Spectroscopic image processing method and dual-channel spectrometer systems for forensic and marker analyses

Abstract

The invention relates to a spectroscopic imaging and spectrometer system comprising at least two channels, the system being connectable to smartphones. The system is configured to simultaneously determine the optical properties, including reflectance, transmittance, color, and luminescence characteristics, of solids, liquids, and gases. The invention is particularly advantageous for forensic investigations and applications requiring the use of encrypted markers. The system operates by splitting the image of an object into two parts by means of a prism and subsequently employing optical filters and diffraction gratings. Furthermore, the system incorporates software compatible with external devices such as smartphones or computers. Said software enables the cameras of a smartphone to function as a spectrometer, thereby allowing spectra to be acquired through high-resolution imaging.

Description

[0001] DESCRIPTION

[0002] SPECTROSCOPIC IMAGE PROCESSING METHOD AND DUAL-CHANNEL

[0003] SPECTROMETER SYSTEMS FOR FORENSIC AND MARKER ANALYSES

[0004] Technical Field

[0005] The invention relates to a smart, dual-channel, user-friendly, environmentally friendly, and low-cost spectroscopic image processing method and spectrometer system, in the form of a handheld device also usable with smartphones, designed for the simultaneous detection of the optical properties (reflectance, transmittance, color, and luminescence characteristics) of solids, liquids, and gases.

[0006] The invention also relates to a next-generation spectrometric method and spectrometer system capable of determining the optical coefficients (refractive index and absorption coefficient) of solids, liquids, and gases.

[0007] The invention relates to a spectroscopic image processing method and spectrometer system for the simultaneous determination of the optical coefficients and optical properties of an object (surface) by splitting its image with a prism-like image duplicator and passing it through optical elements such as mirrors, lenses, slits, optical filters, and transmissive / reflective diffraction gratings, using suitable software.

[0008] The invention also relates to a spectroscopic image processing method and spectrometer system that, while having many different application areas, can be particularly used for the simultaneous determination of the optical properties of surfaces embedded with encrypted markers (such as paints or nanoparticle-like markers) requiring forensic or privacy-sensitive analysis.

[0009] The invention also relates to software capable of detecting optical properties.

[0010] Prior Art

[0011] Various solutions exist for determining the optical properties of solids, liquids, and gases. These are generally performed using expensive testing devices under laboratory conditions. The process is relatively cumbersome and time-consuming, involving separate procedures. For example, determining reflectance, transmittance, color, and luminescence properties with a spectrometer requires separate measurements using specific attachments. Such devices typically operate with the assistance of a computer and appropriate software. However, they are not practical for everyday use, are time-consuming, and expensive. Currently, commercially available spectrometer-based devices can measure the reflectance, transmittance, color, and luminescence properties of solids, liquids, and gases. However, these devices cannot split the image of an object for comparative analysis, cannot determine optical properties simultaneously, do not perform image processing, and are not compatible with smartphones.

[0012] Currently, commercially available spectroscopic designs that can be coupled with smartphones exist. However, in these designs, the object image is not split, and no image processing is performed. They are not suitable for forensic and marker analyses, as knowing the optical properties of the examined region is critically important. Determining the optical properties of the examined region can only be achieved with dual-channel spectroscopic methods, where one channel is used as a reference channel providing the actual image of the object. In specialized forensic and marker analyses, it is essential to identify the examined region and determine its optical properties. Therefore, the designed dual-channel spectrometer systems are user-friendly, low-cost, compatible with smartphones, and provide accurate information about the examined region.

[0013] US2004125371A1 discloses a system with multiple input channels that provides simultaneous spectral analysis across different spectral ranges. The system uses vertically and horizontally arranged input slits on a single sensor to achieve high-resolution imaging. This setup can operate with both visible and invisible light, such as near-infrared (NIR) and ultraviolet (UV) light, making it versatile for various applications, including environmental monitoring and biomedical imaging.

[0014] US10337841B2 discloses a spectrometer system that provides phase-sensitive detection in parallel channels. The system uses a combination of a light deflector and a high-resolution spectrometer to separate and detect light wavelengths with high precision. The design enables faster data acquisition and is suitable for various spectrometric analyses, including optical spectroscopy and Raman spectroscopy. This is particularly useful for applications requiring detailed spectral information and high sensitivity. US7382498B1 discloses a spectrometer featuring a common objective lens and a dual-slit optimized for different wavelengths. The system uses a double -pass reflective triplet and a beam splitter to direct light to different detectors, enabling multi-wavelength analysis simultaneously. This design enhances the spectrometer’s ability to analyze different materials based on their spectral properties, which is beneficial for applications such as materials science and forensic analysis.

