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Description  |
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BACKGROUND OF THE INVENTION
Main advantages of the banking system, utilizing the said credit card are
as follows:
a. The card is simple and inexpensive in production.
b. The card and approving device are universal and simple in use.
c. The card, being devoid of any surface information, provides the
unambiguous, automatic, real-time authentication and verification of the
user. The probability of accidental misuse is no higher then 10.sup.-7 .
d. The card is absolutely foolproof from stealing.
e. In combination with the suggested techniques the system becomes
absolutely protected from forging, even if the principle of the card
protection is known. The forging can be realized with information from the
bank computor memory only.
f. The approval device is small, self-consistent, universal and
unexpensive. Being realised in the form of solid-state optics, it can be
incorporated in all the applications, including even personal phone-sets,
paid-phones, bar-code counters, etc.
g. The card can include the additional sheltering information of any degree
of graphical complexity. Said information doesn't affect either time or
complexity of the card itself, the approval device, or authorization time.
h. All the approval procedures in all the applications are absolutely
automatic and the existing communication channels/lines for banking
information are being utilized.
Fingerprint being the most representative and informative natural object
numerous attempts were made to incorporate it in recognition devices.
Some number of correspondent inventions and patents exist, some of them
recently granted.
The said patents can be divided into two main categories: with computer
correlation and with elements of optical processing.
Devices from the secondary category even include in some cases coherent
sourse of illumination (see, for instance, Hartwig Ruell, U.S. Pat. No.
4,532,508).
In the computerized recognition systems with fingerprint as the approval
element (see, for instance, Arthur B. Carrol, et al., U.S.Pat. No.
4,684,801) the input fingerprint is usually introduced to the display
window and scanned. The scanned data is then directed to the processor and
compared with the set of fingerprints, already being stored.
One should realise that the informational volume for such informative
object as fingerprint usually demand all operative memory of processor. So
the prestored fingerprints use the long-time storage media (discs, tapes,
etc), needed data being introduced on demand. Corresponding time lapses
exist even for the most powerfull computers and are usually not mentioned
in these patent claims.
In some of the patents the elements of coherent processing are indirectly
used, even for the credit card approval (see Paul B. Elmes, U.S. Pat. No.
4,455,083), though in them the said elements are utilized in fingerprints
superimposing only, the advantages of Fourier spectra analysis not
incorporated.
In all the recently claimed of these patents the main problem of
authentication--positioning of fingerprints--is silently realised.
Inventors are trying to bypass it with the variety of different means,
including the rotation of light source (Paul A. Hakenewerth, U.S. Pat. No.
4,684,802), scanners of different levels of complexity (see Robert F.
Bunn, U.S. Pat. No. 4,641,350), means for mechanical rotation of the
fingerprints, and even including the grooves for input fingerprint
positioning.
It should be noted here, that for computerized systems, the said
positioning of the fingerprints is being realized electronically, each new
position of the input fingerprint being treated as the new input object.
This either increases greatly the processing time, or--the rather
elaborate and time consuming algorithms are being incorporated.
In the mostly recent granted patents, utilizing the holographic storage and
even the "modulated reference wave", (see U.S. Pat. Nos. 4,532,508, and
4,385,831) the possibilites and advantages of coherent processing are not
employed, correlation procedures not being optically incorporated.
The task being very attractive, some optical systems utilize the
fiber-optics elements (Robert F. Dowling, U.S. Pat. No. 4,785,171) and,
independently the patents for non-optical fingerprint recognition systems
exist (see Otmar Kern, U.S. Pat. No. 4,541,112; David G. Edwards, U.S.
Pat. No. 4,429,413).
All the mentioned disadvantages are being eliminated in the system under
claim. Due to application in it by the very simple and real-time
procedures, the spatial invariance and multi-step fully optical
correlation procedures are incorporated.
The system under claim uses for synthesizes the previous numerous
publications of the inventor (see, for instance J. S. Barbanell, Analysis
of optical correlator for fingerprints, Papers of Institute of
Radioengineering, p.202, 1972, Leningrad; J. S. Barbanell. Autometry, #5,
14, 1975, J. S. Barbanell et. al, invention certificates: #312,282, 1968,
Lenseless Optical Correlator for Fingerprints, #528,605 and 528,611
(1980)-Coherent Matched Filter with Optical Feedback).
