller beam diameter during finger vein imaging mode controls defocus effects that would otherwise occur due to the lens optimization for fingerprint imaging.
[75] In another embodiment, this approach may utilize a color pixelated detector array where different pixel types have varying sensitivities to red and near-infrared wavelengths. The aperture filter (9) may facilitate this process by selectively transmitting red wavelength light through its wavelength-selective filter portion while allowing both red and near-infrared light to pass through its central opening. The selective interference coating (7) may further enable wavelength-based separation by transmitting and reflecting different wavelengths at various incidence angles, allowing simultaneous capture of both fingerprint and finger vein images in a single acquisition cycle.
[76] The compact fingerprint and finger vein combined scanner provides cost reduction through single detector use by eliminating the need for separate imaging systems for each biometric modality. The combined scanner architecture utilizes a common focal plane array detector that captures both fingerprint ridge patterns and finger vein structures through a single optical path, reducing the total number of components required for dual biometric authentication.
[77] The dual-mode operation capability accommodates different implementation requirements through monochrome and color detector configurations. Monochrome detector implementations provide sequential biometric capture with temporal separation between fingerprint and finger vein imaging, while color detector implementations enable simultaneous biometric capture through wavelength-selective pixel response characteristics.
[78] Improved security through dual biometric authentication enhances the reliability of user identification compared to single-modality biometric systems. Fingerprint recognition provides surface-level biometric identification through ridge and valley patterns, while finger vein recognition provides subsurface biometric identification through vascular structures within finger tissue. The combination of surface and subsurface biometric characteristics creates a multi-factor authentication approach that increases the difficulty of spoofing or circumventing the security system.
[79] The compact form factor enables integration into portable devices and space-constrained applications where traditional separate biometric scanners would be impractical. The cemented prism pair (1’) configuration and common optical path architecture reduce the overall system volume compared to implementations that require separate optical assemblies for each biometric modality.
[80] Elimination of multiple imaging paths simplifies the optical design and reduces mechanical complexity compared to traditional separate biometric scanners. The combined scanner architecture consolidates both biometric imaging functions into a single optical path that shares common optical elements, reducing the number of precision-aligned components and mechanical interfaces required for proper system operation.
[81] Enhanced authentication reliability results from the complementary nature of fingerprint and finger vein biometric characteristics. Fingerprint patterns can be affected by surface conditions such as moisture, dirt, or temporary skin damage that may reduce recognition accuracy. Finger vein patterns remain stable and unaffected by surface conditions since the vascular structures are located within the finger tissue. The availability of both biometric modalities provides redundancy that maintains authentication capability when one modality experiences reduced performance due to environmental or physiological factors.
[82] Reduced system complexity compared to traditional separate biometric scanners decreases manufacturing requirements and maintenance considerations. The shared optical components and common detector configuration reduce the number of calibration procedures required during manufacturing and the number of potential failure points during operation. The wavelength-selective filtering and sequential or simultaneous operation modes eliminate the need for complex mechanical switching mechanisms or movable optical elements.
[83] Power consumption benefits result from the shared optical components and detector configuration compared to separate biometric scanning systems. The common imaging detector (10) eliminates the power requirements associated with operating multiple detector arrays, while the shared optical path reduces the total illumination power required for biometric image capture. The sequential operation mode for monochrome detectors enables power management strategies that activate illumination sources only when needed for each specific biometric modality.
[84] Features of any of the examples or embodiments outlined above may be combined to create additional examples or embodiments without losing the intended effect. It should be understood that the description of an embodiment or example provided above is by way of example only, and various modifications could be made by one skilled in the art. Furthermore, one skilled in the art will recognise that numerous further modifications and combinations of various aspects are possible. Accordingly, the described aspects are intended to encompass all such alterations, modifications, and variations that fall within the scope of the appended claims.

LIST OF REFERENCE NUMERALS
1 Optical Diagram
1’ Cemented Prism Pair
1a Optical Path of the Finger Print Mode
1b Optical Path of the Finger Vein Mode
2 Second Prism Block
3 First Prism Block
4 Red LED
5 Infrared LEDs
6 Finger Placement Surface
7 Interference Coating
8a First Imaging Lens
8b Second Imaging Lens
9 Aperture Filter
9a Aperture Light Path
9b Central Aperture Light Beam
10 Imaging Detector
,CLAIMS:WE CLAIM:
1. A compact fingerprint and finger vein combined scanner comprising:
a cemented prism pair (1’) comprising a first prism block (3) and a second prism blocks (2);
a selective interference coating (7) positioned between the first prism block (3) and the second prism block (2), the selective interference coating (7) configured to transmit red wavelength light and reflect near-infrared wavelength light at different incidence angles;
a red LED (4) positioned to illuminate a finger placement surface (6) on the first prism block (3);
at least one near-infrared LED (5) positioned to illuminate the finger placement surface (6);
an imaging lens system (8) involving a first Imaging Lens (8a) and a second imaging lens (8b) arranged in sequence to receive light from the cemented prism pair (1’);
an aperture filter (9) positioned between the imaging lens system (8) and an imaging detector (10), the aperture filter (9) involving a wavelength-selective filter that transmits red wavelength light and absorbs near-infrared wavelength light, and a central opening that transmits both red and near-infrared wavelength light; and
a two-dimensional imaging detector (10) positioned to receive light through the imaging lens system (8) and the aperture filter (9).
