# Patent

## Title
Methods for determining optical properties with measurements having different average optical depths or thickness sensitivities

## Abstract

Optical properties of an object are determined via light provided to the object via a probe tip including a plurality of light source/light receiver pairs. Light is received from a first light source/light receiver pair, and the first light source/light receiver pair is arranged so that a first measurement generates data based on light from the object received from a first average optical depth or first thickness sensitivity. Light is received from a second light source/light receiver pair, and the second light source/light receiver pair is arranged so that a second measurement generates data based on light from the object received from a second average optical depth or a second thickness sensitivity. The second average optical depth is different from the first average optical depth. Optical properties of the object are determined based on the data generated by the first and second measurements.

## Background
This application is a continuation of application Ser. No. 10/081,879, filed Feb. 21, 2002, now U.S. Pat. No. 6,903,813.


FIELD OF THE INVENTION
The present invention relates to devices and methods for measuring optical characteristics such as color spectrums, translucence, gloss, and other characteristics of objects such as teeth, and more particularly to devices and methods for measuring the color and other optical characteristics of teeth, fabric or numerous other objects, materials or surfaces.
BACKGROUND OF THE INVENTION
A need has been recognized for devices and methods of measuring the color or other optical characteristics of teeth and other objects, particularly in the field of dentistry. Reference is made to the following applications, all by inventors hereof, which are hereby incorporated by reference, which disclose various systems and methods for measuring teeth and other objects: U.S. application Ser. No. 09/091,208, filed on Jun. 8, 1998, which is based on International Application No. PCT/US97/00126, filed on Jan. 2, 1997, which is a continuation in part of U.S. application Ser. No. 08/581,851, now U.S. Pat. No. 5,745,229, issued Apr. 28, 1998, for Apparatus and Method for Measuring Optical Characteristics of an Object; U.S. application Ser. No. 09/091,170, filed on Jun. 8, 1998, which is based on International Application No. PCT/US97/00129, filed on Jan. 2, 1997, which is a continuation in part of U.S. application Ser. No. 08/582,054, now U.S. Pat. No. 5,759,030 issued Jun. 2, 1998, for Apparatus and Method for Measuring Optical Characteristics of Teeth; PCT Application No. PCT/US98/13764, filed on Jun. 30, 1998, which is a continuation in part of U.S. application Ser. No. 08/886,223, filed on Jul. 1, 1997, for Apparatus and Method for Measuring Optical Characteristics of an Object; PCT Application No. PCT/US98/13765, filed on Jun. 30, 1998, which is a continuation in part of U.S. application Ser. No. 08/886,564, filed on Jun. 30, 1998, for Apparatus and Method for Measuring Optical Characteristics of Teeth; and U.S. application Ser. No. 08/886,566, filed on Jul. 1, 1997, for Method and Apparatus for Detecting and Preventing Counterfeiting. The foregoing patent documents are sometimes referenced collectively herein as the “Referenced Patent Documents.”
The foregoing patent documents disclose a variety of systems and methods for measuring teeth and other objects. For example, FIG. 1 of U.S. Pat. No. 5,880,826 discloses a system that uses a pen-like probe that could be held much like a pencil with the probe tip directed to the tooth or other object. FIG. 35 of U.S. Pat. No. 5,880,826 discloses a handheld configuration which may be held much like a gun, with a switch located in a position for the “trigger function” to activate the system. One color measuring system introduced to the market has a physical configuration in which the user holds the instrument “football style” (the user's hand cradles the instrument much like a user would hold a football in a traditional football throwing motion). In general, in the field of dentistry a variety of stylus, probe, gun-like and other implements have been proposed and/or utilized to varying degrees of commercial acceptance.
Although the systems described in the Referenced Patent Documents, and the above mentioned dental implements, provide a variety of physical arrangements for dental instruments, there is still a need, particularly with respect to instruments that are capable of quantifying the optical properties of dental objects such as teeth, for instruments that are easier to hold and utilize in the dental or similar environment as compared with such existing physical arrangements. In particular, there is a need for instruments of improved physical construction so that dentists and other users may measure teeth and other objects comfortably and precision, and preferably without bending or contorting the wrist, hand or other body parts.
There also continues to be a need for such instruments with improved infection prevention implements, and for such instruments that utilize multiple spectrometers to more optimally measure and quantify the optical properties of translucent, pearlescent or other optically complex materials.