SUMMARY OF THE INVENTION
This invention relates in general to credit cards banking systems and in
particular to an automatic holographic credit card with automatical
verification by the user, utilizing known coherent pattern recognition
techniques.
The primary object of the present invention is to provide a a foolproof
system for authentication of the said credit card, possessing the input
element that provides a real-time angular-invariant unique identification
of an authorized user, such as a fingerprint or other unique
identification, to approve the credit card on the first stage.
A further object of the invention is to provide an inexpensive holographic
credit card which utilizes holographically encoded particular fingerprint
of an authorized user which is optically continuously compared to the
presented rotating fingerprint and which authorizes the command signal to
the bank computer only when the presented fingerprint correlates with the
stored fingerprint.
A further object of the invention is to provide holographic credit card in
which the stored fingerprint of the authorized user may be readily changed
by the user.
A further object of the invention is to provide, in one embodiment, triple
automatic authentication such as a first level requiring the fingerprint
of the authorized user, a second level requiring the digital information
to be automatically compared with the one stored in bank computer memory
and on third, by command feedback signal from the latter, requiring the
graphical information from the authorized user (in the form of
signature--or digits) and utilizing also the additional means of optical
comparison for the credit card approvement device to be activated.
A further still object of the invention is to provide for the said
triple-stage procedure the means of secure supplying the said graphical
information, utilizing the standard computer display, with required
information to be introduced from the standard keyboard, the third-level
authorization realised by the "reflectance input".
Further objects and advantages of the invention will become apparent from
the following description and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of the holographic credit card
approval system according to the present invention;
FIG. 2 is a schematic representation of the holographic credit card
approval system additionally showing how the complex spatial Fourier
transform of a fingerprint of an authorized user is registered by the user
himself on the storage medium within the approval system;
FIG. 3 illustrates schematically a second embodiment of the approving
system which employs double authentication features;
FIG. 4 illustrates schematically an embodiment of the approving system
which employs employs the triple authentication features, and
FIG. 5 illustrates schematically an embodiment of the approving system
which employs the triple authentication features utilizing the inner
graphical input element.
DETAILED DESCRIPTION
The holographic credit card approval device shown in FIG. 1 may be
incorporated in any sort of applications of financial transactions. The
claimed devices possessing automatical foolproof authorization, all the
said transaction can be realized automatically. In the following
description, for the sake of clearness, functioning of the claimed system
is explained on the example of standard Day and Night Teller (DNT). In
other applications all the basical principles are preserved.
The system under claim includes a source of coherent light as for example a
laser 1. In low cost implementation, the source of coherent light for the
authentication step may be a source of partially coherent light such as a
neon lamp. (During the step of recording the fingerprint holographically,
the coherent light-source should always be used.) Thus the phrase
"coherent light-source" used here includes both coherent and partially
coherent light. Use of a laser provides a very small probability of error
at a significant cost compared to a neon lamp but is justified in many
applications of the invention by the said probability of error.
The usage of holographically encoded (conjugate) Fourier transforms (and
not the images themselves) is fully justified and not discussed here, as
the practice being discussed in detail is already approved and widely
realized in the numerous applications of the pattern recognition
techniques. Some advantages should be named such as the invariance of the
in-plane filter's orientation. Also, using such an informative object as
the fingerprint, only about 1% of initial fingerprint is needed for
assured recognition.
The holograms themselves are being applied in the credit cards production.
Those used, though, are thick-layer art holograms, does not carry any
functional obligations and are used for fashion and art purposes only.
Claimed card and the corresponding means provide inexpensively both the
card and corresponding additional approvement devices for the universal
automatic and global banking system. The latter incorporates the existing
communication channels, thus representing the most attractive features in
the terms of additional investments--the implementation of the new or
different channels being mostly expensive.
The card and approvement system under claim with fiber optics communication
channels, its advantages becoming increasingly profitable--then the
inverse transform "light-electrical signal" can be produced in the bank
computer.
Claimed credit cards, being used in the payed phones, for instance, the
second- and third-level approvement information, being small in volume,
can be directed to the bank computer by the same phone line.
The card is immediately compatible with the existing Bar Code Scanners, the
purchase procedures becoming automatic and foolproof. The compatibility is
readily realised, the Bar Scanners already possessing lasers and
auxilliary equipment. The differences will be represented by one/two
miirors and spherical lens only.