2. The system as claimed in claim 1, wherein the three concentric zones comprising:
zone C is an outermost zone that optically blocks all wavelengths and provides mounting functionality;
zone A is an intermediate zone containing the wavelength-selective filter; and
zone B an innermost zone containing the central opening.
3. The system as claimed in claim 1, wherein the red LED (4) and the at least one near-infrared LED (5) are configured to operate in a temporally sequential manner when the imaging detector (10) comprises a monochrome detector array, thereby enabling distinct capture of fingerprint and finger vein biometric data through time-division multiplexing.
4. The system as claimed in claim 1, wherein the red LED (4) and the at least one near-infrared LED (5) are configured to operate concurrently when the imaging detector (10) comprises a color pixelated detector array, thereby facilitating simultaneous acquisition of dual biometric modalities through wavelength-division multiplexing.
5. The system as claimed in claim 4, wherein red wavelength sensitive pixels in the color pixelated detector array produce fingerprint images and near-infrared wavelength sensitive pixels in the color pixelated detector array produce finger vein images.
6. The system as claimed in claims 1 to 5, wherein fingerprint imaging utilizes frustrated total internal reflection at the finger placement surface (6).
7. The system as claimed in claims 1 to 6, wherein finger vein imaging utilizes transmission of near-infrared light through finger tissue and reflection within the cemented prism pair (1’).
8. The system as claimed in claims 1 to 7, wherein the selective interference coating (7) enables transmission and reflection at different incidence angles for dual-mode operation.
9. The system as claimed in claims 1 to 8, further comprising an additional lens attached to the second prism block (2) to provide zooming functionality, wherein the scanner provides dual biometric authentication through combined fingerprint and finger vein recognition having a compact form factor suitable for integration into portable electronic devices.
10. A method of combined fingerprint and finger vein biometric scanning comprising:
a. positioning a finger on a finger placement surface (6) of a first prism block (3) in a cemented prism pair (1’) comprising the first prism block (3) and a second prism block (2) joined by a selective interference coating (7);
b. illuminating the finger placement surface (6) with a red LED (4) to capture fingerprint ridge and valley patterns and at least one near-infrared LED (5) to capture finger vein patterns;
c. directing light from the cemented prism pair (1’) through an imaging lens system (8) consisting a First imaging lens (8a) and a Second imaging lens (8b)arranged in sequence;
d. filtering the light through an aperture filter (9) involving a wavelength-selective filter that transmits red wavelength light and absorbs near-infrared wavelength light, and a central opening that transmits both red and near-infrared wavelength light; and
e. capturing both fingerprint and finger vein images through a two-dimensional imaging detector (10).
11. The method as claimed in claim 10, further comprising actuating the red LED (4) and the at least one near-infrared LED (5) in a temporally sequential manner when the imaging detector (10) comprises a monochrome detector array, thereby enabling time-division multiplexed acquisition of distinct biometric modalities.
12. The method as claimed in claim 10, further comprising actuating the red LED (4) and the at least one near-infrared LED (5) concurrently when the imaging detector (10) comprises a color pixelated detector array, thereby facilitating wavelength-division multiplexed capture of dual biometric data streams.
13. The method as claimed in claim 10 and 12, wherein red wavelength sensitive pixels in the color pixelated detector array produce fingerprint images and near-infrared wavelength sensitive pixels in the color pixelated detector array produce finger vein images simultaneously.
14. The method as claimed in claim 10, wherein capturing fingerprint images utilizes frustrated total internal reflection at the finger placement surface (6) and capturing finger vein images utilize transmission of near-infrared light through finger tissue and reflection within the cemented prism pair (1’).
15. The method as claimed in claim 10, wherein the selective interference coating (7) transmits red wavelength light and reflects near-infrared wavelength light at different incidence angles.

Dated this on 24th September, 2025.