SUMMARY OF THE INVENTION
The present invention provides a new and improved physical arrangement, particularly for a spectrometer or spectrophotometer-based instrument, that facilitates the measurement of optical properties of teeth and other dental and other objects and materials.
In accordance with the present invention, a housing encloses a spectrometer or spectrophotometer; preferably multiple spectrometers are utilized in order to measure multiple spectrums (preferably simultaneously) of light received from the object under test. The housing includes a body portion that preferably houses the spectrometer(s) or spectrophotometer(s) (herein, a spectrophotometer generally consists of a spectrometer and light source, and perhaps a power source such as a battery). The spectrometer assembly preferably is located in the palm of the user's hand. Extending from, and preferably integral with, the body portion is neck portion. Extending from, and preferably integral with, the neck portion is a tip portion. Optics, such as light guiding fiber optics or the like, preferably carry light to a probe tip at an end of the portion, at which point the light leaves the instrument in order to illuminate the tooth or other object or material, and return the light to the spectrometer(s) for analysis.
In accordance with preferred embodiments, the neck portion is configured to have an upper portion that includes a location for placement of a user's index finger. This location may have an indenture or other textured area or friction surface (such as small bumps, a rubber surface or the like that tends to increase the friction between the user's index finger and the instrument) such that a user's index finger may be securably be positioned at that location. With the user's index finger reliably positioned at such a location on the neck portion, the tip portion of the instrument may be more precisely moved towards a desired or predetermined location on the tooth or other object so that the tip may measure the desired or predetermined location.
Also in accordance with preferred embodiments, one or a plurality of switches are provided for activation and/or control of the instrument, preferably located and operated in a manner such that the measurement is not adversely affected by undesired movement induced by the switch activation. One or more switches may be located in a position where an index finger is positioned during use of the instrument. Alternatively, one or more switches may be located on a lower surface of the body portion such that the switch may be activated by a squeezing motion of one or more of the user's fingers, while not pulling the instrument away from the desired or predetermined location on the tooth or other object. In addition (or alternatively), the tip may move respect to other parts of the tip portion or the neck and body portion such that the movement of the tip may be detected electrically, mechanically or optically.
An improved barrier infection control implement also is preferably utilized in accordance with the present invention. Preferably, a pliant, stretchy, transparent material fully encases and covers the tip portion of the instrument. In preferred embodiments, an inner surface of the infection control implement is relatively smooth or “satinized” in order to facilitate guiding the tip portion of the instrument into the infection control implement, and an outer surface of the infection control implement has a degree of tackiness or stickiness, particularly as compared to the inner surface, such that upon contact with the object under evaluation the tip portion mildly adheres to the surface of the object. With such an outer surface, measurement of objects such as teeth are facilitated, as the tip of the instrument may be directed to a desired spot of the object for evaluation, with the stickiness, or “non-slippery-ness,” of the outer surface of the infection control implement serving to prevent movement of the tip from the desired spot on the object. Preferably, a calibration measurement of a material of known or predetermined optical characteristics serve to calibrate out any optical effect introduced by the infection control implement. Such a calibration measurement preferably is conducted at instrument powerup, prior to taking actual measurements, at periodic or other suitable intervals. Such a calibration measurement also serves to normalize the instrument and calibrate out effects due to lamp drift, aging of fiber optics, optical couplers, filters and other optical components and the like, as well as to normalize the electronics and produce a “black level,” such as described in the previously referenced patent documents.
Accordingly, it is an object of the present invention to provide an improved spectrometer/spectrophotometer, and/or housing arrangement for a spectrometer or spectrophotometer, particularly for the field of dentistry.
It is another object of the present invention to provide an improved spectrometer/spectrophotometer, and/or housing arrangement for a spectrometer or spectrophotometer, particularly having a body portion that encloses the spectrometer or spectrometer and fits in the user's hand during operation of the instrument.
It is yet another object of the present invention to provide an improved spectrometer/spectrophotometer, and/or housing arrangement for a spectrometer or spectrophotometer, particularly having a neck portion with an index finger placement location.
It is still another object of the present invention having one or more switches that activate or control the instrument and are arranged, such as with a moveable tip, located on an under side of the body portion, such that the one or more switches may be operated while not having the act of activating the switch induce undesired movement of the instrument.
