FIELD OF THE INVENTION

The disclosed subject matter relates to the Counterfeit Currency Detection Technique, and more particularly but not exclusively, to Counterfeit Currency Detection device for Indian Rupees. The growing menace of fake and counterfeit currency is evident as newspaper reports of a huge cache of fake currency notes being seized appear every day. The advancements in the field of computers, photocopiers and scanners have made duplicating currency note very simple. The unsuspecting masses have no mechanism of differentiating the fake from the genuine. The disclosed subject manner tries to create a device which combines two methods to detect the fake currency and distinguish it from real ones.

BACKGROUND OF THE INVENTION

[001] The battle to prevent counterfeiting has become difficult with the development of sophisticated printing techniques, the counterfeit currencies have become on- par with the original currency.

[002] The disclosed device is an attempt to make a device easily and quickly identify fake notes by using two methods along with automation.

SUMMARY OF THE INVENTION

[003] In this method we use 2 methods to identify counterfeit currency One is using Ultra Violet (UV) detection using lab view; the other is using the polarization of light when passed through the currency.
[004] One of the earliest methods was to use UV detection. It is based on the principle of detection of special kinds of inks that are only visible under UV light. Since this process is slow, automation is introduced using (NI-IMAQ).

[005] The polarization is based on the principle that, the Indian currency is not made of paper, but is a blend of cotton, paper and linen. Moreover the tree bark from which the currency is made is called the Balsam fig, which also contains a large percentage of cellulose.

[006] Thus it is safe to say that Cellulose constitutes a considerable composition of the currency. Although the other ingredients will have some effect on the polarization angle, the polarization angle of the currency is almost close ^to that of cellulose, and the angle obtained by passing laser through the currency is unique thus it is made use of authentication of the original currency from the forged ones.

[007] Ultraviolet radiation itself is invisible to the human eye, but illuminating certain materials with UV radiation prompts the visible effects of fluorescence and phosphorescence. Black light testing is commonly used to authenticate antiques and banknotes. Two of the most critical anti-counterfeiting features of Indian currency are the paper and the ink. The exact composition of the paper is confidential, as is the formula for the ink. The ink and papa* combine to create a distinct texture, particularly as the currency is circulated. These characteristics can be hard to duplicate without the proper equipment and materials.

[008] The basic working principle is based on Fluorescence. Fluorescence is a luminescence that is mostly found as an optical phenomenon in cold bodies, in which the molecular absorption of a photon triggers the emission of another photon with a longer wavelength. The energy difference between the absorbed and emitted photons ends up as molecular vibrations or heat. Usually the absorbed photon is in the ultraviolet range, and the emitted light is in the visible range, but this depends on the absorbance curve and Stokes shift of the particular fluorophore.

[009] The term 'fluorescence' is described as the essence of the mineral fluorite, composed of calcium fluoride, which gave a visible emission when illuminated with "invisible radiation" (UV radiation). Thus when the UV light falls on the currency the printed ink, fluorescence is observed and the currency "glows".

[0010] The Indian currency is coated with special dyes that are visible only in UV light. With the advancements in technology, the counterfeit currency is coated with similar dyes that give positive results to UV test.

[0011] The existing device which performs the UV test is capable of testing only one currency at a time, and the process is not automatic, as well as it requires humans to check the genuineness of the currency, which are prone to human errors.

[0012] NI-IMAQ for USB Cameras driver software allows users to configure any DirectShow imaging device and acquire images into Lab VIEW. Devices that support this feature include USB cameras, webcams, microscopes, scanners, and many consumer-grade imaging products. Using NI-IMAQ this process can be automated using a computer.

[0013] The basic logic is developed using Image Acquisition-Laboratory Virtual Instrument Engineering Workbench (IMAQ-LABVIEW) (Figure 2). The images of the original currencies are fed to the computer at various angles, also images of various currencies at different ware & tear levels are also fed to the IMAQ database.

