WORLD INTELLECTUAL PROPERTY ORGANIZATION
`International Bureau
`
`(11) International Publication Number:
`
`Al
`
`(43) International Publication Date:
`
`17 February 2000 (17.02.00)
`
`PCT
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`WO 00/08415
`(51) International Patent Classification 7 :
`G0lB 11/24, A61C 13/00, 19/04
`
`(21) International Application Number:
`
`PCT/IL99/00431
`
`(22) International Filing Date:
`
`5 August 1999 (05.08.99)
`
`(30) Priority Data:
`125659
`
`5 August 1998 (05.08.98)
`
`IL
`
`(71) Applicant (for all designated States except US): CADENT
`LTD. [IUIL]; Hamelacha Street 14, 60372 Or Yehuda (IL).
`
`(72) Inventors; and
`(75) Inventors/Applicants
`only):
`(for US
`BABA YOFF,
`Noam [IUIL]; Laskov Street 25, 58672 Holon (IL).
`GLASER-INBARI, Isaia [IUIL]; Hashnayim Street 24,
`53230 Givataim (IL).
`
`(74) Agent: REINHOLD COHN AND PARTNERS; P.O. Box 4060,
`61040 Tel-Aviv (IL).
`
`(81) Designated States: AE, AL, AM, AT, AU, AZ, BA, BB, BG,
`BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, EE, ES, FI,
`GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE,
`KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MD, MG,
`MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE,
`SG, SI, SK, SL, TJ, TM, TR, TT, UA, UG, US, UZ, VN,
`YU, ZA, ZW, ARIPO patent (GH, GM, KE, LS, MW, SD,
`SL, SZ, UG, ZW), Eurasian patent (AM, AZ, BY, KG, KZ,
`MD, RU, TJ, TM), European patent (AT, BE, CH, CY, DE,
`DK, ES, Fl, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE),
`OAPI patent (BF, BJ, CF, CG, Cl, CM, GA, GN, GW, ML,
`MR, NE, SN, TD, TG).
`
`Published
`With international search report.
`Before the expiration of the time limit for amending the
`claims and to be republished in the event of the receipt of
`amendments.
`
`(54) Title: IMAGING A THREE-DIMENSIONAL STRUCTURE BY CONFOCAL FOCUSSING AN ARRAY OF LIGHT BEAMS
`
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`1
`
`(57) Abstract
`
`A
`
`B
`
`Determining surface topology of a portion (26) of a three-dimensional structure is provided. An array of incident light beams (36)
`passing through a focusing optics ( 42) and a probing face is shone on said portion. The focusing optics defines one or more focal planes
`forward the probing face in a position which can be changed (72) by the focusing optics. The beams generate illuminated spots (52) on the
`structure and the intensity of returning light rays propagating in an optical path opposite to that of the incident light rays is measured (60)
`at various positions of the focal plane(s). By determining spot-specific positions yielding a maximum intensity of the returned light beams,
`data is generated which is representative of said topology. Measurement of teeth. Light beams by grating of matrix of pinholes, micro lens
`array. Simultaneous imaging from three angles. Quicker with three different light components.
`
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`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.
`
`AL
`AM
`AT
`AU
`AZ
`BA
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`CF
`CG
`CH
`CI
`CM
`CN
`cu
`CZ
`DE
`DK
`EE
`
`Albania
`Annenia
`Austria
`Australia
`Azerbaijan
`Bosnia and Herzegovina
`Barbados
`Belgium
`Burkina Faso
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Central African Republic
`Congo
`Switzerland
`Cclte d'Ivoire
`Cameroon
`China
`Cuba
`Czech Republic
`Gennany
`Denmark
`Estonia
`
`ES
`FI
`FR
`GA
`GB
`GE
`GH
`GN
`GR
`HU
`IE
`IL
`IS
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LC
`LI
`LK
`LR
`
`Spain
`Finland
`France
`Gabon
`United Kingdom
`Georgia
`Ghana
`Guinea
`Greece
`Hungary
`Ireland
`Israel
`Iceland
`Italy
`Japan
`Kenya
`Kyrgyzstan
`Democratic People's
`Republic of Korea
`Republic of Korea
`Kazakstan
`Saint Lucia
`Liechtenstein
`Sri Lanka
`Liberia
`
`LS
`LT
`LU
`LV
`MC
`MD
`MG
`MK
`
`ML
`MN
`MR
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`RO
`RU
`SD
`SE
`SG
`
`Lesotho
`Lithuania
`Luxembourg
`Latvia
`Monaco
`Republic of Moldova
`Madagascar
`The fonner Yugoslav
`Republic of Macedonia
`Mali
`Mongolia
`Mauritania
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zealand
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapore
`
`SI
`SK
`SN
`sz
`TD
`TG
`TJ
`TM
`TR
`TT
`UA
`UG
`us
`uz
`VN
`YU
`zw
`
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Turkmenistan
`Turkey
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`Yugoslavia
`Zimbabwe
`
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`WO 00/08415
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`. 1 .