It is yet another object of the present invention to provide an improved instrument for, and methods of making, optical measurements utilizing a plurality of spectrometers or other color measuring devices in order to quantify optical properties of materials that may be translucent, pearlescent or otherwise optically complex; particular example being human teeth and restorative dental materials, gems, multi-layered painted articles and the like.
Finally, it is an object of the present invention to provide such an instrument that may be utilized with a barrier infection or contamination control implement, which preferably has a smooth inner surface and a slip-resistant outer surface, the inner surface of which preferably serves to facilitate insertion of the instrument's probe tip into the infection or contamination control implement, and the outer surface of which preferably facilitates measurement of the object under evaluation by providing a probe tip surface that tends not to slip during from the desired measurement spot during the optical measurement.



BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and other advantages of the present invention will become more apparent by describing in detail the preferred embodiments of the present invention with reference to the attached drawings in which:
FIG. 1 is an overview of a spectrometer/spectrophotometer housing arrangement in accordance with an exemplary preferred embodiment of the present invention;
FIG. 2 is an interior view of a spectrometer/spectrophotometer housing arrangement in accordance with an exemplary preferred embodiment of the present invention;
FIG. 3 is an illustration of a user utilizing a spectrometer/spectrophotometer arrangement in accordance with an exemplary preferred embodiment of the present invention;
FIGS. 4, 5A–5D and 6 illustrate exemplary probe, optical and spectrometer configuration for an exemplary preferred multi-spectrometer embodiment of the present invention;
FIGS. 7A–7D illustrate an improved infection/contamination prevention implement (and its manufacture) utilized in certain preferred embodiments of the present invention;
FIG. 8 illustrates an exemplary base unit and calibration block in accordance with an exemplary preferred embodiment of the present invention;
FIGS. 9A–9G illustrate exemplary display screens that may be utilized in accordance with the present invention; and
FIG. 10 illustrates an exemplary multi-camera image display, with superimposed shade data, in accordance with an exemplary alternative preferred embodiment of the present invention.



DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described in greater detail with reference to certain preferred and alternative embodiments. As described below, refinements and substitutions of the various embodiments are possible based on the principles and teachings herein.
FIG. 1 is an overview of a spectrometer/spectrophotometer housing arrangement in accordance with an exemplary preferred embodiment of the present invention. As illustrated, spectrometer/spectrophotometer 1 in accordance with preferred embodiments preferably includes a housing includes body portion 6A and 6B that preferably houses the spectrometer or spectrophotometer (herein, the spectrophotometer generally consisting of a spectrometer and light source, and perhaps a power source such as a battery, while a spectrometer embodiment may provide light that is provided via an optical cable from an external light source). In the illustrated embodiment, the body portion 6A/6B consists of two parts, upper portion 6A and lower portion 6B, the two portions of which together define the body portion, and in the preferred embodiment the neck portion. Such a two or multi-part construction facilitates manufacture of the unit, as the upper portion may be removed, and the interior components such as the spectrometer may then be more readily installed or assembled in the interior of the housing, etc.
In operation, the spectrometer assembly within body portion 6A/6B preferably is located in the palm of the user's hand, thus enabling the spectrometer assembly to be positioned close to the object under test, and preferably so that no optical fibers or the like that serve to couple light from the object under test to the spectrometer assembly will be bent or kinked by user of the instrument (the adverse affects, such as optical transmission changes, from bending or kinking optical fibers are described in greater detail in the Referenced Patent Documents). Extending from, and preferably integral with, body portion 6A/6B is neck portion 8 (in the illustrated embodiment, neck portion 8 is formed from the upper and lower portions 6A and 6B of the body portion, although the present invention is not necessarily limited to this construction. With neck portion 8 also consisting of upper and lower portions, the upper portion may be removed such as to facilitate assembly, such as positioning of fiber optics or light guiding members, etc., into the tip, etc. Preferably, the neck portion extends in a curved manner in a direction away from the body portion and toward the tip and the person whose tooth is to be measured (as more fully described elsewhere herein). As will be appreciated, the neck portion may extend in a direction and length so as to facilitate measurement of the target object, such as a tooth in a patient's mouth.
