(12) Unlted States Patent
`(10) Patent No.:
`US 8,638,447 B2
`
`Babayoff et al.
`(45) Date of Patent:
`Jan. 28, 2014
`
`USOO8638447B2
`
`(75)
`
`(54) METHOD AND APPARATUS FOR IMAGING
`THREE-DIMENSIONAL STRUCTURE
`.
`.
`InVemorSI Noam BabaYOffs RIShOH Le 21011 UL);
`15“ Glaser'lnbar" Gwatalm (IL)
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`r e u a(
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`73 A'
`)
`551gnee
`(
`( * ) Notice:
`
`(21) Appl.No.: 13/619,906
`
`(22)
`
`Filed:
`
`Sep. 14, 2012
`
`(65)
`
`Prior Publication Data
`
`US 2013/0094031 A1
`
`Apr. 18, 2013
`
`Related US. Application Data
`.
`.
`.
`.
`(60) Cont1nuation of applicatlon No. 13/082,623, filed on
`Apr. 8, 2011, now Pat. No. 8,310,683, which is a
`continuation of application No. 12/654,699, filed on
`Dec. 29, 2009, HOW Pat. NO. 7,944,569, which 15 a
`continuation of application No. 12/314,064, filed on
`Dec. 3, 2008, now Pat. No. 7,796,277, which is a
`continuation of application No. 11/652,055, filed on
`Jan. 11, 2007, now Pat. No. 7,477,402, which is a
`continuation of application No. 11/377,403, filed on
`Mar. 17, 2006, now Pat. No. 7,230,725, which is a
`continuation of application No. 11/175,186, filed on
`Jul. 7, 2005, now Pat. No. 7,092,107, which is a
`continuation of application No. 10/692,678, filed on
`Oct. 27, 2003, now Pat. No. 6,940,611, which is a
`diVision ofapplicationNo. 09/775,298, filed on Feb. 1,
`2001, now Fat. NO 6:697: 164, WhiCh is a continuation
`Of application NO- PCT/IL99/00431: filed on Aug. 5:
`1999'
`
`(30)
`
`F
`
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`t'
`orelgn pp 1ca 1011
`
`P ,
`'t D t
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`
`(51)
`
`(2006.01)
`
`Int. Cl.
`G013 11/24
`(52) US. Cl.
`USPC .......................................................... 356/609
`(58) Field of Classification Search
`USPC .......................................... 356/601, 603, 609
`See application file for complete search history.
`
`(56)
`
`References Cited
`US. PATENT DOCUMENTS
`
`3,013,467 A
`3,812,505 A *
`4,257,688 A
`4,443,706 A
`
`_
`12/1961 Mlnsky
`............................. 396/21
`5/1974 Elliott
`3/1981 Matsumura
`4/ 1984 DiMatteo et al.
`
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`DE
`
`4035799 A1
`19537586 A1
`
`5/1992
`4/1997
`
`.
`(Continued)
`
`OTHER PUBLICATIONS
`
`Benin, “Sensors,” 1996, p. 17.
`
`.
`(Commued)
`
`Primary ExamineriRoy MPunnoose
`(74) Attorney, Agent, or Firm 7 Wilson Sonsini Goodrich&
`Rosati
`
`ABSTRACT
`(57)
`An apparatus for determining surface topology ofa portion of
`a three-dimensional structure is provided, that includes a
`probing member, an illumination unit, a light focusing optics,
`atranslation mechanism, adetector andaprocessor.
`
`Aug. 5, 1998
`
`(IL) .......................................... 125659
`
`25 Claims, 5 Drawing Sheets
`
`1540
`
`U
`
`
`
`
`154
`
`3SHAPE EXHIBIT 1001
`3SHAPE EXHIBIT 1001
`3Shape v. Align
`3Shape V. Align
`IPR2019-00150
`IPR2019-00150
`
`