The system under claim, being inexpensive, automatic, universal and
foolproof both from misuse or forging, can find immediate implementation
in compatibility with the UNICARD, which is being incorporated now.
In the said cards, which already utilize the microprocessor and input
keyboard, the one- or two-level devices under claim can be readily
incorporated. Mentioned above the very low probability of false
recognition provides the needed security and makes both the card foolproof
from misuse and the personal code obsolete.
Procedures being discussed below are utilized in coherent pattern
recognition techniques, but in all the applications of the latter, the
main problem is that the accuracy of recognition (approvement) is greatly
dependent on the placement of the matched filter (or on the relative
orientation of the input object and corresponding matched filter).
The recognition system (claimed holographic credit card approval system) is
very sensitive to the relative angular orientation of the matched filter,
being incorporated in the credit card itself and the object under
recognition, i.e. the fingerprint of the user.
This produces the main and the biggest problem to the real-time automatic
recognition in all the existing optical pattern recognition system. In the
claimed system the inventor deals with the said problem in the most simple
an efficient way.
To realize this procedure in the simplest way the approval (recognition)
system includes the input element in the form of a transparent window 4.
This element makes it possible to overcome the main disadvantages of prior
similar systems by providing the means for the real-time angular matching
of the spectra orientation that makes the system real-time functionable.
Against this element 4 the user places the tip of a particular finger 6
for identification purposes and, optionally, to activate the light source
1.
The light from the source 1 illuminates fingertip 6, and the light
reflected from the fingertip as an encoded beam 2 passes through the
spherical lens 5 which projects the said beam upon the matched filter 3,
located at its shadow plane. Matched filter 3 represents the complex
spatial Fourier transform of the image of the subject's fingerprint,
having been produced with the coherent light on any suitable recording
medium such as photographic, thermoplastic or photothermoplastic media.
The said filter is structurally included in the holographic credit card
itself.
In use, the user rotates the fingertip 6 in order to align the
Fourier-transform of introduced fingerprint with the stored holographic
representation of the authorized fingerprint in matched filter 3, being
located in the credit card, and in that way to eliminate the main,
mentioned disadvantage of the system.
The correlation procedures are realized continuously in time until the
images are angularly matched and the correlation signal is being formed.
The Fourier-spectrum comparison provides the invariance to the in-plane
displacements of the introduced image and invariance to the in-plane scale
differences. The chosen procedure provides automatically the formation of
the correlation signal inside of the wavefront, the procedure being
absolutely real-time, as a result of the implementation of the
two-dimensional spatial comparison.
Two additional sources of displacement errors are treated as follows.
The correlation signal is greatly dependent on in-focal orientation of the
matched filter 3. The latter is avoided by the following.
The filter should be fitted exactly in the back focal plane of lens 5 in
the approvement device. That can be easily achieved by different methods.
Only two of them should be itemized:
(a) The approval system is supplied with grooves, the produced holographic
credit card possessing enough thickness and mechanical firmness to fit
exactly in the latter. The said card being prepared in the accustomed
form, on plastic, these requirements are easily achieved. It should be
mentioned here, that the said filter, included in the card can be produced
on the standard film--transmitting modification. Then--for the sakes of
mentioned mechanial firmness, the innventor suggests the card to be
covered with melted plastic. The latter should not be necessarily
transparent in the visual wave-band. For the security increase the
inventor suggest it to be transparent in different wave-band, the laser
for read-out with corresponding light-wave supplied.
The filter can be realised in the reflecting modification also: with the
use of phase holograms. In the latter case, the recognition (approval)
procedure is totally unaffected by the mechanical damages to the card of
any sort (except lamination): to the extent, that the card can be even
scratched/scraped. This filter can be produced by the known bleaching
procedures, or by mechanical printing on plastic card under the
preparation.
(b) The system being optically reversible, the approval device itself is
used for filter preparation.
The linear shifts (misplacements) of the matched filter in the back focal
plane of the lens 5 absolutely do not affect the recognition procedure.
This feature is used on the secondary levels of the suggested recognition
procedure.
In the shadow plane of the matched filter 3 a photosensitive element 7 is
located. Its output command signal is connected to a control
device/element which approves the use of the said credit card on the first
level of recognition.