Extending from, and preferably integral with, neck portion 8 is tip portion 10. Optics, such as light guiding fiber optics or the like, preferably carry light to tip end 12 at end of tip portion 10, at which point the light leaves the instrument in order to illuminate the tooth or other object or material, and return the light to the spectrometer for analysis. With such a probe configuration, with neck portion 8 and tip portion 10 configured such as illustrated, the instrument may more readily extend into the mouth of a patient and serve to facilitate the measurement of teeth and the like. Preferably, neck portion 8 and tip portion 10 together may serve as a form of cheek retractor, or have a length and shape, so as to enable measurement of posterior or inside/back teeth of a patient, as opposed to other techniques in which only anterior or front teeth may be measured. While the illustrated shape of FIG. 1 is exemplary, what should be appreciated is that body portion 6A/6B may house the spectrometer/spectrometer, while neck portion 8 and tip portion 10 extend away from body portion 6A/6B and carry source and receiver fiber optics or light guides to end 12 of tip portion 10, with neck portion 8 and tip portion 10 collectively having a length and/or shape to facilitate the measurement of desired samples, such as teeth, which may be located in difficult to reach places (such as posterior teeth in the mouth of a patient).
In accordance with preferred embodiments, the neck portion is configured to have an upper portion that includes a location (such as location 4, as illustrated in FIG. 1) for placement of a user's index finger. This location may have an indented portion or other textured area or friction surface (such as small bumps, a rubber surface or the like that tends to increase the friction between the user's index finger and the instrument) such that a user's index finger may be securably be positioned at that location. With the user's index finger reliably positioned at such a location on the neck portion, the tip portion of the instrument may be more precisely moved towards a desired or predetermined location on the tooth or other object so that the tip may measure the desired or predetermined location.
Also in accordance with preferred embodiments, one or a plurality of switches are provided for activation and/or control of the instrument, preferably located and operated in a manner such that the measurement is not adversely affected by undesired movement induced by the switch activation. One or more switches may be located on a lower surface of the body portion such that the switch may be activated by a squeezing motion of one or more of the user's fingers, while not pulling the instrument away from the desired or predetermined location on the tooth or other object. In addition (or alternatively), the tip may move respect to other parts of the tip portion or the neck and body portion such that the movement of the tip may be detected electrically, mechanically or optically. In one exemplary preferred embodiment, a membrane or spring activated-type switch is positioned within location 4, such that a movement of the user's index finger causes activation of the switch, which may be detected such as to initiate a measurement (which may be a measurement of the object under test, a calibration or normalization reference or standard, etc.). What is important is that body portion 6A/6B include an intuitive and nature placement for position of one or more of the operator's fingers, preferably in a manner that naturally and intuitively guides the probe tip towards a desired area for measurement, with a switch that may be activated with a slight and natural movement that does not tend to cause undesired motion of the probe tip from the desired area for measurement (as described in the Referenced Patent Documents, for example, movement away from such a desired area or at an undesired angle, etc., may be detected or quantified, with optical measurements either adjusted or rejected based on the movement or amount of movement, etc.).
FIG. 2 is an interior view of a spectrometer/spectrophotometer housing arrangement in accordance with an exemplary preferred embodiment of the present invention. FIG. 2 illustrates in greater detail general aspects of such an exemplary preferred embodiment, which other figures will illustrate preferred optical and spectrometer configurations, etc., that may be used with such exemplary arrangements as are illustrated in FIG. 2.
Generally, implementations of such embodiments constitute spectrophotometers, which generally consist of a light source (e.g., light source 14) that provides light to the object under test (e.g., such as via light source member 16, which may constitute a fiber optic or fiber optic assembly). Light is returned from the object and received and carried (e.g., such as via light receiver member 18, which may constitute a fiber optic or fiber optic assembly or multiple fiber optics, as in preferred embodiments to be described hereinafter) to spectrometer assembly 20 for analysis. In accordance with preferred embodiments of the present invention, however, spectrometer 20 is positioned inside of body portion 6A/6B so that the bulk of spectrometer assembly 20 is effectively positioned inside the operator's hand, with neck portion 8 and tip portion 10 extending away from body portion 6A/6B in a manner to facilitate measurement of objects such as teeth, which may be inconveniently located, such as inside of a person's mouth.