`

`US 8,638,447 B2
`
`Page 2
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`231/832 giirsnéi‘g? et 31'
`j’ggg’ggg :
`'
`’
`’
`7/1989 Keldermann et al.
`4’844’617 A
`8/1993 Derndinger et al.
`5’239’178 A
`5/1994 Kennedy
`5,312,249 A
`_
`8/1994 Wu et 31'
`53385198 A
`10/1994 Kobayash1 et 31'
`5’353’073 A
`53725502 A * 12/1994 Massen et 31'
`~~~~~~~~~~~~~~~~ 433/215
`53815236 A
`“1995 Morgan
`5,386,292 A
`1/1995 Massen et al.
`5,388,988 A
`2/1995 Goisser et 3L
`5,573,493 A
`11/1996 Sauer et 3L
`5,613,936 A *
`3/ 1997 Czarnek 6t 31.
`............... 600/166
`
`5,671,056 A *
`9/1997 Sato .........
`356/602
`5,737,084 A
`4/1998 Ishihara ........................ 356/609
`5,738,678 A
`4/1998 Patel
`5,801,880 A
`9/ 1998 Matsuda et al.
`6,263,234 B1
`7/2001 Engelhardt et a1.
`6,697,164 B1
`2/2004 Babayoff et al.
`6,885,464 B 1 *
`4/2005 Pfeiffer et 31.
`6,940,611 B2
`9/2005 Babayoff et a1.
`6,977,732 B2
`12/2005 Chen et al.
`7884215120 3%
`$588: 3:233:11: Z: :1 """"""" 356/609
`
`7:230:725 B2
`6/2007 Babayoff et al.
`7,319,529 B2 >x<
`1/2008 Babayoff ................ 356/601
`3:312:35 E; a
`$883 3:11:32: et a1................ 356/601
`7,630,089 B2
`12/2009 Babayoff et al.
`7’724’378 B2 *
`5/2010 Babayoff """"""""""" 356/601
`7’796’277 B2
`9/2010 Babayoff et al.
`7’944’569 B2
`5/201 1 Babayoff et al.
`7990548 BZ
`”011 Babayoff et al~
`8310583 B2
`1 1/2012 Babayoff et 3L
`
`................ 3 56/602
`
`*
`
`FOREIGN PATENT DOCUMENTS
`
`DE
`DE
`DE
`DE
`EP
`EP
`GB
`GB
`JP
`JP
`
`19627568 A1
`19638758 A1
`19640495 A1
`19650391 A1
`0278882 A1
`0679864 A1
`2144537 A
`2321517 A
`07-229720 A
`10-009827 A
`
`“1998
`3/1998
`“998
`6/1998
`8/1988
`11/1995
`3/1985
`7/1998
`8/1995
`1/1998
`
`W0
`W0
`W0
`
`6/1993
`WO 93/11403 A1
`10/1997
`WO 97/37264 A1
`6/1998
`WO 98/25171 A1
`OTHER PUBLICATIONS
`Gu et al., “Optimization ofaxial resolution in confocal imaging using
`annular pupils,” Optik, 1993, pp. 87-90, vol. 93.
`Ishihara et al., “High-speed 3D shape measurement using a non-
`scanning multiple-beam confocal imaging system,” SPIE, 1998, pp.
`68-75, V01. 3478
`Jervnall, J. and L. Selanne “Laser confocal microscopy and geo-
`graphic information systems in the study of dental morphology,”
`Palaeontologica electronica, 1999, vol. 2(1) [online] Retrieved from
`the Internet<URL:http://Www.biocenter.helsinki.fi/bi/evodevo/pdf/
`pe99.pdf>.
`Keyence America, “LT-9000 Series Lasar Displacement Sensor,”
`Produce Brochure. Dec. 26, 2006.
`Keyence, “How does the LT differ from conventional sensors?” Dec.
`26, 2006, pp, 2.3,
`Norman, et al., “The Fundamental Inventive Principles of CERBC
`CAD/CI Mand other CAD/CAM Methods,” 1996, pp. 81, 82, 88, 93.
`Okuda et al., “Evaluation of in vitro secondary caries using confocal
`laser scanning microscope and X-ray analytical microscope” Journal
`of Dentistry, 2003, p11 191-_196,V<)1_. 16(3)
`_
`_
`Preston eta1., “CAD/CAM in Dentistry,” Applied Optics, 1996, pp.
`77'77aV01~ 89~
`“
`_
`_
`_
`_
`_
`_
`Sheppa(r:d, etf al.,1 1\F/{hree-d1menls;(;r(1)aléfiiagtmg41n corifgcallgsniros-
`copy,
`on oca
`1croscopy,
`ap er
`, pp.
`,
`-
`,
`ca-
`demic Press Limited, San Diego, California, USA.
`Tiziani, et al., “Three:dimensional analysis by a microlens-array
`Ejnfocal arrangement, Applied Optics, 1994, pp. 567-572, vol. 33
`Tiziani, et _a1., “Three-dimensional
`image sensing by chromatic
`Efgfocal mlcroscopy, Applled Optlcs, 1994, pp. 1838-1843, vol. 33
`Watson, T.F. and A. Boyde, “Confocal light microscopic techniques
`for examining dental operative procedures and dental materials. A
`status report for the American Journal of Dentistry,” American Jour-
`na1 ofDentistry, 1991, pp. 193—200, vol. 4(4).
`Watson, T.F., “Applications of confocal scanning optical microscopy
`to dentistry,” British Dental Journal, 1991, pp. 287-291, vol. 171 (9).
`(Abstract only).
`Office action dated Feb. 25, 2008 for US. Appl. No. 11/652,055.
`Office action dated Apr. 2, 2012 for U.S.App1. No. 13/082,623.
`Office action dated Jun. 19, 2006 for U.S.App1. No. 11/377,403.
`Office action dated Sep. 1, 2010 for U.S.App1. No. 12/654,698.
`Offi
`.
`ce action dated Sep. 2, 2010 for US. Appl. No. 12/654,699.
`Office actlon dated Se . 29 2009 for US. A 1. No. 12/314 064.
`_
`P
`,
`PP
`,
`Office actlon dated Oct. 7, 2011 for U.S.App1. N0. l3/082,623.
`U.S. Appl. No. 13/784,511, filed Mar. 4, 2013, Babayoff et al.
`
`* cited by examiner
`
`