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`PCT /IL99/00431
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`IMAGING A THREE-DIMENSIONAL STRUCTURE BY CONFOCAL FOCUSSING AN
`ARRAY OF LIGHT BEAMS
`
`FIELD OF THE INVENTION
`
`This invention in the field of imaging techniques and relates to a
`
`method and an apparatus for non-contact imaging of three-dimensional
`
`structures, particularly useful for direct surveying of teeth.
`
`5 BACKGROUND OF THE INVENTION
`
`A great variety of methods and systems have been developed for direct
`
`optical measurement of teeth and the subsequent automatic manufacture of
`
`dentures. The term "direct optical measurement" signifies surveying of teeth
`
`in the oral cavity of a patient. This facilitates the obtainment of digital
`
`10 constructional data necessary for the computer-assisted design (CAD) or
`
`computer-assisted manufacture (CAM) of tooth replacements without having
`
`to make any cast impressions of the teeth. Such systems typically includes an
`
`optical probe coupled to an optical pick-up or receiver such as charge coupled
`
`device (CCD) and a processor implementing a suitable image processing
`
`15
`
`technique to design and fabricate virtually the desired product.
`
`One conventional technique of the kind specified is based on a
`
`laser-triangulation method for measurement of the distance between the
`
`surface of the tooth and the optical distance probe, which is inserted into the
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`. 2.
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`PCT /IL99/0043 l
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`oral cavity of the patient. The main drawback of this technique consists of the
`
`following. It is assumed that the surface of the tooth reflects optimally, e.g.
`
`Lambert's reflection. Unfortunately, this is not the case in practice and often
`
`the data that is obtained is not accurate.
`
`5
`
`Other techniques, which are embodied in CEREC-1 and CEREC-2
`
`systems commercially available from Siemens GmbH or Sirona Dental
`
`Systems, utilize the light-section method and phase-shift method, respectively.
`
`Both systems employ a specially designed hand-held probe to measure the
`
`three-dimensional coordinates of a prepared tooth. However, the methods
`
`10
`
`require a specific coating (i.e. measurement powder and white-pigments
`
`suspension, respectively) to be deposited to the tooth. The thickness of the
`
`coating layer should meet specific, difficult to control requirements, which
`
`leads to inaccuracies in the measurement data.
`
`By yet another technique, mapping of teeth surface is based on
`
`15 physical scanning of the surface by a probe and by determining the probe' s
`
`position, e.g. by optical or other remote sensing means, the surface may be
`
`imaged.
`
`U.S. Patent No. 5,372,502 discloses an optical probe
`
`for
`
`three-dimensional surveying. The operation of the probe is based on the
`
`20
`
`following. Various patterns are projected onto the tooth or teeth to be
`
`measured and corresponding plurality of distorted patterns are captured by the
`
`probe. Each interaction provides refinement of the topography.
`
`SUMMARY OF THE INVENTION
`
`The present invention is directed to a method and apparatus for
`
`25
`
`imaging three-dimensional structures. A preferred, non-limiting embodiment,
`
`is concerned with the imaging of a three-dimensional topology of a teeth
`
`segment, particularly such where one or more teeth are missing. This may
`
`allow the generation of data for subsequent use in design and manufacture of,
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`PCT/IL99/00431
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`for example, prosthesis of one or more teeth for incorporation into said teeth
`
`segment. Particular examples are the manufacture of crowns or bridges.