[0014] The currency is initially placed on the holder which is driven by the servo mechanism and illuminated by the UV source. This currency is captured using an HD camera and the images are sent to IMAQ-LABVIEW.

[0015] The current image is compared with the images of the original currencies from the database and if the currency is real the status glows green (Figure 3) else in red (Figure 4). The entire setup is show in figure 5. The accuracy of this method depends on the number of currency images captured and fed into the database. Another advantage is that bulk notes can be scanned and the counterfeit currencies can be identified.

[0016] Polarization is a property of waves that can oscillate with more than one orientation. Over each cycle of a sinusoidal wave, the electric field vector (as well as the magnetic field) traces out an ellipse.

[0017] The shape and orientation of this ellipse defines the polarization state. Some examples of the evolution of the electric field vector, with time, at a particular point in space, along with its x and y components at the base is the path traced by the vector in the transverse plane are shown.

[0018] The net result is polarization along a particular direction (depending on the relative amplitudes of the two components) in the x-y plane over each cycle. Since the vector traces out a single line in the plane, this special case is called linear polarization. Most polarizing filters produce linear polarization from unpolarized light. This change in polarization state is used in this method to identify the counterfeit currency.

[0019] Ellipsometry is an optical technique for investigating the dielectric properties of substances. The name "ellipsometry" stems from the fact that Elliptical polarization of light is used. The Ellipsometer is a device which can be used to find the refractive index of the currency when the thickness of the film is known

[0020] Ellipsometry can.be performed by both reflective and refractive setup. It measures the change of polarization upon reflection or transmission and compares it to a model. Typically, ellipsometry is done only in the reflection setup. The exact nature of the polarization change is determined by the sample's properties (thickness, complex refractive index or dielectric function tensor).

[0021] The Indian currency is not made of paper but is a blend of paper and cloth. The paper used for making the currency is made from the balsam fir tree. The currency contains 30-40% cotton. Cotton is the purest form of cellulose and is present as cellulose I in it. Cellulose I is crystalline at room temperature and becomes amorphous when heated to 340F.

[0022] When cotton is manipulated or subjected to various chemical processes in order to convert it into fiber, the cellulose I is converted to cellulose II or III or IV, which are also crystalline. Thus by measuring the polarization properties of cellulose I, II, III and IV, we can extend it to the property to the currency. The thickness of the currency was found to be l00microns with an error of ±5.

[0023] Spin coating is a procedure used to deposit uniform thin films to flat substrates. Usually a small amount of coating material is applied on the center of the substrate, which is either spinning at low speed or not spinning at all. The substrate is then rotated at high speed in order to spread the coating material by centrifugal force. A machine used for spin coating is called a spin coater, or simply spinner.

[0024] Rotation is continued while the fluid spins off the edges of the substrate, until the desired thickness of the film is achieved. The applied solvent is usually volatile, and simultaneously evaporates. So, the higher the angular speed of spinning, the thinner the film. The thickness of the film also depends on the viscosity and concentration of the solution and the solvent. The following steps are performed in identifying the refractive index of the currency 1) Preparing the sample 2) Spin coating the sample on Silicon wafer 3) Ellipsometric analysis

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]* Embodiments are illustrated by way of example and not limitation in the Figures of the accompanying drawings, in which like references indicate similar elements and in which:

[0026] FIGURE. 1 illustrates a schematic layout of a of the device, in accordance with an embodiment;

[0027] FIGURE. 2 illustrates the physical device which is embedded with both methods of testing, in accordance with an embodiment; and [0028] FIGURE. 3 illustrates the output of the device which shows GREEN for orginal currency and RED for fake currency, in accordance with an embodiment;

DETAILED DESCRIPTION OF EXPERIMENT

[0029] In order to prepare the currency sample, the currency is mixed with lithium chloride and dimethyl acetamide and heated to 70°C in the presence of nitrogen gas. The sample is heated for about 40 minutes with constant stirring and It is found that the cellulose disintegrates leaving behind the currency in the form of a pulp. The pulp can be coated on any substrate and used for analysis.