[0015] US2015238135A1 discloses a device for detecting tissue anomalies. The device’s head includes separate optical paths for illumination, imaging, and light data collection. The use of a common tube at the endpoints of these optical paths is mentioned, but its internal structure and mode of operation are not defined. The use of a prism is mentioned in relation to the spectral separation of light.

[0016] CN 106323909A discloses a portable spectrometer. The device includes an arrangement with a slit (7) followed by a diffraction grating (14) between the input and the sensor. A filter (13) may also be positioned between the slit and the diffraction grating. Light sources directed at the target area are also described. The device can perform transmittance and reflectance measurements.

[0017] EP0498644A1 discloses a spectral analyzer. It discloses applications in which light from a slit passes through a reflective diffraction grating, as well as implementations that provide two-dimensional addressing to obtain information about the spatial distribution of the light.

[0018] CN208818644U discloses a portable analyzer. The use of light sources and an aperture in the input section is also disclosed.

[0019] However, in the systems and methods of the prior art, it is not possible to simultaneously determine the optical properties of a specific region, display them on a screen in real time, and examine them comparatively with the inspected area. Therefore, there is a need to develop a spectroscopic image analysis system and method for detailed examination of surfaces particularly forensic and marker-coated surfaces (or mixed if liquid) by splitting the object image into two using a prism-like image duplicator. Objectives and Brief Description of the Invention

[0020] The object of this invention is to develop a spectroscopic and image analysis system and method for determining the optical properties of solids and liquids processed with encrypted markers.

[0021] Another object of this invention is to develop a spectrometer-based image analysis system and method for determining the optical properties of solids and liquids for use in forensic cases, such as signature forgery, counterfeit passports, counterfeit money, and fingerprints.

[0022] Another object of this invention is to develop a spectrometer-based image analysis system and method for determining the optical properties of surfaces in medical applications (such as color measurement in urine test strips) or agricultural products (such as detection of pesticides), which also require the measurement of other optical phenomena like color.

[0023] While achieving these objectives, the object is also to provide a system that is practical, low- cost, mountable on smartphones, portable, and user-friendly.

[0024] Another object of this invention is to develop a spectrometer with two channels, which can be used separately and are suitable for spectroscopic measurements and image processing (spatial measurements).

[0025] To achieve all the objectives mentioned above and those arising from the detailed description below, the present invention, unlike other spectroscopic methods and commercially available spectrometers, is designed particularly for forensic and marker -based analyses. It involves splitting the image from an object into two channels using a prism, processing the image with the necessary optical components (mirrors, lenses, filters, diffraction gratings, etc.), displaying it simultaneously on a peer device, and determining optical properties such as image spectrum, luminescence characteristics, optical coefficients, and color properties using the implemented software.

[0026] Electromagnetic waves (hereinafter referred to as 'image') reflected from or transmitted through an object carry information about the optical properties of that object. If the image is duplicated two or more times using a prism (or an equivalent optical component), this allows for more detailed analysis, saves time, and increases reliability because the examined region remains the same. In Figure l.a, the image emitted from an illuminated object is first split into two channels (first channel and second channel) using a prism (or an equivalent optical component). In the first channel, the image taken from one surface of the prism passes through a slit via a parabolic mirror and is transmitted through the appropriate optical filter, lens, and diffraction grating before being projected onto a screen with the help of an imaging system such as a camera. In the second channel, the image taken from the other surface of the prism is optionally passed through different optical filters and projected onto the same screen. Through the first channel, the image of the object passing through the narrow slit is separated into wavelengths (spectra) and projected onto the screen with the assistance of a camera. With the help of software and appropriate illumination, this spectrum is used to determine the reflectance, absorption, transmittance, and color properties of the examined region (object). When a suitable optical filter is applied, the luminescence spectrum of the examined region can also be obtained. In the second channel, the image of the object (examined region) is projected onto the screen using a camera. The image obtained from the object in the second channel, when illuminated with light of different wavelengths and passed through various filters, allows detailed examination of the spatial distribution of both the image and its luminescence properties. The fact that the images in the first and second channels correspond to the same object (same determined region / area) provides accurate information, which is particularly valuable in forensic procedures and analyses of marker-labeled regions.