For further functional improvement the device may additionally include a
second spherical lens (shown by dotted lines) which is situated in such a
way that the matched filter is in the front and the photodetector is in
the rear focal planes of said lens correspondingly. The functions of said
lens are to focus the signal of correlation, is any, on the surface of
photodetector.
The correlation signal's orientation in the said plane is unambiguously
defined by the angular orientation of the reference beam during the stage
of the matched-filter preparation. The correlation optical signal, if any,
appears in the exact geometrical point of the said back focal plane. This
can additionally serve as a protective measure, while the angle of
reference wave orientation is being kept secure. This feature can be
utilized in the second-level procedure, discussed below.
Thus the photoelement 7 can be located in the fixed position, and the
optical part of the approval device becomes easily realizable in the form
of the solid-state optics.
Photoelement 7 serves the purpose of registering the formed correlation
signal and generates the electrical output command signal when the
correlation signal between the stored and introduced fingerprints is
present. As the correlation signal in the single stage approval device
will always be a bright spot (plane reconstructed wave, or the
Delta-function after additional focusing), it can be registered by the
simple and inexpensive photosensitive means.
In a recognition mode of operation, the user insert his holographic credit
card in the corresponding standard slit. The card being itserted, it
activates the laser. It also can be activated by pressing the user's
finger against the transparent window 4. The reflected light beam 2, being
modulated in amplitude by the said fingerprint 6, passes through the
spherical lens 5, which forms its complex Fourier spectrum in the plane of
matched optical filter 3. After lase activation the user rotates his
finger against transparent window 4, until the spectra coincide angularly.
If the spectra additionaly match, and only then, the correlation signal in
the form of a bright spot appears on the surface of photodetector 7.
The position of the said spot, if any, is unambiguously predetermined.
The process can be further improved by focusing the said correlation
signal. To achieve this a second focusing lens is added (shown by the
dotted lines). It is situated in such a way that the matched filter is in
the forward focal plane and the photosensor is in the rear focal plane of
the said second lens. The said photosensitive element 7 then generates the
command electrical signal as previously described.
By utilizing the user's fingerprint as the source of authentication, the
probability of error is of the order of 1 in 10,000,000. Using this
feature the device will still be functional even if only a small part of
the fingerprint is presented.
The recognition procedure is a real-time one and can be realized with the
speed of 10E-8 second.
The present invention eliminates the main problem of similar prior devices,
and that is the extreme sensitivity of the system to the input
fingerprint/filter relative angular orientation. This problem is solved by
the chosen input element--a transparent window 4 against which the user
rotates his finger. This causes the rotation of the corresponding spectrum
in the plane of matched filter 3 until the position of angular coincidence
is achieved. Then and only then the correlation peak is formed.
Rotation of the input fingerprint can be formally represented as a sequence
of separate recognition steps, each one being realized with practically
unlimited speed. In other words, the user can rotate his finger with any
speed he likes.
It should be noted that using self-developing registering media for the
matched filter, the user himself, fully automatically, can prepare the
needed filter using the claimed approval device.
The corresponding procedures are discussed in detail in the theory of
optical matched filtering. The thing to be emphasized is that the claimed
holographic credit card can be produced in a user-modifiable form, the
memory for matched filters being long-time, changeable and realized on the
reversible media optically.
Structurally, this changeability can be realized by adding an optical
switch which activates the reference beam during credit card preparation.
Such a switch can be connected to a knob on the outer side of the approval
device, with an instructional indication such as "prepare", for instance.
Using the self-developing registering media and applying the recognized
techniques, the named procedure can be made fully accomplished by the user
himself. This is done by using the additions to the system shown in FIG.
2.
In actual preparation of the card in the said way, the user presses his
fingerprint onto the input window of the lock, thus activating the laser.
(He receives confirmation that the laser has been activated by the
illumination of the said input window). Then the user switches on the
"prepare" knob, the reference beam becomes activated, and the Fourier
transform of his pressed finger is automatically implemented inside of the
credit card in the form of a matched optical filter. After the knob is
switched off, the card is absolutely ready and prepared for use--for the
recognition (approval) proceedings.
If preferred, the conventional and accustomed procedure can be utilized for
holographic credit card preparation. After the customer applies for the
credit card, the company mails him the medium, on which the user presses
his fingerprint and mails the imprint back. Then the card is manifactured,
the described above holographical and Fourier transforms being implemented
industrially. (This method is preferrable, when transform of a fingerprint
is realised in a form of printed on plastic phase hologram).
