REGULA 7708 User manual
Certied Quality
Management System
MAGNETO-OPTICAL HYSTERESIGRAPH
MOHYSTER REGULA 7708
Operating Manual
CONTENTS
1 INTENDED USE 4
2 APPLICATION AREAS 5
3 DESIGN AND OPERATION 6
4 SCOPE OF DELIVERY 8
5 OPERATION 9
51 Setting-up 9
52 Software installation 10
53 Object setting and positioning 10
54 Description of the "MOHyster control" functional toolbar of the CADR software 11
55 Performance of magnetic measurements 14
551 Parameters of the "Magnetic measurements" function 15
552 Using the "Magnetic measurements" function 16
553 Magnetic induction topogram processing and analysis 18
554 Magnetic induction histogram processing and analysis 23
56 Construction of magnetic hysteresis characteristics 29
561 Brief explanation of the magnetic hysteresis phenomenon 29
562 Parameters of the "Hysteresis" function 31
563 Using the "Hysteresis" function 32
564 "Hysteresis" function windows elements and navigation 34
565 Selecting the hysteresis characteristic type (В-Н, Ф-Н or М-Н) 35
566 Processing and analysis of magnetic hysteresis characteristics 36
57 Construction of a magnetic eld tomogram 42
571 Parameters of the "Magnetic tomography" function 42
572 Using the "Magnetic tomography" function 43
573 Processing and analysis of magnetic tomograms 45
6 TEST OBJECTS AND COMPLEX PERFORMANCE MONITORING 47
61 Test objects 47
62 Estimating the spatial resolution using test object No 1 48
63 Estimating the measurement noise using test object No 2 49
64 Estimating the measurement accuracy using test object No 3 50
7 SHUTTING DOWN 52
8 ROUTINE MAINTENANCE 52
9 SPECIFICATIONS 53
10 TRANSPORTATION AND STORAGE 54
11 DISPOSAL 57
12 MANUFACTURER’S WARRANTY 57
13 CERTIFICATE OF CONFORMITY 58
4
1INTENDED USE
This operating manual (hereinafter referred to as the Manual) describes the design,
operating principle and service instructions for the hardware and software system
of magneto-optical hysteresigraph MOHyster Regula 7708 (hereinafter referred to as
the device, MOHyster and the MO hysteresigraph)
MOHyster is designed for instrumental examination of magnetic printing and magnetic
security features of documents by means of determination of multiple magnetic
characteristics of these objects, such as:
1) function of 2D spatial distribution of the stray magnetic eld on the object surface
В(x, y), which can be represented as:
11 topogram (spatial distribution function) of the magnetic induction normal
component B(x, y) in the form of an accumulated (measuring) magneto-optical
image (Fig 1-1), where the brightness of the points represents the value of В for
each of the image points;
12 histogram (probability density function) of the magnetic induction normal
component В in the form of a graph (Fig 1-2) which shows the number of points
of the magneto-optical image in the columns These points have the corresponding
value of the stray magnetic eld normal component В [T];
13 modulus of the magnetic ux normal component Φ [Wb] through the magneto-
optical sensor area (Fig 1-2), calculated based on the estimation data of magnetic
induction В(x, y);
2) static magnetic hysteresis characteristics of different types: by magnetic ux Ф-Н
(Fig 1-4), by magnetic induction В-Н, and by magnetization М-Н;
3) function of 3D spatial distribution of the stray magnetic eld over the object surface
В(x, y, z), which can be represented as:
31 tomogram (layer structure) of the stray magnetic eld, consisting of a set
of 2D functions В(x, y), measured at different distances z from the object surface;
32 graphs of magnetic induction maximum functions Вm(x, y, z) or magnetic
ux Ф(z);
33 volume integral of the magnetic induction ∫В(x, y, z) [T*m3]
The device comes with specialized software designed to perform the following:
operation mode selection, conguration and control;
document authenticity verication/identication by comparative examination
of magnetic characteristics using reference specimens;
secondary mathematical processing of magneto-optical images with the purpose
of their analysis, comparison, geometry estimation and intelligibility/visibility
enhancement;
documentation of ndings and adding data with magnetic parameters
of document security features to the databases of security documents
To illustrate the technical capabilities of the device, below is a screenshot (Fig 1)