`
`The present invention provides, by a first of its aspects, a method for
`
`determining surface topology of a portion of a three-dimensional structure,
`
`5 compnsmg:
`
`(a) providing an array of incident light beams propagating in an
`
`optical path leading through a focusing optics and a probing face;
`
`the focusing optics defining one or more focal planes forward said
`
`probing face in a position changeable by said optics, each light
`
`10
`
`beam having its focus on one of said one or more focal plane; the
`
`beams generating a plurality of illuminated spots on the structure;
`
`(b) detecting intensity of returned light beams propagating from each
`
`of these spots along an optical path opposite to that of the incident
`
`light;
`
`15
`
`(c)
`
`repeating steps (a) and (b) a plurality of times, each time changing
`
`position of the focal plane relative to the structure; and
`
`(d) for each of the illuminated spots, determining a spot-specific
`
`position, being the position of the respective focal plane, yielding a
`
`maximum measured intensity of a respective returned light beam;
`
`20
`
`and
`
`( e) based on the determined spot-specific positions, generating data
`
`representative of the topology of said portion.
`
`By a further of its aspects, the present invention provides an
`
`apparatus
`
`for determining
`
`surface
`
`topology of a portion of a
`
`25
`
`three-dimensional structure, comprising:
`
`- a probing member with a sensing face;
`
`- an illumination unit for providing an array of incident light beams
`
`transmitted towards the structure along an optical path through said
`
`probing unit to generate illuminated spots on said portion;
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`- a light focusing optics defining one or more focal planes forward said
`
`probing face at a position changeable by said optics, each light beam
`
`having its· focus on one of said one or more focal plane ;
`
`- a translation mechanism coupled to said focusing optics for displacing said
`
`5
`
`focal plane relative to the structure along an axis defined by the
`
`propagation of the incident light beams;
`
`- a detector having an array of sensing elements for measuring intensity of
`
`each of a plurality of light beams returning from said spots propagating
`
`through an optical path opposite to that of the incident light beams;
`
`10
`
`- a processor coupled to said detector for determining for each light beam a
`
`spot-specific position, being the position of the respective focal plane of
`
`said one or more focal planes yielding maximum measured intensity of the
`
`returned light beam, and based on the determined spot-specific positions,
`
`generating data representative of the topology of said portion.
`
`15
`
`The probing member, the illumination unit and the focusing optics
`
`and the translation mechanism are preferably included together in one device,
`
`typically a hand-held device. The device preferably includes also the detector.
`
`The determination of the spot-specific positions in fact amounts to
`
`determination of the in-focus distance. The determination of the spot-specific
`
`20 position may be by measuring the intensity per se, or typically is performed
`
`by measuring the displacement (S) derivative of the intensity (I) curve (dI/dS)
`
`and determining the relative position in which this derivative function
`
`indicates a maximum maximum intensity. The term "spot-specific position
`
`(SSP) " will be used to denote the relative in-focus position regardless of the
`
`25 manner in which it is determined. It should be understood that the SSP is
`
`always a relative position as the absolute position depends on the position of
`
`the sensing face. However the generation of the surface topology does not
`
`require knowledge of the absolute position, as all dimensions in the cubic
`
`field of view are absolute.
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`The SSP for each illuminated spot will be different for different spots.
`
`The position of each spot in an X-Y frame of reference is known and by
`
`knowing the relative positions of the focal plane needed in order to obtain
`
`maximum intensity (namely by determining the SSP) , the Z or depth
`
`5 coordinate can be associated with each spot and thus by knowing the X-Y-Z
`
`coordinates of each spot the surface topology can be generated.