[0027] In Figure l.b, the image emitted from an illuminated object is first split into two channels (hereinafter referred to as first channel and second channel) using a prism (or an equivalent optical component). In the first channel, the incoming image is first passed through a slit and then separated into its spectrum (wavelengths) using a reflective diffraction grating. The spectrally separated image, after passing through an optical filter and lens, reaches a camera (i.e. smartphone camera) for processing. In the second channel, the image obtained from the other surface of the prism passes through optical filters, as in Figure l.a, and reaches the smartphone camera.

[0028] In Figure 2, the system is designed in a vertical position to facilitate ease of use for the same purpose. While Figures l.a and l.b are very similar to Figure 2, there are minor differences in the placement and types of optical components used. Figure 3 shows a design related to the positioning of the illumination system for transmittance-based measurements. This design can also be used in conjunction with the applications described in the other figures.

[0029] Detailed Description of the Invention

[0030] The spectroscopic image processing method and dual-channel spectrometer systems, developed to achieve the objectives of this invention particularly for forensic and marker applications are shown in the accompanying figures.

[0031] The Figures;

[0032] Figure l.a: Schematic view of the horizontal-position dual-channel spectrometer system (with the slit at the rear).

[0033] Figure l.b: Schematic view of the horizontal-position dual-channel spectrometer system (with the slit at the front).

[0034] Figure 2: Schematic view of the vertical-position dual-channel spectrometer system.

[0035] Figure 3: Schematic view of input section of the system, with the illumination unit positioned behind the object for transmittance-based measurements.

[0036] The components shown in the figures are individually numbered, and the corresponding references are provided below.

[0037] 1. Object

[0038] 2. LEDs with different wavelengths

[0039] 3. Diaphragm

[0040] 4. Image

[0041] 5. Image duplicator

[0042] 6. Elliptical mirror

[0043] 7. Slit

[0044] 8. Optical filter

[0045] 9. Transmissive diffraction grating

[0046] 10. Reflective diffraction grating

[0047] 11. Beam-collecting lens 12. First channel

[0048] 13. Second channel

[0049] 14. First sensor

[0050] 15. Second sensor

[0051] 16. External image processing unit

[0052] The invention relates to a dual-channel spectrometer, which can be used in marker detection and forensic applications and is operable in a horizontal position. The spectrometer essentially comprises: a body comprising a first channel (12) (first optical path) and a second channel (13) (second optical path),

[0053] Light sources (2), selected from LEDs or lasers of different wavelengths, are mounted on the body and oriented such that they are directed toward the target object (1) through the body, thereby illuminating said object (1) across the ultraviolet, visible, and infrared regions of the electromagnetic spectrum, (light sources such as lasers of different wavelengths) an image duplicator (5) located within the body, which splits the light received from the object (1) into two beams and directs them to the first channel (12) and the second channel (13), a first image sensor (14) and a second image sensor (15) positioned respectively on the first channel (12) and the second channel (13), a slit (7) and a diffraction grating on the first channel (12), arranged sequentially from the image duplicator (5) toward the first image sensor (14), a first optical filter (8) positioned on the first channel (12) between the slit (7) and the first image sensor (14), a second optical filter (8) positioned on the second channel (13) between the image duplicator (5) and the second image sensor (15).

[0054] The image duplicator (5) is preferably a prism.

[0055] In the embodiments of the invention shown in Figures La and Lb, the second channel (13) is aligned with one output direction of the image duplicator (5), while the first channel (12) intersects at an angle with the other output direction of the image duplicator (5). In these embodiments, at least one reflector is provided at the intersection point to direct light into the first channel (12). The reflector may be an elliptical mirror (6) or a reflective diffraction grating (10). When the reflector is an elliptical mirror (6), the diffraction grating used in the first channel (12) is a transmissive diffraction grating (9).

[0056] In the embodiment of the invention shown in Figure 2, the first channel (12) and the second channel (13) are aligned with the output directions of the image duplicator (5). In this case, the diffraction grating used in the first channel (12) is a transmissive diffraction grating (9).

[0057] The spectrometer of the invention preferably also comprises a diaphragm (3) that allows only light coming from the targeted object (1) to pass through. This enables measurements to be made without being affected by other surrounding light sources or unwanted reflections. The diaphragm (3) may have an adjustable aperture.

[0058] In the first channel (12), the rays passing through the slit (7) are diffracted and subsequently separated according to their wavelengths by the transmissive diffraction grating (9). Thus, spectrometric measurements are performed in the first channel (12), while image processing operations are carried out in the second channel (13). In both channels, the optical filters (8) transmit light according to a specific rule, thereby enabling the selection of the properties of the light to be analyzed. Furthermore, at necessary positions, for example, in the first channel (12) before the first sensor (14), at least one beam-collecting lens (11) is provided for focusing the image.