of the main window of specialized software CADR (with the MOHyster module), showing
the results of the examination of a magnetic security feature of a banknote A $100
banknote of the 2006 series was used as an example 1 – display area of the accumulated
magneto-optical images; 2 – display area of the magnetic induction Вn histograms and
the magnetic ux Фn calculated values; 3 – display area of the 3D magnetic history
of measurements of the current hysteresis curve; 4 – display area of the magnetic
hysteresis characteristics
5
Figure 1
APPLICATION AREAS
Possible application areas of the MO hysteresigraph:
applied scientic research in the eld of developing new and improving existing
magnetic security features of documents;
judicial forensics: authenticity verication of securities and banknotes;
classication of methods of counterfeiting of magnetic protection of securities
and banknotes Classication and identication research of magnetic printing;
production of securities, banknotes, forms: quality control of magnetic security
features; research of magnetic printing technologies and materials;
banking: authenticity verication of securities and banknotes;
border and customs authenticity verication of secured documents and
banknotes
2
6
DESIGN AND OPERATION
General view of MOHyster (Fig 2–3):
(A) – case;
(B) – object table;
(C) – magneto-optical visualization and magnetic measurement device;
(H) – pressing unit;
(D) – magnetic units of the controlled object magnetization device;
(E) – light target for object positioning;
(F) – preliminary object magnetization/demagnetization device;
(G) – control and indication elements;
(I) – connectors;
(1) – spring arms;
(2) – power button;
(3) – power indicator;
(4) – digital display;
control buttons:
(5) – move the object table to the object setting/removal position;
(6) – move the object table to the magneto-optical visualization position;
(7) – manual object position adjustment;
(8) – magnetization intensity setting;
LED indicators:
(9) – green – operation in progress;
(10) – red – self-test error;
connectors:
(11) – power supply unit connector;
(12) – computer connector (USB);
(13) – adjustable feet
MOHyster consists of the following main parts (Fig 2): case (A) with a at work
surface along which the object table (B) moves forward and backward Spring arms (1)
are used for xing the object on the object table In the middle of the protruding upper
part of the case, there are magneto-optical visualization and magnetic measurement
devices (C), which are magneto-optical sensor and inductors (sources of controlled
compensation magnetic eld Below the magneto-optical visualization device there is
a pressing unit (H) for uniform pressing of the object to the surface of the magneto-
optical sensor and its removal On the sides of the magneto-optical visualization device
there are symmetrical magnetic units of the controlled object magnetization device (D)
In the middle of the at work surface of the case there is a light target for object
positioning (E) and a preliminary object magnetization/demagnetization device (F)
On the front panel of the device base there are control and indication elements (G):
power button (2), power indicator (3), digital display (4) and mode control buttons
Control buttons: "move the object table to the object setting/removal position" (5), "move
the object table to the magneto-optical visualization position" (6), "manual object position
adjustment" (7) and "magnetization intensity setting" (8) On the same panel there are
LED indicators: green – "operation in progress" (9) and red – "self-test error" (10)
On the back panel of the device base (Fig 3) there are connectors (I): a connector
for power supply unit (11) and a USB connector for connecting to a computer (12)
On the bottom surface of the base there are four adjustable feet (13) with plastic pads
for protection of the surface on which the device is installed
3
7
Figure 2
Figure 3
8
The MO hysteresigraph visualizes stray magnetic elds of magnetic security features
made with magnetic inks, threads, bers and other magnetic materials using a magneto-
optical sensor (a sensitive element of the magneto-optical visualization and magnetic
measurement device (C) based on the magneto-optical Faraday effect Digitized
magneto-optical images are transferred to a computer for processing and saving in any