As will be appreciated from FIG. 2, light source 14 may be located within or integral with body portion 6A/6B, and a suitable power source (such as battery 15 via power conductors 15A) may provide power for light source 14 and the electronics of spectrometer assembly 20. In such embodiments, the underside of body portion 6A/6B may carry a display device (such as generally illustrated by display device 6C in FIG. 1) that outputs data indicative of the optical characteristics of the object being measured (such as, as discussed in detail in the Referenced Patent Documents). This may be, for example, an output of a closest color or shade match (or closest match), such as a Pantone or Vita shade guide value, a paint or other pigment specifier or formulation, pass/fail indication, etc. Also as will be appreciated, spectrometer 20 may include a processing device (again, such as discussed in detail in the Referenced Patent Documents), which may include memory, input/output circuitry and the like, such that data generated by spectrometer assembly 20 may not only be used for color or shade prediction, but be displayed or transferred to another computer device as spectral or other data. Such data transfer from the handheld device may be by customer or standard serial or parallel interface, USB, etc., or may be wireless, such as using a wireless transceiver arrangement such as based on what are known as the Bluetooth or 802.11 or other wireless protocol, or may be a docking station-type data transmission (i.e., data is collected and locally stored within spectrometer assembly 20 or elsewhere within body portion 6A/6B, and subsequently transmitted via a wired or wireless connection by positioning body portion 6A/6B within a docking station or cradle, with electrical connectors for data transmission or battery recharging, etc., on body portion 6A/6B mating with corresponding electrical connectors on the docking station or cradle, etc.). What is important is that the handheld device include one or multiple spectrometers such as illustrated by spectrometer assembly 20, which spectrally analyze light returned from the object under test, with the data generated by the spectral analysis further processed, either with processing circuitry within spectrometer assembly 20 (or elsewhere within or integral to body portion 6A/6B, etc.) or external thereto, such as by a wired or wireless data connection to an external computer/processing device, which may further process the data, such as for shade or color or pigment prediction, display or color or spectral data, data storage, transmission to remote locations for processing or display or for production of articles based on data generated by spectrometer assembly 20, etc. Such exemplary uses of data generated by spectrometer assembly 20 are discussed in greater detail in the Referenced Patent Documents.
In a similar manner, the light provided to the object under may be generated by a light source integral to body portion 6A/6B (such as via light source 14), or may be generated by a light that is not integral to body portion 6A/6B but is instead generated external to body portion 6A/6B and provided to body portion 6A/6B via an optical cable (such as a light source fiber optic). In one such embodiment, an external unit provides light to body portion 6A/6B via a fiber optic cable or cable assembly (e.g., collection of fiber optics), with data and/or power cables being provided along with the fiber optic cable/cable assembly from the external unit. With such embodiments, the external unit may include a power supply, light source, display and associated electronics/processing, such that body portion 6A/6B includes fiber optics to provide light to and from the object under test, with spectrometer assembly 20 generating spectral data, which may then be transferred to a processor in the external unit via the data cables. As will be appreciated, the light source optic cable/cable assembly and the data and/or power cables may be provided, for example, in a single monocoil, such as may be constructed with stainless steel, aluminum or other material known in the art. Such exemplary arrangements will be explained in greater detail hereinafter.
FIG. 3 is an illustration of a user utilizing a spectrometer/spectrophotometer arrangement in accordance with an exemplary preferred embodiment of the present invention. As illustrated in FIG. 3, hand 21 of a user or operator may grasp body portion 6A/6B such as by wrapping of fingers around body portion 6A/6B, preferably with index (or other) finger 21A being positioned in an extended or semi-extended manner (such as is illustrated) with finger tip 21B being positioned within or on a physical placement feature on neck portion 8 (see, e.g., location 4 discussed in connection with FIG. 1). A switch for initiation of a measurement, for example, may be located under finger tip 21B or under finger tip(s) 21C (such as previously described).