`
`In accordance with one embodiment, in order to determine the Z
`
`coordinate (namely the SSP) of each illuminated spot the position of the focal
`plane is scanned over the entire range of depth or Z component possible for
`
`10
`
`the measured surface portion. In accordance with another embodiment the
`
`beams have components which each has a different focal plane. Thus, in
`
`accordance with this latter embodiment by independent determination of SSP
`
`for the different light components, e.g. 2 or 3 with respective corresponding 2
`
`or 3 focal planes, the position of the focal planes may be changed by the
`
`15
`
`focusing optics to scan only part of the possible depth range, with all focal
`
`planes together covering the expected depth range. In accordance with yet
`
`another embodiment, the determination of the SSP involves a focal plane scan
`
`of only part of the potential depth range and for illuminated spots where a
`
`maximum illuminated intensity was not reached, the SSP is determined by
`
`20 extrapolation from the measured values or other mathematical signal
`
`processing methods.
`
`The method and apparatus of the invention are suitable for determining
`
`a surface topology of a wide variety of three-dimensional structures. A
`
`preferred implementation of method and apparatus of the invention are in
`
`25 determining surface topology of a teeth section.
`
`In accordance with one embodiment of the invention, the method and
`
`apparatus are used to construct an object to be fitted within said structure. In
`
`accordance with the above preferred embodiment, such an object is at least
`
`one tooth or a portion of a tooth missing in the teeth section. Specific
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`PCT /IL99/00431
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`examples include a crown to be fitted on a tooth stump or a bridge to be fitted
`
`within teeth.
`
`By one embodiment of the invention, the plurality of incident light
`
`beams are produced by splitting a parent beam. Alternatively, each incident
`
`5
`
`light beam or a group of incident light beams may be emitted by a different
`
`light emitter. In accordance with a preferred embodiment, light emitted from a
`
`light emitter passes through a diffraction or refraction optics to obtain the
`
`array of light beams.
`
`In accordance with one embodiment, the parent light beam is light
`
`10 emitted from a single light emitter. In accordance with another embodiment,
`
`the parent light beam is composed of different light components, generated by
`
`different light emitters, the different light components differing from one
`
`another by at least one detectable parameter. Such a detectable parameter may,
`
`for example be wavelength, phase, different duration or pulse pattern, etc.
`
`15 Typically, each of said light components has its focus in a plane differently
`
`distanced from the structure than other light components. In such a case, when
`
`the focal plane of the optics is changed, simultaneously the different ranges of
`
`depth ( or Z component) will be scanned. Thus, in such a case, for each
`
`illuminated spot there will be at least one light component which will yield a
`
`20 maximum intensity, and the focal distance associated with this
`
`light
`
`component will then define the Z component of the specific spot.
`
`In accordance with an embodiment of the invention the incident light
`
`beams are polarized. In accordance with this embodiment, typically the
`
`apparatus comprises a polarization filter for filtering out, from the returned
`
`25
`
`light beams, light components having the polarization of the incident light,
`
`whereby light which is detected is that which has an opposite polarization to
`
`that of the incident light.
`
`The data representative of said topology may be used for virtual
`
`reconstruction of said surface topology, namely for reconstruction within the
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`PCT /IL99/00431
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`computer environment. The reconstructed topology may be represented on a
`
`screen, may be printed, etc., as generally known per se. Furthermore, the data
`
`representative of said topology may also be used for visual or physical
`
`construction of an object to be fitted within said structure. In the case of the
`
`5 preferred embodiment noted above, where said structure is a teeth section
`
`with at least one missing tooth or tooth portion, said object is a prosthesis of
`
`one or more tooth, e.g. a crown or a bridge.
`
`By determining surface topologies of adjacent portions, at times from
`
`two or more different angular locations relative to the structure, and then
`
`10 combining such surface topologies, e.g in a manner known per se, a complete
`
`three-dimensional representation of the entire structure may be obtained. Data
`
`representative of such a representation may, for example, be used for virtual
`
`or physical reconstruction of the structure, may be transmitted to another
`
`apparatus or system for such reconstruction, e.g. to a CAD/CAM apparatus.