[0059] The spectrometer according to the invention may include an image processing unit that processes the data obtained from the image sensors, or preferably, at least one transmission device to transmit the acquired data to an external image processing unit (16), such as a computer or smartphone. The transmission device is preferably capable of wireless data transmission.

[0060] In one embodiment of the invention, instead of the first sensor (14) and the second sensor (15), a mount is provided for two of the cameras of a smartphone with multiple cameras, or a mount for two webcams connected to a computer. In this way, the cameras of the smartphone or computer, which serve as the external image processing unit (16), also perform the functions of the first sensor (14) and the second sensor (15). In this case, a transmission device is not required. The image processing unit or the external image processing unit (16) processes the obtained images and spectra via software, stores the acquired data and the outputs resulting from data processing in a memory, or transmits them to another device.

[0061] In one embodiment of the invention, transmittance-based measurements can also be performed either instead of or alongside reflectance measurements. For this purpose, the light sources are positioned on a detachable illumination unit that can be placed externally, as also shown in Figure 3.

[0062] The invention relates to systems enabling the examination of the optical and imaging properties of a defined region of space, namely the object (1), for use in forensic cases and marker analyses. An object (1) exhibits different optical characteristics under illumination with light of different wavelengths. When the image (4) emitted from the object (1) under such illumination is passed through appropriate optical filters (8), the two-dimensional luminescence, optical, and imaging properties of the object (1) can be determined. Similarly, when this image (4) is passed through a slit (7) and an optical grating, the spectrum of the object (1) is obtained. For this purpose, a spectrometer has been developed comprising both a first channel (12), which is capable of obtaining the spectrum, and a second channel (13), which is capable of performing two-dimensional image analysis, specifically designed for forensic applications and marker examinations.

[0063] The invention further discloses embodiments that are substantially similar, differing primarily in the positioning and geometric configuration of the optical elements. In all embodiments, the object (1) is illuminated by light sources of optionally different wavelengths, such as LEDs (2) of varying wavelengths. For transmission-based measurements, the sequence of LEDs (2) with different wavelengths is adjusted accordingly. Fundamentally, the invention provides for splitting the image (4) into two parts by means of an image duplicator (5), preferably a prism, thereby generating two channels. The images (4) obtained from these two channels are subsequently passed through optical components and captured by at least one camera of the external image processing unit (16), where the acquired data is processed by software and converted into meaningful information.

[0064] In an exemplary embodiment of the invention, a diaphragm (3) is employed to define the boundaries of the region under examination, thereby forming an optical aperture. The prism then splits the image (4) of the region defined by the diaphragm (3) into two parts. For spectroscopic analysis of the image formed on one surface of the prism, the image in the first channel (12) is first passed through a narrow slit (7). The slit (7) functions to diffract the photons originating from the examined region into their constituent wavelengths. Diffraction gratings are further employed to increase diffraction and expand the spectrum, thereby enhancing resolution and sensitivity. Optical filters (8) are utilized to selectively block certain portions of the spectrum and to render the spectral information more meaningful with respect to the property being analyzed. For image processing of the defined region, the second channel (13) is further provided with beam-collecting lenses (11).

[0065] The handheld spectrometer of the invention possesses the same capabilities as spectrometers used under laboratory conditions. Since the spectrometer is primarily intended for use with smartphones, it includes an application compatible with both Android and iOS operating systems. Moreover, the application is capable of using the smartphone’s cameras independently, allowing the first channel (12) and the second channel (13) measurements to be conducted independently of each other.

[0066] Cameras integrated in modem smartphones have advanced considerably in recent years. These high-resolution cameras, when combined with appropriate optical approaches, software, and measurement techniques, are capable of functioning as one-dimensional diode arrays within a spectrometer. In other words, a wavelength-resolved image captured by a smartphone camera can be analyzed by dedicated software executed on the smartphone, thereby providing functionality comparable to that of laboratory -grade spectrometers. For example, when the smartphone is utilized as the external image processing unit (16) and subjected to calibration, the spectrum obtained from the diffraction grating (optical grating) produces a two-dimensional (Cartesian) image on the smartphone camera. Each pixel of this image corresponds to a discrete “diode” in the spectrum. By employing multiple light sources with known wavelengths, such as lasers, to calibrate the entire spectral range, it becomes possible to precisely determine the exact wavelength associated with each pixel across the spectrum.