Though the verification procedures are absolutely foolproof from mistakes
within the limits of any known approving devices (with the stated earlier
probability of errors), additional preventive measures can be easily
suggested and incorporated.
Described credit card is absolutely foolprof from being stolen (or-misuses
being stolen). The additional steps of verification serve the purpose of
forge protection. All measures being utilized, the card can be forged with
use of information from bank computer memory only (the latter being highly
protected under all curcumstances).
For standard consumer needs, though, the inventor does not suggest their
implemention, as the approval devices and procedures become increasingly
complicated and expensive.
Said complexity should be understood in the relative terms--for the most
sophisticated device will be approximately the same as DNT, mentioned
before. These additional procedures does not leed to the complication of
the card itself.
For the modified approval devices, to be referred as to the "two-stage"
ones, the matched filter is prepared separately, the corresponding
technique being very simple. In creating the two-stage approval, during
the stage of matched filter preparation the so called "generalized
hologram" technique is applied. that means that the reference beam
includes an additional information carrier, whether transmitting or
reflecting. (For instance, additional information can be introduced by
computer display, the reference laser beam being reflected from its
surface).
By incorporating the optical processing, the said information can be of any
degree of graphic complexity. The simplest but most representative case of
including a code word is discussed below. The latter is chosen by the
inventor due to usual custom--the code word being the signature of the
user.
Another suggested type of the sheltering information, is the digital
sequense--in this case practically without the limitations--due to the
opertional speed of the system. For instance, the said sequence can
represent the account number of the user and can easily include 10-12
digits.
During the stage of matched filter preparation, the said sheltering
graphical information the user is included in the reference beam (by means
of a slide transparency, from the display, etc.). Then after the first
stage of recognition is concluded (i.e., fingerprints match), in the
predetermined position in the plane of the photodetector will appear not a
bright spot, but the image of the chosen code word--the signature, the
digital sequence, etc., having been previously included. (In this
modification the additional focusing of the correlation signal is not
needed).
This sheltering information is being read out consequently in time or space
(by the photodetector matrix, for inst.) and directed through the already
existing standard communication line to the bank computer. There it is
compared to the sheltering information being previously incorporated in
the credit card (in the reference beam of the spatial filter of it). If
the informational sequences match, computer produces the decision about
the required approvememt.
The advantages of suggested two-level approvement procedure are that the
mostly informative object (fingerprint) is being compared optically, that
leads to the high increase of the informational speed. Fingerprint being
most informative, it's processing on the computer represents bit
difficulties, the fingerprint possessing about of 2 Mbytes of
informational volume.
This double-level verification system for the said credit card (see FIG. 3)
includes the same elements, as the previously discussed, only ther
connection to the bank computer through the existing communication lines
is provided.
Utilizing the same principle (reference beam compression) the sheltering
information can be included in the encoded form in the angle of
propagation of the said beam on the step of filter preparation. Then on
the reconstruction step, the correlation dot, if any, will appear in the
exact spot of photodetector plane. The latter being realised in the form
of the two-dimensional matrix, this information is being read out and
directed through the communication line for computer comparison.
The system under claim provides the possibilites and means for yet further
verification, if the said suggested double-level procedure does not
provide the required security. (The probability of misuse of false
recognition for such informative object as fingerprint is negligible-eith
the stated before probability of error).
To exclude the probability of forging the triple-level system is claimed
also.
This system uses further the advantages of optical processing and realizes
by the feed-back computer signal, the optical correlation of the
sheltering information itself.
To realise this procedure an additional stage of optical filtering is added
(FIG. 4). Using the same principle, this modification includes: 1-laser,
3-"generalized" matched filter, 4 and 8-input elements, 5 and 10-spherical
lenses, 6-finger, 7-photoelement, with output connected to the control
device.
In this modification (see FIG. 4), the holographic credit card approval
system additionally includes the second input element 8, being situated on
the path of the optical beam co-axically. This window posses This element
serves the purposes of introducing in real-time the additioonal sheltering
information by the user himself for optical comparison with the sheltering
information, having been introduced in the reference beam of the filter.