`
`15 Typically, but not exclusively, the apparatus of the invention comprises a
`
`communication port for connection to a communication network which may
`
`be a computer network, a telephone network, a wireless communication
`
`network, etc.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`20
`
`In order to understand the invention and to see how it may be carried
`
`out in practice, a preferred embodiment will now be described, by way of
`
`non-limiting example only, with reference to the accompanying drawings, in
`
`which:
`Figs. lA and lB are a schematic illustration by way of a block diagram
`
`25 of an apparatus in accordance with an embodiment of the invention (Fig. lB
`
`is a continuation ofFig. IA);
`Fig. 2A is a top view of a probing member in accordance with an
`
`embodiment of the invention;
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`Fig. 2B is a longitudinal cross-section through line II-II in Fig. 2A,
`
`depicting also some exemplary rays passing therethrough;
`
`Fig. 3· is a schematic illustration of another embodiment of a probing
`
`member; and
`
`5
`
`Fig. 4 is a schematic illustration of an embodiment where the parent
`
`light beam, and thus each of the incident light beams, is composed of several
`
`light components, each originating from a different light emitter.
`
`DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
`
`10
`
`Reference is first being made to Figs. IA and lB illustrating, by way
`
`of a block diagram an apparatus generally designated 20, consisting of an
`
`optical device 22 coupled to a processor 24. The embodiment illustrated in
`
`Fig. 1 is particularly useful for determining the three-dimensional structure of
`
`a teeth segment 26, particularly a teeth segment where at least one tooth or
`
`15 portion of tooth is missing for the purpose of generating data of such a
`
`segment for subsequent use in design or manufacture of a prosthesis of the
`
`missing at least one tooth or portion, e.g. a crown or a bridge. It should
`
`however be noted, that the invention is not limited to this embodiment, and
`
`applies, mutatis mutandis, also to a variety of other applications of imaging of
`
`20
`
`three-dimensional structure of objects, e.g. for the recordal or archeological
`
`objects, for imaging of a three-dimensional structure of any of a variety of
`
`biological tissues, etc.
`
`Optical device 22 comprises, m this specific embodiment, a
`
`semiconductor laser unit 28 emitting a laser light, as represented by arrow 30.
`
`25 The light passes through a polarizer 32 which gives rise to a certain
`
`polarization of the light passing through polarizer 32. The light then enters
`
`into an optic expander 34 which improves the numerical aperture of the light
`
`beam 30. The light beam 30 then passes through a module 38, which may, for
`
`example, be a grating or a micro lens array which splits the parent beam 30
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`into a plurality of incident light beams 36, represented here, for ease of
`
`illustration, by a single line. The operation principles of module 38 are known
`
`per se and the art and these principles will thus not be elaborated herein.
`
`The light unit 22 further comprises a partially transparent mirror 40
`
`5 having a small central aperture. It allows transfer of light from the laser source
`
`through the downstream optics, but reflects light travelling in the opposite
`
`direction. It should be noted that in principle, rather than a partially
`
`transparent mirror other optical components with a similar function may also
`
`be used, e.g. a beam splitter. The aperture in the mirror 40 improves the
`
`10 measurement accuracy of the apparatus. As a result of this mirror structure the
`
`light beams will yield a light annulus on the illuminated area of the imaged
`
`object as long as the area is not in focus; and the annulus will turn into a
`
`completely illuminated spot once in focus. This will ensure that a difference
`
`between the measured intensity when out-of- and in-focus will be larger.
`
`15 Another advantage of a mirror of this kind, as opposed to a beam splitter, is
`
`that in the case of the mirror internal reflections which occur in a beam splitter
`
`are avoided, and hence the signal-to-noise ratio improves.
`
`The unit further comprises a confocal optics 42, typically operating
`
`in a telecentric mode, a relay optics 44, and an endoscopic probing member
`
`20 46. Elements 42, 44 and 46 are generally as known per se. It should
`
`however
`
`be
`
`noted
`
`that
`
`telecentric
`
`confocal
`
`optics
`
`avoids
`
`distance-introduced magnification changes and maintains
`
`the same
`
`magnification of the image over a wide range of distances in the Z direction
`
`(the Z direction being the direction of beam propagation). The relay optics
`
`25 enables to maintain a certain numerical aperture of the beam's propagation.
`
`The endoscopic probing member typically comprises a rigid,
`
`light-transmitting medium, which may be a hollow object defining within it
`
`a light transmission path or an object made of a light transmitting material,
`
`e.g. a glass body or tube. At its end, the endoscopic probe typically
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`comprises a mirror of the kind ensuring a total internal reflection and which
`
`thus directs the incident light beams towards the teeth segment 26. The
`
`endoscope 46 thus emits a plurality of incident light beams 48 impinging on
`
`to the surface of the teeth section.