`

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`US. Patent
`
`Jan. 28, 2014
`
`Sheet 2 of5
`
`US 8,638,447 B2
`
`LINE
`
`TO
`TELEPHONE
`
`FIG. 1B
`
`

`

`US. Patent
`
`Jan. 28, 2014
`
`Sheet 3 of5
`
`US 8,638,447 B2
`
`FIG.2A
`
`FIGZB
`
`

`

`US. Patent
`
`Jan. 28, 2014
`
`Sheet 4 of5
`
`US 8,638,447 B2
`
`
`
`FIGS
`
`

`

`US. Patent
`
`Jan. 28, 2014
`
`Sheet 5 of5
`
`US 8,638,447 B2
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`154C
`
`1548
`/
`‘
`
`154A
`
`152
`
`156
`
`
`
`F104
`
`

`

`US 8,638,447 B2
`
`1
`METHOD AND APPARATUS FOR IMAGING
`THREE-DIMENSIONAL STRUCTURE
`
`CROSS-REFERENCE
`
`This application is a Continuation Application of US.
`patent application Ser. No. 13/082,623, filed onApr. 8, 2011,
`which was a Continuation Application of US. patent appli-
`cation Ser. No. 12/654,699, filed on Dec. 29, 2009, now US.
`Pat. No. 7,944,569 which was a Continuation Application of
`US. patent application Ser. No. 12/314,064, filed on Dec. 3,
`2008, now US. Pat. No. 7,796,277, which was a Continuation
`Application of US. patent application Ser. No. 11/652,055,
`filed on Jan. 11, 2007, now US. Pat. No. 7,477,402, which
`was a Continuation Application of US. patent application
`Ser. No. 11/377,403, filed on Mar. 17, 2006, now US. Pat.
`No. 7,230,725, which was a ContinuationApplication ofUS.
`patent application Ser. No. 11/175,186, filed on Jul. 7, 2005,
`now US. Pat. No. 7,092,107, which was a Continuation
`Application of US. patent application Ser. No. 10/692,678,
`filed on Oct. 27, 2003, now US. Pat. No. 6,940,611, which
`was a Divisional Application of US. patent application Ser.
`No. 09/775,298, filed on Feb. 1, 2001, now US. Pat. No.
`6,697,164, which was a Continuation Application of Interna-
`tional PCTApplication No. PCT/IL99/00431, filed onAug. 5,
`1999, which claims priority from Israeli Patent Application
`No. 125659, filed on Aug. 5, 1998, the content of each of
`which is hereby incorporated by reference in its entirety.
`
`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.
`
`BACKGROUND OF THE INVENTION
`
`A great variety of methods and systems have been devel-
`oped for direct optical measurement of teeth and the subse-
`quent 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
`constructional data necessary for the computer-assisted
`design (CAD) or computer-assisted manufacture (CAM) of
`tooth replacements without having to make any cast impres-
`sions 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 suit-
`able image processing technique to design and fabricate vir-
`tually the desired product.
`One conventional technique of the kind specified is based
`on a laser-triangulation method for measurement of the dis-
`tance between the surface ofthe tooth and the optical distance
`probe, which is inserted into the oral cavity ofthe 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.
`Other techniques, which are embodied in CEREC-l 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 require a specific coating (i.e. measurement pow-
`der and white-pigments suspension, respectively) to be
`
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`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 ofteeth surface is based
`on physical scanning of the surface by a probe and by deter-
`mining the probe’s position, e.g. by optical or other remote
`sensing means, the surface may be imaged.
`US. Pat. No. 5,372,502 discloses an optical probe for
`three-dimensional surveying. The operation of the probe is
`based on the 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 interac-
`tion provides refinement of the topography.
`
`SUMMARY OF THE INVENTION
`
`The present invention is directed to a method and apparatus
`for 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 manufac-
`ture of, 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, comprising:
`(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 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 ofthese spots along an optical path opposite to that
`of the incident light;
`(c) repeating steps (a) and (b) a plurality oftimes, 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; and
`(e) based on the determined spot-specific positions, gener-
`ating data representative of the topology of said portion.
`By a further ofits aspects, the present invention provides an
`apparatus for determining surface topology of a portion of a
`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;
`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 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 measur-
`ing intensity of each of a plurality of light beams retum-
`
`