bitmap format
When performing magnetic measurements, the magneto-optical sensor, which
detects both the object’s stray magnetic eld and the compensation magnetic eld
generated by the inductor, determines the state of balance of these elds in each point of
the visualization area Thus, the combined digital processing of a set of magneto-optical
images (128 magneto-optical frames with a size of 928×1184) obtained under calibrated
compensation magnetic eld (64 levels from 0 to +112mT and 64 levels from 0 to
-112mT), allows producing an accumulated magneto-optical image, where the brightness
of each point corresponds to the value of Bn
The stray magnetic eld of an object is determined by the following:
1) remanent magnetization, which can be set (from 0 to the maximum) by preliminary
demagnetization or magnetization (+120 kA/m or -120 kA/m) in the preliminary magne-
tization/demagnetization device (F);
2) excitation magnetic eld intensity, which is controlled by the controlled magnetization
device (D) in the range of 0 to 100 kA/m with a sampling rate of 5 kA/m
The object to be analyzed is xed on the object table (B), which can move between
the said magnetization devices Depending on the selected magnetic measurement
conditions, the object can be premagnetized in a specied direction or demagnetized using
the preliminary magnetization/demagnetization device (F) The intensity of the applied
magnetic eld, acting at the time of the measurement, can also be selected by setting
the required value for the controlled magnetization device (D)
MOHyster has an internal microprocessor which is controlled by specialized PC software
through the USB Most of time-consuming measurement cycles (such as obtaining
hysteresis characteristics) are automatic
SCOPE OF DELIVERY
The device comes standard with the following:
Magneto-optical hysteresigraph MOHyster Regula 7708
Power supply unit
Personal computer (optional)
Specialized software CADR (memory card with the MOHyster module)
Driver for the MO hysteresigraph
USB cable
Accessory for transportation
External magnetization unit HiCo (optional)
Operating Manual
Cover
Spare uoroplastic covers of the pressure unit (SPTA)
Spacer kit, 30–1200 µm
Test object set
Conguration les (TO_1gif; TO_2moh; TO_3moh)
PC and power supply unit specications are provided in Section 9 Instructions for
the accessory for transportation are provided in Section 10
4
9
5.1
OPERATION
ATTENTION!
This equipment is not suitable for use in locations where children are likely to
be present
WARNING!
Keep body parts away from moving parts DO NOT put your hands or
ngers near the moving parts (the moving portal) Make sure machinery,
equipment and power tools are completely off before you try replacing,
cleaning or repairing parts
Setting-up
The place for installing the MO hysteresigraph must be selected based on magnetic
measurements, outside the ranges of any electromagnetic sources, such as power and
welding transformers, power cables, contactors or high-power electrical machinery
The device should be positioned so that the power plug and the power connector on
the device body are easily accessible
Before turning the device on for the rst time:
check for any visible defects or damage If there are any defects or damage,
please contact the supplier;
dismantle and remove the transportation kit Unscrew the nuts (6) and
remove the jumpers (4) and thrust plates (2) (Fig 46–48) Keep the parts
of the transportation kit for the entire service life of the device
Place the device on a at level surface of an ofce or laboratory desk Adjust the feet (13)
(Fig 3) until the device is stable on the surface
WARNING: HEAVY OBJECT!
The device is very heavy To reduce the risk of lifting related injuries, death,
or damage to your device, we recommend that a minimum of two people lift
the device It is important to use proper lifting posture when lifting and/or
moving the device
Warning! Remove all objects and documents from the desk. In particular, ensure that
there are no small objects of ferromagnetic materials (paper clips, screwdrivers, screws,
nuts, washers, scissors, rulers, etc.), since they can be attracted by powerful magnets
of the device or trapped inside the device by its moving parts. If a ferromagnetic object
gets inside the device, the magnetization system may be damaged or disadjusted.