[0067] The spectroscopic measurements to be performed with the spectrometer of the present invention are detailed as follows.

[0068] Transmittance (T) Measurement: This process utilizes the first channel (12). White LEDs (2) or combinations of LEDs corresponding to white in different colors are used for illumination. The white light is first passed through a blank (air) to obtain a reference signal, and then through the sample (solid / liquid) to obtain a sample signal. The two signals are ratioed to generate the transmittance spectrum. Absorbance (A), which is the inverse of transmittance, is calculated using the formula (T=l / A). The determination of the absorption coefficient is carried out using the Beer-Lambert law.

[0069] Reflection Measurement: The first channel (12) is used. White LEDs (2) or LEDs of different wavelengths are employed to produce white light. A spectrum is first obtained from a reference surface, such as a mirror, and then from the sample. The two signals are ratioed to generate the reflection spectrum.

[0070] Luminescence spectrum measurement: In the first channel (12), LEDs (2) of different wavelengths, preferably UV, are used. The luminescence emission spectrum is measured using an appropriate optical filter, such as long-pass, band-pass, or notch-pass filters.

[0071] Color measurement: The color measurement is performed by calibrating the RGB values of the object (1) image obtained from the second channel (13) against a standard color space. In this process, LEDs (2) of different wavelengths are used to produce white light.

[0072] Cartesian luminescence measurement: This process uses the second channel (13). Especially in marker (tag) applications, the image (4) obtained from the object (1) is passed through multiple appropriate optical filters (8) to detect changes occurring in the image (4). For illumination, LEDs (2) of different wavelengths, which may also have different characteristics beyond wavelength, are used individually.

Claims

CLAIMS1. A spectrometer comprising a first channel (12) configured for spectroscopic measurements and a second channel (13) configured for image processing, characterized in that it comprises: a body comprising the first channel (12) and the second channel (13), light sources (2), selected from LEDs or lasers of different wavelengths, mounted on the body and directed toward a target object (1) through the body, said light sources being configured to illuminate the target object (1) by emitting radiation in the ultraviolet, visible, and infrared regions of the electromagnetic spectrum, an image duplicator (5) located inside the housing, which splits the light received from the object (1) into two beams and directs them to a first channel (12) and a second channel (13), a first image sensor (14) and a second image sensor (15) respectively located on the first channel (12) and the second channel (13), a slit (7) and an optical grating sequentially arranged on the first channel (12) in the optical path from the image duplicator (5) toward the first image sensor (14), a first optical filter (8) positioned on the first channel (12) between the slit (7) and the first image sensor (14), a second optical filter (8) positioned on the second channel (13) between the image duplicator (5) and the second image sensor (15).

2. A spectrometer according to claim 1, characterized in that the first channel (12) and the second channel (13) are aligned with the output directions of the image duplicator (5).

3. The spectrometer according to claim 1, wherein the second channel (13) is aligned with one output direction of the image duplicator (5), the first channel (12) intersects at an angle with the other output direction of the image duplicator (5), and at least one reflector is provided at said intersection point.

4. A spectrometer according to claim 3, characterized in that the reflector is an elliptical mirror (6).

5. The spectrometer according to claim 3, wherein the optical grating is a reflective diffraction grating (10) positioned at the intersection point and configured to function as the reflector6. The spectrometer according to claim 1, wherein the optical grating is a transmissive diffraction grating (9).

7. A spectrometer according to claim 1, characterized in that the image duplicator (5) is a prism.

8. The spectrometer according to claim 1, wherein the spectrometer further comprises a diaphragm (3) configured to transmit only the light originating from the targeted object (1).

9. A spectrometer according to claim 8, characterized in that said diaphragm (3) has an adjustable diaphragm.

10. The spectrometer according to claim 1, wherein the spectrometer comprises an image processing unit configured to process the data received from the image sensors.

11. The spectrometer according to claim 1, wherein the spectrometer comprises at least one transmission device configured to transmit the data obtained from the image sensors to an external image processing unit (16) configured to process said data.

12. A spectrometer according to claim 1, characterized in that, instead of the first sensor (14) and the second sensor (15), it comprises a mount accommodating two cameras belonging to an external image processing unit (16) having multiple cameras.

13. A spectrometer according to claim 1, characterized in that the light sources are LEDs (2) of different wavelengths.

14. A spectrometer according to claim 1, characterized in that the light sources are lasers of different wavelengths.

15. A spectrometer according to claim 1, characterized in that the light sources are on a detachable illumination unit that can be positioned externally for performing transmittance-based measurements.

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