`

`US 8,638,447 B2
`
`3
`ing from said spots propagating through an optical path
`opposite to that of the incident light beams;
`a processor coupled to said detector for determining for
`each light beam a spot-specific position, being the posi-
`tion 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.
`The probing member, the illumination unit and the focus-
`ing 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 deter-
`
`mination of the spot-specific 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 deriva-
`tive function indicates a maximum maximum intensity. The
`term “spot-specific position (SSP)” will be used to denote the
`relative in-focus position regardless ofthe 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.
`
`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 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 ofthe focal plane is scanned over the entire range
`of depth or Z component possible for 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 indepen-
`dent 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 focus-
`ing 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 maxi-
`mum illuminated intensity was not reached, the SSP is deter-
`mined by 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 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
`examples include a crown to be fitted on a tooth stump or a
`bridge to be fitted within teeth.
`
`10
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`
`By one embodiment of the invention, the plurality of inci-
`dent light beams are produced by splitting a parent beam.
`Alternatively, each incident 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 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 emit-
`ters,
`the different
`light components differing from one
`another by at least one detectable parameter. Such a detect-
`able parameter may, for example be wavelength, phase, dif-
`ferent duration or pulse pattern, etc. 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 ofthe 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 maxi-
`mum 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 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 computer environment. The recon-
`structed 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 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 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. Typically, but
`not exclusively, the apparatus of the invention comprises a
`communication port for connection to a communication net-
`work which may be a computer network, a telephone net-
`work, a wireless communication network, etc.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`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 refer-
`ence to the accompanying drawings, in which:
`FIGS. 1A and 1B are a schematic illustration by way of a
`block diagram of an apparatus in accordance with an embodi-
`ment of the invention (FIG. 1B is a continuation of FIG. 1A);
`FIG. 2A is a top view of a probing member in accordance
`with an embodiment of the invention;
`
`