Connect the power supply unit to the connector (11) (Fig 3)
Connect the USB cable supplied with the device to the connector (12) (Fig 3) Connect
the other end of the cable to the appropriate USB port of your PC
Plug the power supply cable in a 110–220 V outlet The power indicator (3) (Fig 2)
on the front panel should light up, indicating that there is a 24 V DC input
Press the power button (2) (Fig 2) The device will perform a self-test procedure, dur-
ing which you can see a series of movements of the object table (B), controlled object
magnetization device (D) units, magneto-optical visualization and magnetic measurement
device (C) and pressing unit (H) The self-test procedure takes a few seconds Then
the device stops, and if the self-test was successful, the digital display (4) shows "ready";
if the self-test was failed, the display shows the error code ("XXX_error")
If there are systematic self-test errors, please contact the supplier
5
10
Software installation
MOHyster is supplied with the following software:
1) Specialized software CADR (with the MOHyster module) for device control, data
processing, analysis and storage;
2) Device driver
Software installation procedure:
Insert the external media (CD or ash memory card) with the MOHyster software
into your computer The software can also be downloaded from wwwladorgua Create
a working directory and copy the software into it
Turn on the device as described in s 51 and wait for the self-test to complete
The operating system will detect a new USB device and launch the Device
Driver Installation Wizard automatically During the installation, specify the path to
the device driver
When the installation is complete, open the Device Manager and check that there is
a device named "Magneto-Optical Hysteresigraph" in the "ForensicDevices" section Ensure
that the device is installed correctly (without "?" or "!" marks in the Device Manager)
After the driver is installed, the CADR software is ready to use The CADREXE le can
be launched either directly from the working directory or from a shortcut in any place
convenient for you
Since all the described below operations with the device use the CADR software,
the program must be running during the entire session It is also necessary to open
the "MOHyster control" toolbar to connect the device to the software (see s 54)
CAUTION!
A strong electrostatic discharge applied to the device body may cause its
malfunction In this case, it is recommended to turn the device off and on again
and restart the CADR program
Object setting and positioning
After the device is turned on with the power button (3) (Fig 2) and the self-test
is completed, the object table moves to the specic position ("object setting/removal
position" (Fig 4) When in this position, the central rectangular positioning window (1)
of the object table (2) is located above the light target, which is four bright red-orange
light spots that indicate the angular vertices of the rectangular contour of the magneto-
optical visualization area
If the object table is in a different position (which is possible during operation), move
it to the object setting/removal position by pressing the button (3) on the front panel
Then release the spring arms (4), slightly lift the top (5) of the object table
(approx 1–2 mm up) by hand and place the document in the formed slot Holding
the object table top (5), slide the document inside the table with your ngers (through
the windows (6)) and position the object so that the visualization area is within
the positioning light target (2) Lower the object table top (5) and leave the spring arm
stops (4) in the free position, since the positioning of the object is not yet complete
Press the button (7) on the front panel to move the object table to the magneto-optical
visualization area A window displaying the magneto-optical image of the object in real
time will automatically open the CADR software
If the magneto-optical image lacks contrast, the magnetization of the object may
be insufcient In this case, press the button (9) on the front panel of the device
The controlled magnetization system will generate a magnetizing eld of 50 kA/m Pressing
the button (9) again will set the magnetizing eld intensity to 0 kA/m This can be useful for
5.3
5.2
11
Figure 4
an initial rough estimation of the type of magnetic material of the object (if the material is
magnetically soft and does not leave remanent magnetization, the magneto-optical image
of the object will disappear) To adjust the position of the object, set the magnetizing
eld intensity to 50 kA/m by pressing the button (9) (the intensity value is indicated on
the digital display (4) (Fig 2))
If the object needs to be slightly moved or rotated relative to the magneto-optical vi-
sualization area, activate the object position adjustment mode by pressing the button (8)
The pressing unit will be operating in the cyclic mode: for a certain period of the time
cycle the object is pressed to the surface of the magneto-optical sensor (object cannot