`
`5
`
`Incident light beams 48 form an array of light beams arranged in an
`
`X-Y plane, in the Cartasian frame 50, propagating along the Z axis. As the
`
`surface on which the incident light beams hits is an uneven surface, the
`
`illuminated spots 52 are displaced from one another along the Z axis, at
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`different (Xi,Yi) locations. Thus, while a spot at one location may be in
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`10
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`focus of the optical element 42, spots at other locations may be
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`out-of-focus. Therefore, the light intensity of the returned light beams (see
`
`below) of the focused spots will be at its peak, while the light intensity at
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`other spots will be off peak. Thus, for each illuminated spot, a plurality of
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`measurements of light intensity are made at different positions along the
`15 Z-axis and for each of such (Xi, YD location, typically the derivative of the
`intensity over distance (Z) will be made, the Zi yielding maximum
`
`derivative, Z0, will be the in-focus distance. As pointed out above, where, as
`a result of use of the punctured mirror 40, the incident light forms a light
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`disk on the surface when out of focus and a complete light spot only when
`
`20
`
`in focus, the distance derivative will be larger when approaching in-focus
`
`position thus increasing accuracy of the measurement.
`
`The light scattered from each of the light spots includes a beam
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`travelling initially in the Z axis along the opposite direction of the optical
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`path traveled by the incident light beams. Each returned light beam 54
`
`25 corresponds to one of the incident light beams 36. Given the unsymmetrical
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`properties of mirror 40, the returned light beams are reflected in the
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`direction of the detection optics generally designated 60. The detection
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`optics comprises a polarizer 62 that has a plane of preferred polarization
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`oriented normal to the plane polarization of polarizer 32. The returned
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`polarized light beam 54 pass through an imaging optic 64, typically a lens
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`or a plurality of lenses, and then through a matrix 66 comprising an array of
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`pinholes. CCD camera has a matrix or sensing elements each representing a
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`pixel of the image and each one corresponding to one pinhole in the array
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`5 66.
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`The CCD camera is connected to the image-capturing module 80 of
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`processor unit 24. Thus, each light intensity measured in each of the sensing
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`elements of the CCD camera, is then grabbed and analyzed, in a manner to
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`be described below, by processor 24.
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`10
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`Unit 22 further comprises a control module 70 connected to a
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`controlling operation of both semi-conducting laser 28 and a motor 72.
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`Motor 72 is linked to telecentric confocal optics 42 for changing the relative
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`location of the focal plane of the optics 42 along the Z-axis. In a single
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`sequence of operation, control unit 70 induces motor 72 to displace the
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`15 optical element 42 to change the focal plane location and then, after receipt
`
`of a feedback that the location has changed, control module 70 will induce
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`laser 28 to generate a light pulse. At the same time it will synchronize
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`image-capturing module 80 to grab data representative of the light intensity
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`from each of the sensing elements. Then in subsequent sequences the focal
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`20 plane will change in the same manner and the data capturing will continue
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`over a wide focal range of optics 44, 44.
`
`Image capturing module 80 is connected to a CPU 82 which then
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`determines the relative intensity in each pixel over the entire range of focal
`
`planes of optics 42, 44. As explained above, once a certain light spot is in
`
`25
`
`focus, the measured intensity will be maximal. Thus, by determining the Zi
`
`corresponding to the maximal light intensity or by determining the
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`maximum displacement derivative of the light intensity, for each pixel, , the
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`relative position of each light spot along the Z axis can be determined.
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`Thus, data representative of the three-dimensional pattern of a surface in the
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`teeth segment, can be obtained. This three-dimensional representation may
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`be displayed on a display 84 and manipulated for viewing, e.g. viewing
`
`from different angles, zooming-in or out, by the user control module 86
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`(typically a computer keyboard). In addition, the data representative of the
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`5 surface topology may be transmitted through an appropriate data port, e.g. a
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`modem 88, through any communication network, e.g. telephone line 90, to
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`a recipient (not shown) e.g. to an off-site CAD/CAM apparatus (not
`
`shown).