After the first level (fingerprint) approvement is realised, and after the
second level (computer) is realised also, in case of doubts, computer
supplies the request--with the feedback signal through the same
communication line.
The user can be informed by the sign "more information", for instance,
fully in the same way, as the standard DNT functions. Then he introduces
the second identification (signature, digital sequence, etc.) to the
secong input element 8. The reconstructed after the first level reference
wave, if any, is modulated secondarily by this additional information and
is directed to the second spherical lens 10. Being correlated in the wave
front, this combined sheltering information is optically focused on the
surface of the second photodetector.
If the positive correlation exists (second bright spot) the second approval
command signal is being supplied by the said photodetector 7'.
Realisation of the second input element dictates the alternative decision.
For the sakes of better security it can be realised as the reflecting
one--in the form of the display, being situated inside of the approval
system. Then any printed or digital information can be introduced for
optical comparison directly from the keyboard, user punching the
corresponding keys, all the procedure being sheltered absolutely.
From other point of view, if more elaborate graphical information is
chosen, the user canwrite it down on the second input element. The
procedure being less secure (the information might be occasionally seen),
it can be represented by the two-dimensional graphical information of any
degree of complexity.
The latter does not affect the time of quality of third recognition step,
it being realised optically.
To provide the means of said comparison, the system with different second
input element 8 is also claimed (see FIG. 5). Also being connected to the
bank computer, this claimed system is secure enough independently--so the
communication lines to the computer are not necessarily required and are
shown on FIG. 5. by the dotted lines.
This triple-level modification includes: 1-laser, 3-"generalized" matched
filter, 4 and 8'-input elements (transparent windows), 5 and 10-spherical
lenses, 6-finger, 7-photoelement, with output connected to the control
device, and 9-rotating lid.
Here the input element is external and is realised as the second
transparent window 8', being situated on the path of the optical beam
co-axically. This window possesses lines/grooves for angular orientation
of the additional graphic information (in this particular case, the
signature of the user or his personal digital code, for instance).
To this window the movable lid 9 is attached. This lid has a triangular
cross-section with an arbitrary angle and a mirrored outer surface.
Following the input element 8, along the optical path of the beam, the
standard spherical lens 10 is located. The angular space orientation of
the latter's optical axis corresponds to the arbitrary (but fixed) angle
of the lid 9. In the back focal plane of this lens 10 on its optical axis
the standard photoelement 7' is located.
This triple-level device, using the generalized matched optical filter and
applying the two-stage Fourier optical recognition procedure, functions in
the following way.
a) Without the computer's approval
In actual operation the user writes down his signature on the second input
element 8 along the pre-positioned lines/grooves, then closes the lid and
presses his finger to the window 4. If the digital sheltering information
is used, the said window can include even thepre-grooved net--for better
positioning the figures. The lid 9 becomes locked until the credit card
returned. Locking the lid prevents the unauthorized person from reading
the sheltering information, which will appear if the imprint of the
fingerprint is forged
After this the user inserts his card and realises the procedure as in the
first modification.
The first stage of said recognition procedure is absolutely the same as in
the single stage approvement device, having been described earlier. After
the fingerprint is approved (and only in that case), the image of the
graphical sheltering information will appear on the inner plane of window
8. It should be noted here that the angular orientation of said
information's reconstructed image depends on the orientation of the
generalized matched optical filter only and is absolutely unaffected by
the rotational movement of the finger during the first approval stage.
After the first approval stage, the second identification image exactly
fits angularly the lines on the second window 8. To provide the assured
recognition on the second stage, angular discrepancies within the range of
10 degrees are absolutely allowable.
In some modifications of the device under discussion the user might be
provided with possibility to check that the first stage is finished (his
fingerprint is approved) by opening the lid 9 and checking if the image of
his signature has appeared. After the approval of the first stage, the
correlation light beam, already carrying the information about the
sheltering information reflected from the mirrored surface of the lid 9.
In the reflected beam the information about the said information, having
been written down manually on second input element 8 is multiplicatively
superimposed on the image of the first one. After passing the lens 10,
both images are correlated by their corresponding Fourier spectra, the
correlation signal to appear on the surface of the photodetector 7.
Fourier spectrum comparison is chosen and implemented because its results
are unaffected by the relative linear dimensions: to be approved the
initial (in the generalized matched filter) and written down signatures
need not linearily match exact | | |