be moved), then the object is released from the surface of the magneto-optical sensor
(object can be moved)
Move the object with your ngers through the windows (6) while holding the object
table top (5) up Note that in order to reduce distortion and noise during the positioning
an object, the visible magneto-optical image area (1024×1280 pixels in the measurement
mode) will be reduced to 928×1184 pixels by cutting off the image edges
When the positioning of the object is complete, x the position by pressing the spring
arm stops (4)
All the object setting and positioning operations described above can be performed
using the CADR software tools (see s 54)
Description of the "MOHyster control"
functional toolbar of the CADR software
The "MOHyster control" function toolbar (Fig 6) is used for controlling MO hysteresi-
graph MOHyster and estimating magnetic characteristics of objects
Launch the CADR software by double-clicking a shortcut or by double clicking
the CADREXE le in the installation directory
In the opened program window (Fig 5), click the (A) "MOHyster control" button, which
is located in the upper left corner of the toolbar
5.4
12
The "MOHyster control" functional toolbar will be displayed (Fig 6)
On the "MOHyster control" toolbar there are function buttons for controlling the device
Some functions allow parameter setting To open the settings menu, right-click one
of the following buttons:
– enable pressing unit cyclic mode: for a certain period of the time cycle the object
is pressed to the surface of the magneto-optical sensor (object cannot be moved),
then the object is released from the surface of the magneto-optical sensor (object can
be moved) This operation is used to adjust the position of the object The following
parameters can be congured;
– output a single frame of the magneto-optical image of the document in high
quality mode (1024×1280 pixels) Multiple initial magneto-optical images obtained with
various magnetic eld parameters of the inductor are used to create this accumulated
high-quality frame The following parameters can be congured;
– perform magnetic measurements (determining the spatial distribution function
value of the stray magnetic eld on the object surface), with the output in the form
of: a topogram (accumulated magneto-optical image of 928×1184 pixels), magnetic
induction histogram and the magnetic ux modulus value Parameters can be congured
For a detailed description, see s 55;
– construct a magnetic eld tomogram by performing magnetic measurements at
various distances from the object surface Parameters can be congured For a detailed
description, see s 57;
Figure 6
Figure 5
13
, and – construct individual hysteresis curves: 1 – initial magnetization
branch; 2 – magnetic return branch; 3 – magnetization reversal branch Parameters can
be congured For a detailed description, see s 56;
– construct full hysteresis characteristic, consisting of the 3 above hysteresis
curves Parameters can be congured For a detailed description, see s 56;
– lift the magneto-optical sensor one time This operation is used for service
purposes, such as drive adjustment;
– move the object table to the object setting/removal position;
– capture background magneto-optical images These are reference magneto-
optical images obtained with specied magnetic parameters without an object Such
images are used by automatic magneto-optical data processing algorithms to reduce
distortion and noise The following parameters can be congured;
, and – demagnetize or magnetize the object by a magnetic eld with an intensity
of +120 kA/m (the magnetization direction corresponds to the magnetic eld direction of
the controlled object magnetization device), or -120 kA/m (the magnetization direction
is opposite to the magnetic eld direction of the controlled object magnetization device);
– enable/disable the "Draft" mode for fast measurements, with a reduced number
of measurement iterations and generation of missing data by approximation The following
parameters can be congured;
– panel for adjusting the magnetic eld intensity
of the controlled object magnetization device The range of magnetic eld intensity adjustment
is 0 to 100 kA/m, with a sampling rate of 5 kA/m The intensity is controlled by setting
movable magnet units in the specied xed position On this gure the magnetizing eld
intensity is set to 50 kA/m
Setting and positioning operations can be performed using the CADR software tools
described above by pressing the corresponding menu buttons (Fig 5–6)
The button is used to move the object table to the object setting/removal position; Image
capture commands (buttons (В) and (С), Fig 5) are used for viewing the object: – one-time
capture (photo) or – continuous capture (video) When pressed, a window with the magneto-
optical image of 1024×1280 pixels will open in the main window of the CADR software (Fig 7)
Depending on the size of the monitor, the image may need to be scaled This can be done
with the following buttons on the toolbar: zoom in , zoom out , undo zoom and