`
`By capturing, in this manner, an image from two or more angular
`
`10
`
`locations around the structure, e.g. in the case of a teeth segment from the
`
`buccal direction, from the lingal direction and optionally from above the
`
`teeth, an accurate three-dimensional representation of the teeth segment
`
`may be reconstructed. This may allow a virtual reconstruction of the three(cid:173)
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`dimensional structure in a computerized environment or a physical
`
`15
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`reconstruction in a CAD/CAM apparatus.
`
`As already pointed out above, a particular and preferred application
`
`is imaging of a segment of teeth having at least one missing tooth or a
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`portion of a tooth, and the image can then be used for the design and
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`subsequent manufacture of a crown or any other prosthesis to be fitted into
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`20
`
`this segment.
`
`Reference is now being made to Figs. 2A AND 2B illustrating a
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`probing member 90
`
`in accordance with one, currently preferred,
`
`embodiment of the invention. The probing member 90 is made of a light
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`transmissive material, typically glass and is composed of an anterior
`
`25
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`segment 91 and a posterior segment 92, tightly glued together in an
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`optically transmissive manner at 93. Slanted face 94 is covered by a totally
`
`reflective mirror layer 95. Glass disk 96 defining a sensing surface 97 is
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`disposed at the bottom in a manner leaving an air gap 98. The disk is fixed
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`in position by a holding structure which is not shown. Three light rays are
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`99 are represented schematically. As can be seen, they bounce at the walls
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`of the probing member at an angle in which the walls are totally reflective
`
`and finally bounce on mirror 94 and reflected from there out through the
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`sensing face 97. The light rays focus on focusing plane 100, the position of
`
`5 which can be changed by the focusing optics (not shown in this figure).
`
`Reference is now being made to Fig. 3, which is a schematic
`
`illustration of an endoscopic probe in accordance with an embodiment of
`
`the invention. The endoscopic probe, generally designated 101, has a
`
`stem 102 defining a light transmission path (e.g., containing a void
`
`10 elongated space, being made of or having an interior made of a light
`
`transmitting material. Probe 102 has a trough-like probe end 104 with two
`
`lateral probe members 106 and 108 and a top probe member 110. The
`
`optical fibers have light emitting ends in members 106, 108 and 110
`
`whereby the light is emitted in a direction normal to the planes defined by
`
`15
`
`these members towards the interior of the trough-like structure 104. The
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`probe is placed over a teeth segment 120, which in the illustrated case
`
`consists of two teeth 122 and 124, and a stamp 126 of a tooth for placement
`
`of a crown thereon. Such a probe will allow the simultaneous imaging of
`
`the surface topology of the teeth segment from
`
`three angles and
`
`20 subsequently the generation of a three-dimensional structure of this
`
`segment.
`
`Reference is now being made to Fig. 4. In this figure, a number of
`
`components of an apparatus generally designated 150 in accordance with
`
`another embodiment are shown. Other components, not shown, may be
`
`25
`
`similar to those of the embodiment shown in Fig. 1. In this apparatus a
`
`parent light beam 152 is a combination of light emitted by a number of laser
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`light emitters 154A, 154B and 154C. Optic expander unit 156 then expands
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`the single parent beam into an array of incident light beams 158. Incident
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`light beams pass through unidirectional mirror 160, then through optic
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`unit 162 towards object 164.
`
`The different light components composing parent beam 152 may for
`
`example be different wavelengths, a different one transmitted from each of
`
`5
`
`laser emitters 154A-C. Thus, parent light beam 152 and each of incident
`
`light beams 158 will be composed of three different light components. The
`
`image of the optics, or an optical arrangement associated with each of light
`
`emitters may be arranged such that each light component focuses on a
`different plane, PA, P8 and Pc, respectively. Thus in the position shown in
`10 Fig. 3, incident light beam 158A bounces on the surface at spot 170A which
`
`in the specific optical arrangement of optics 162 is in the focal point for
`
`light component A ( emitted by light emitter 154A). Thus, the returned light
`
`beam 172A, passing through detection optics 17 4 yield maximum measured
`
`intensity of light component A measured by two-di