[0030] Once the pulp is prepared, it can be coated on a substrate. Here the silicon wafer is used. This is because, since the ellipsometer works on reflective setup, the silicon wafer will provide more accuracy. The wafer is cut in 2x2 or 4x4cm and is placed in the spin coating device. The pulp is placed on the wafer and the device is sealed using the lid. The wafer along with the pulp is rotated at 2000 RPM for 5 minutes. Finally we get a sample with a thickness of about l00microns.

[0031] The sample which is coated on the silicon wafer is placed in the viewing area of the ellipsometer. The ellipsometer has 2 arms, one contains the source and the other contains uie detector. The ellipsometer is interfaced with a computer and has dedicated software, where the necessary details are fed.

[0032] The ellipsometer works on the principle of differential reflection. It measures the phase difference of the light reflecting from the surface of the sample and the surface of the substrate. This phase difference along with the thickness of the coat can be used to determine the refractive index of the currency. From the refractive index the Brewster's angle can be calculated using the formula.

[0033] The block diagram for polarization is shown. It consists of a laser. Here a HE-Ne laser is used. A 5-10mW LASER is used because, the laser should be powerful enough to penetrate the currency, but not too powerful that it burns the currency.

[0034] The holder section is common to both the polarization and UV-IMAQ detection technique. The holder section is where the currency is fed. It consists of 2 servo motors which are driven by the micro controller.

[0035] The half wave plate is a device is an optical device that alters the polarization state of a light wave travelling through it. It generally alters the polarization state of linearly polarized light. Thus the light which is coming out of the currency can be regulated using the wave plate. The wave plate is of 5mm in diameter.

[0036] Finally the analyzer which is another polarizer is attached to the light detector and a computer. When the holder is inclined to the Brewster's angle, maximum intensity of light is incident at the detector and hence, the output is high. Thus this can be used to determine the accuracy of the currency.

[0037] The sources include He-Ne laser, UV source (UV-visible LEDs) which are used for polarization test, UV detection respectively. These sources have been selected based on the test performed prior to the purchase

[0038] The basic purpose of the servomechanism circuit is to determine the Brewster's angle. By adjusting the pot the angle with which the servo motor turns varies. Thus the currency holder rotates and the angle at which the polarization of light occurs can be found. This gives the Brewster's angle.

[0039] The detectors include a High response photo transistor mounted with amplifier, UV detector and, for performing the 2 analysis respectively. The above mentioned detectors are chosen because of their high response time, which is found out through experiments prior to the purchase.

[0040] The holder section is common to both the polarization and the UV detection method. The UV detection has a High definition camera on top of the holder section. When the currency is in place. The HD camera captures the image of the currency under the UV light and feeds it to the NI-IMAQ.

[0041] The logic defined in the IMAQ, will compare the image obtained with that of the images in the data base and the result is displayed in the indicator. If a mismatch is identified, the RED LED will glow as shown as in the figure. Where as if the currency is identified as original, then the GREEN LED will glow.

CLAIMS

We claim,

1. The Counterfeit Currency Detection system comprising of three parts which are vital for
device to detect the fake notes:

a. A Image Processing

b. A Polarization Principle and

2. The Counterfeit Currency Detection system, discloses a device which can be used to detect fake or Counterfeit Indian Rupee notes in quicker manner.

3. The Counterfeit Currency Detection system according to claim 1, further comprises of the NI-IMAQ system by using Lab-View the various images of original currency are uploaded and are compared with the note to be tested.

4. The Counterfeit Currency Detection system according to claim 1, further comprises of the mechanism by using polarization technique to further check whether the currency is genuine.

5. The Counterfeit Currency Detection system according to claim 1, further comprises of Holographic Technique which can be incorporated in the system.