the buttons (D), (E), (F) (Fig 5) The magneto-optical image in Fig 7 is displayed
zoomed-in
For better contrast of the viewed object, it is recommended to set the magnetizing eld
intensity to 50 kA/m
If the object needs to be slightly moved or rotated relative to the magneto-optical
visualization area, use the button to enable the position adjustment mode When
pressed, the pressing unit will operate in the pulsed mode: the object can be moved
relative to the image area of the magneto-optical sensor during the release phase
14
Performance of magnetic measurements
The "Magnetic measurements" function of the CADR software (Fig 6) sets
the hysteresigraph control algorithm, which allows determining the values of the 2D
spatial distribution function value of the stray magnetic eld on the object surface and
output the results in the form of a topogram B(x, y) (accumulated magneto-optical image
with a size of 928×1184 pixels), magnetic induction histogram Bn [mT] and the calculated
value of the magnetic ux modulus Ф [nWb]
The magnetic induction B in each point of the magneto-optical visualization area is
estimated by a compensation scheme using calibrated compensating magnetic eld
source (inductor) When performing magnetic measurements, the magneto-optical sensor,
which detects both the object’s stray magnetic eld and the compensation magnetic eld
generated by the inductor, determines the state of balance of these elds in each point of
the visualization area Thus, the combined digital processing of a set of magneto-optical
images (128 magneto-optical frames with a size of 928×1184 pixels) obtained under
calibrated compensation magnetic eld (64 levels from 0 to +112 mT and 64 levels
from 0 to -112 mT), allows producing an accumulated magneto-optical image, where
the brightness of each point corresponds to the estimated value of B(x, y)
5.5
Figure 7
15
The process of measurement can be speed up by enabling the "Draft" mode using
the button In this mode, only 32 magneto-optical measurement frames obtained
by application of 16 levels of calibrated compensation magnetic eld will be used, and
the missing data will be generated by approximation
The initial data for constructing a histogram of the normal component of magnetic in-
duction B generated by the "Magnetic measurements" function are the experimentally esti-
mated values of Bn(x, y) corresponding to the brightness distribution of the accumulated
magneto-optical image Stray magnetic eld induction is estimated in the range from
the magneto-optical sensor detection threshold (≈ 005 mT) to the maximum inductor
compensation eld (±112 mT) with a sampling rate of 0175 mT
Magnetic ux Ф is calculated in the CADR software by the histogram B and the known
area of the visualized image
5.5.1 Parameters of the "Magnetic measurements" function
To access the "Magnetic measurements" function parameters, rst open the "MOHyster
control" toolbar by clicking the button – (А) (Fig 5) On the "MOHyster control"
toolbar, right-click the button When clicked, the "Magnetic measurements" function
parameters window will open (Fig 8) with the recommended settings indicated
If the "Precise graph scales" checkbox is selected, the resolution of the point quantity
scale of the histogram lg(N) is increased to two decimal places, and the magnetic induction
scale B [mT] has the smallest scale spacing possible at the current graph window size
If the "001 % cutoff for calculating
the induction function maximum"
checkbox is selected and the threshold
value is selected, two vertical segments
indicating the values of B for the positive
and negative magnetic induction
distribution maxima are displayed in
the histogram eld of the magnetic
induction B This parameter is important
for the construction of the hysteresis
characteristics B-H and M-H (see s 56)
All of the above parameters of
the "Magnetic measurements" function do
not affect the measurement conditions, but
only change the format or interpretation
of the displayed data, therefore they can
Figure 8
be changed at any time, and they will be applied to all displayed measurement results (both
existing and new)
If the "Accumulation at low inductor currents" checkbox is selected, the measurement
algorithm changes, increasing the number of magneto-optical frames and accumulating
them at low inductor currents This reduces magneto-optical sensor noises, but increases
the duration of the measurement process
If the "Preliminary background image capture" checkbox is selected, the background
magneto-optical image will be automatically captured before the measurement begins
If this checkbox is not selected before performing magnetic measurements, there are two
scenarios: the program will use the previously captured background image if it is relevant,
or ask for a new background image if it is not irrelevant
16
Figure 9 To estimate the magnetic parameters of
a specied area, it is necessary to set and
position the object rst in accordance with
the recommendations described in ss 53–54
Start the "Magnetic measurements"