`

`US 8,638,447 B2
`
`5
`FIG. 2B is a longitudinal cross-section through line II-II in
`FIG. 2A, depicting also some exemplary rays passing there-
`through;
`FIG. 3 is a schematic illustration of another embodiment of
`
`a probing member; and
`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 origi-
`nating from a different light emitter.
`
`DETAILED DESCRIPTION OF A PREFERRED
`EMBODIMENT
`
`Reference is first being made to FIGS. 1A and 1B illustrat-
`ing, by way of a block diagram an apparatus generally des-
`ignated 20, consisting of an optical device 22 coupled to a
`processor 24. The embodiment illustrated in FIG. 1 is par-
`ticularly useful for determining the three-dimensional struc-
`ture of a teeth segment 26, particularly a teeth segment where
`at least one tooth or portion oftooth 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 three-dimensional struc-
`ture 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, in this specific embodiment,
`a semiconductor laser unit 28 emitting a laser light, as repre-
`sented by arrow 30. 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 into a plurality of
`incident light beams 36, represented here, for ease of illustra-
`tion, 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 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 measurement accuracy of the apparatus. As a
`result ofthis 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. 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 46. Elements 42, 44 and 46 are
`generally as known per se. It should however be noted that
`telecentric confocal optics avoids distance-introduced mag-
`nification changes and maintains the same magnification of
`the image over a wide range of distances in the Z direction
`
`5
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`60
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`65
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`6
`(the Z direction being the direction ofbeam propagation). The
`relay optics 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 comprises a mirror
`ofthe 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.
`Incident light beams 48 form an array of light beams
`arranged in an X-Y plane, in the Cartasian frame 50, propa-
`gating 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 different
`Oil-5Y1) locations. Thus, while a spot at one location may be in
`focus of the optical element 42, spots at other locations may
`be 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 other spots will be off peak.
`Thus, for each illuminated spot, a plurality of measurements
`of light intensity are made at different positions along the
`Z-axis and for each of such Oil, Y1.) location, typically the
`derivative of the intensity over distance (Z) will be made, the
`Z1. yielding maximum derivative, Z0, will be the in-focus
`distance. As pointed out above, where, as a result ofuse ofthe
`punctured mirror 40, the incident light forms a light disk on
`the surface when out of focus and a complete light spot only
`when in focus, the distance derivative will be larger when
`approaching in-focus position thus increasing accuracy ofthe
`measurement.
`
`The light scattered from each of the light spots includes a
`beam travelling initially in the Z axis along the opposite
`direction of the optical path traveled by the incident light
`beams. Each returned light beam 54 corresponds to one ofthe
`incident light beams 36. Given the unsymmetrical properties
`of mirror 40, the returned light beams are reflected in the
`direction of the detection optics generally designated 60. The
`detection optics comprises a polarizer 62 that has a plane of
`preferred polarization oriented normal to the plane polariza-
`tion ofpolarizer 32. The retumedpolarized light beam 54 pass
`through an imaging optic 64, typically a lens or a plurality of
`lenses, and then through a matrix 66 comprising an array of
`pinholes. CCD camera has a matrix or sensing elements each
`representing a pixel ofthe image and each one corresponding
`to one pinhole in the array 66.
`The CCD camera is connected to the image-capturing
`module 80 of processor unit 24. Thus, each light intensity
`measured in each ofthe sensing elements ofthe CCD camera,
`is then grabbed and analyzed, in a manner to be described
`below, by processor 24.
`Unit 22 further comprises a control module 70 connected
`to a controlling operation of both semi-conducting laser 28
`and a motor 72. Motor 72 is linked to telecentric confocal
`
`optics 42 for changing the relative location of the focal plane
`of the optics 42 along the Z-axis. In a single sequence of
`operation, control unit 70 induces motor 72 to displace the
`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 laser 28 to generate a light
`pulse. At the same time it will synchronize image-capturing
`module 80 to grab data representative of the light intensity
`from each of the sensing elements. Then in subsequent
`
`

`

`US 8,638,447 B2
`
`7
`sequences the focal plane will change in the same manner and
`the data capturing will continue over a wide focal range of
`optics 44, 44.
`Image capturing module 80 is connected to a CPU 82
`which then 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 focus, the measured
`intensity will be maximal. Thus, by determining the Z1, cor-
`responding to the maximal light intensity or by determining
`the maximum displacement derivative of the light intensity,
`for eachpixel, the relative position ofeach light spot along the
`Z axis can be determined. Thus, data representative of the
`three-dimensional pattern of a surface in the teeth segment,
`can be obtained. This three-dimensional representation may
`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 (typically a computer keyboard). In
`addition, the data representative of the surface topology may
`be transmitted through an appropriate data port, e. g. a modem
`88, through any communication network, e.g. telephone line
`90, to 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 locations around the structure, e.g. in the case of a
`teeth segment from the buccal direction, from the lingal direc-
`tion 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-dimensional structure in a computerized environment
`or a physical 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 portion of a tooth, and the image can
`then be used for the design and subsequent manufacture of a
`crown or any other prosthesis to be fitted into this segment.
`Reference is now being made to FIGS. 2A AND 2B illus-
`trating a probing member 90 in accordance with one, cur-
`rently preferred, embodiment of the invention. The probing
`member 90 is made of a light transmissive material, typically
`glass and is composed of an anterior segment 91 and a pos-
`terior segment 92, tightly glued together in an optically trans-
`missive manner at 93. Slanted face 94 is covered by a totally
`reflective mirror layer 95. Glass disk 96 defining a sensing
`surface 97 is disposed at the bottom in a manner leaving an air
`gap 98. The disk is fixed in position by a holding structure
`which is not shown. Three light rays are 99 are represented
`schematically. As can be seen, they bounce at the walls 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 sensing face 97. The light rays focus on
`focusing plane 100, the position of which can be changed by
`the focusing optics (not shown in this figure).
`Reference is now being made to FIG. 3, which is a sche-
`matic illustration of an endoscopic probe in accordance with
`an embodiment of the invention. The endoscopic probe, gen-
`erally designated 101, has a stem 102 defining a light trans-
`mission path (e.g., containing a void elongated space, being
`m