function To do this, left-click the "Magnetic
measurements" button (Fig 6) The progress
of the operation will be displayed on the digital
display (4) on the front panel of the device
(Fig 2)
Two new windows – "Accumulated Image"
(Fig 9) and "Magnetic Induction Histogram"
(Fig 10) will open in the CADR software window
The "Accumulated Image"window (Fig 9)
displays the iterative process of processing and
accumulating magneto-optical images obtained
by calibrated compensation magnetic eld
When the process is complete, a magneto-
optical image with a size of 928×1184 pixels*
is created and displayed directly in this window
* – to reduce distortion and noise, the visible magneto-optical image area (1024×1280 pixels
in the measurement mode, Fig 7) will be reduced to 928×1184 pixels (Fig 9) by cutting off
the image edges (peripheral points are not seen)
5.5.2 Using the "Magnetic measurements" function
The brightness of the image points corresponds to the estimated value of B(x, y) This is
the spatial distribution topogram of magnetic induction B(x, y), which can be further
processed and analyzed (see ss 623)
The "Magnetic Induction Histogram" window (Fig 10) displays the histogram
of the magnetic induction B, constructed based on the accumulated data displayed
in the "Accumulated Image" window Histogram B is a graphical representation of
the probability density function for the matrix of values B(x, y) The horizontal axis
shows the values of magnetic induction in the measurement range of ±112 mT (0 is
the central value) with a sampling rate of 0175 mT The vertical axis shows the number
of points N (in the logarithmic scale lg(N)) of the accumulated magneto-optical
image with the corresponding magnetic induction This window also shows the value
of the magnetic ux modulus Ф [nWb], which is calculated by integration of the function
B(x, y) over the area
Fig 10 shows the following: (1) – image points scale; (2) – magnetic induction scale;
(3) – histogram B of the analyzed object, (4) – values of the magnetizing eld Hexc, kA/m,
(5) – values of the magnetic ux Φ, nWb
When the "Magnetic measurements" function is performed again, a new "Accumulated
Image" window will open, and a new graph of histogram B will be constructed in the current
"Magnetic Induction Histogram" window Up to three histograms B can be constructed
in a single window
If there are two or more graphs in the same window, the distance d between the his-
tograms is calculated The distance d between histograms is dened as the sum of
the weighted modules of column differences for the compared histograms B Similarity
criterion: the lower the value of d, the more similar the histograms are and the higher
the probability that the two compared documents were printed using the same ink and
technology
17
The value of distance d, which characterizes the maximum deviation for genuine spe-
cimens, may be different for each type of document or banknote This value should be
established by trial in the process of experimental data accumulation
Figure 10
ATTENTION!
To save the results of magnetic measurements, make the "Accumulated
Image" window active (Fig 9), click the "Save" button on the CADR toolbar,
select the le format in the opened menu (GIF format is recommended,
BMP and PCX formats are allowed, JPG format is not recommended due to
the distortion of measurement data), and specify the le name and path for
saving If you close CADR, all unsaved data will be lost
ATTENTION!
Measurement of the magnetic parameters of objects can be performed under
various magnetization conditions, which is important for the classication
of magnetically hard and magnetically soft materials The examples shown
in Fig 7–9 were made with a magnetizing eld of 50 kA/m, which corresponds
to the unied value used in various magneto-optical measuring devices, such
as Regula 4197M MagMouse and Regula 7701M MagReader as well as magnetic
measurement specimens from the Currency database
To change the magnetizing eld intensity, use the "Excitation magnetization" slider
on the "MOHyster control" toolbar (Fig 6)
To prevent the effect of the remanent magnetization of the object on the magnetic
measurement results when measuring in applied magnetization eld with the magnetizing
eld intensity Н
ехс ≠ 0 kA/m, it is recommended to demagnetize the object using
the button on the "MOHyster control" toolbar (Fig 6) before beginning
the measurements
To achieve the maximum possible remanent magnetization of the object when
measuring by remanent magnetization with the magnetizing eld intensity Нехс = 0 kA/m,
it is recommended to magnetize the object using the button on the "MOHyster
control" toolbar (Fig 6) before beginning the measurements In this case, as a result
of measurements, the specimen printed with a magnetically hard material will have
18
a value of the remanent magnetic ux Φ > 0 nWb, and the specimen printed with
a magnetically soft material will have value Φn ≈ 0 nWb (specically, measurement noise
level of ≈ 0–02 nWb)
5.5.3 Magnetic induction topogram processing and analysis
Let’s consider the most general approaches to the processing of magnetic measure-
ment results through the example of comparative examinations of two specimens of
a 1 USD banknote: genuine and counterfeit (printed on a laser printer)
The compared banknotes were set and positioned in accordance with ss 53–54, with
examination areas in approximately the same position Measurements were performed
in accordance with ss 552 The measurement results were saved in four GIF les: two
les are the measurements in applied magnetization eld Нехс = 50 kA/m for the genuine
and counterfeit banknotes; the other two les are the measurements by the remanent
magnetization, with zero magnetization eld Нехс = 0 kA/m for the genuine and counterfeit
banknotes
The topogram of the accumulated magneto-optical image allows examining the spatial
distribution function of the magnetic induction normal component B(x, y) of the object
Analysis of the results of the measurements in applied magnetization eld Нехс = 50 kA/m
(Fig 11) To load a saved le (including the results of magnetic measurements), click
the "Open" button on the toolbar (C) of the CADR software, select the le name in
the menu and specify the path to its location The le will be opened in the current image
window of CADR (window (A) shown in Fig 11 there is an accumulated magneto-optical
image of the counterfeit banknote obtained in applied magnetization eld Нехс = 50kA/m)
If the "Open" command is selected while holding down the Shift key, the le will be opened
in a new window (in window (B) shown in Fig 11 there is an accumulated magneto-
optical image of the genuine banknote)
Figure 11
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Magneto-optical images in windows (A) and (B) have a scale of 1:1 (without zoom),
so only a part (approx 1/4) of each image is visible For ease of comparing images
in windows, arrange them horizontally, by pressing the "Tile" button on the CADR
toolbar (D)
If you visually compare magneto-optical images in windows (A) and (B), some differ-
ences can be observed in the print stroke width and contrast However, now we are
interested not in the brightness but in the magnetic characteristics of the image points,
ie in the spatial distribution topogram of magnetic induction B(x, y)
Various tools can be used to examine the topogram of magnetic induction B(x, y)
For example, you can use the "Magnetic Induction at Point" button on the CADR
toolbar (C) (Fig 12) When pressed, the navigation panel (D) is shown, where
the magnied magneto-optical image area around the point is displayed, with coordinates
x, y and magnetic induction value of this point displayed in the details You can select
the current point by clicking on any point of the magneto-optical image or on the graphical
window area of the navigation toolbar (D) If you select the current point while holding
down the Shift key, all points of the same (or nearby – based on the settings) level
of magnetic induction will be highlighted in color on the accumulated magneto-optical
image In addition, the number of points in the selected range B of the accumulated
magneto-optical image will be displayed in the status bar (E)
Figure 12
20
Figure 13
Points of the accumulated magneto-optical image with the set level of magnetic in-
duction B can also be selected using other tools, for example, by selecting the "Magnetic
Induction at Point" function on the parameter settings panel To do this, right-click
the button
A common magnetic induction value of ±1575 mT (red for +1575 mT and blue
for -1575mT) is set for the compared accumulated magneto-optical images (Fig 12)
The set magnetic induction value of ±1575 mT is not xed and can be set by the user
to achieve the best visualization and interpretability of the obtained comparison results
The comparison of the color contours (lines of equal magnetic induction) shows that
the genuine banknote (B) has larger (high energy) contours of lines with equal magnetic
induction, and they adjoin each other in the middle of magnetic ink strokes Such magnetic
induction topogram is typical of magnetic print strokes with a highly triangular or trapezoidal
cross-section (a distinctive feature of gravure printing, such as intaglio) At the same
time, the counterfeit banknote (A) has scarcer and smaller (low energy) contours of lines
with equal magnetic induction, concentrated along the edges of magnetic ink strokes
Such magnetic induction topogram is typical of magnetic print strokes with a attened
rectangular cross-section (a distinctive feature of letterpress and printer printing)
Since small print details such as the cross-sectional prole of magnetic ink were examined
in Fig 12, the compared accumulated magneto-optical images were examined under
magnication (button on the CADR toolbar)
Another tool which can be used for examination of topograms of accumulated magneto-
optical images is graphs of induction in the specied sections (Fig 13)
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