What is important to note from FIG. 3 is that spectrometer assembly 20, within body portion 6A/6B is positioned generally within the volume created by hand 21 holding body portion 6A/6B, preferably with a natural and physically intuitive position for the index and other fingers of the user/operator, and preferably with a suitable membrane, spring or other switch located and configured in a manner that it may be activated by the user/operator without a significant tendency to cause movement of the tip end from the desired area for measurement on the object under test. Further, in embodiments where body portion 6A/6B is coupled to an external unit via an optical and/or electrical cable or cable assembly (such as described elsewhere herein), as illustrated in FIG. 3 cable/cable assembly 22 is positioned to exit body portion 6A/6B preferably from a rear portion of body portion 6A/6B, which tends to cause cable/cable assembly 22 to be below the arm of the user/operator as illustrated. With other instruments, a cable often times exits a probe or handpiece assembly so as to over the user's arm and/or hand and tend to pull down the user's arm and/or hand. In accordance with embodiments of the present invention, however, it has been determined that desirable spectral/optical measurements may be made with a spectrometer positioned within a handpiece as described and illustrated, with any cable/cable assembly extending from the handpiece exiting the body of the handpiece at a position to be below the arm/hand of the user, such that the weight of any such cable/cable assembly does not tend to pull the hand or arm of the user during operation, or to cause forces that would cause the user to tire more easily from use of the instrument, etc. This has been determined to be particularly true when the present invention is applied to fields such as dentistry, when a dental professional may desire to carefully target the probe tip to one or more desired areas of a tooth or teeth (such as for measuring a plurality of anterior and posterior teeth, as described elsewhere herein), with the handpiece being configured to enable the dental professional to guide the probe tip to the desired area or areas, with a switch configured to initiate measurements in a manner not to cause movement of the handpiece tip from the desired area or areas, and without any cable/cable assembly tending to pull the dental professional's arm or hand in a manner that may likewise tend to cause movement of the handpiece tip from the desired area or areas, etc. Of course, as described elsewhere herein, a cable/cable assembly extending from the handpiece is optional, and in other embodiments wireless data transmission, docking station data transmission, etc., may be utilized (and in such embodiments there may be no cable/cable assembly extending from the handpiece, etc.).
As described elsewhere herein and in the Referenced Patent Documents, in preferred embodiments spectral measurements are made with a highly miniaturized spectrometer assembly, which preferably consist of an array or other plurality of sensors (preferably consisting of light to frequency converters), with light coupled to at least certain of the sensors via filters or filter elements (which preferably are interference filters, and which may be discrete bandpass type filters, or which collectively may consist of a color gradient or linear variable type filter, etc.). Preferably, light is coupled from a light source to the object under test via one or more light sources, which may be fiber optics, and preferably light is received from the object under test and coupled to the sensors via the filters or filter elements. Embodiments of the present invention provide improvements and enhancements to concepts such as the foregoing, and enable improved systems and methods for measuring the optical properties of optically complex materials, including objects that are translucent, pearlescent, etc., and including objects such as teeth, dental restorations, gems, etc. In certain preferred embodiments, a multi-spectrometer design is utilized to provide multiple spectral-type measurements, preferably in parallel, and preferably with different source-receiver combinations that enable various complex materials to be optically measured.
Referring now to FIG. 4, an exemplary embodiment of such a multi-spectrometer design will now be described. Light from a light source (not shown in FIG. 4; preferably an incandescent lamp with generally known optical properties, such as color temperature) is provided via optical fiber 24 (e.g., which may be a 4.0 millimeter glass or other optical fiber bundle). Light from fiber 24 is coupled to fiber bundle 24A, three fibers of which (i.e., fibers 27, which may be 1.0 millimeter plastic fibers) are coupled to three sensors via filters (preferably three separate bands of predetermined wavelengths over the visible band; e.g., bandpass interference filters). Fibers 27 and the associated filters will be understood to constitute a first spectrometer or spectral measuring device, which preferably serve to track and monitor the output of the light source. As will be understood, the choice of three fibers and three bands to track the light source is exemplary; one, two, three, four or more bands could be similarly be used to track the light source, but three bands, along with some understanding of the properties of the light source, have been determined to provide a sufficient level of information regarding the light output of the lamp; as will be further understood, in the event of lamp drift, such may be detected and the sensed via fibers 27, and spectral measurements of the object under test either adjusted or rejected due to changes in the light source output, etc. In FIG. 4, elements 35 generally illustrate a ferrule coupled to the individual fibers, which may be utilized to couple the fiber to aperture plate 34, which serves to position the end of the fiber so as to couple light to filters/sensors 36 (in FIG. 4, the filters and sensors are shown as a combined item for discussion purposes; it is understood, based on the description elsewhere herein and in the Referenced Patent Documents, that the particular coupling details between the fiber ends and the sensors may be configured in a variety of ways and may include, for example, aperture plates, lenses, lens assemblies, spacers, etc.; what is important for this particular embodiment is that light from the lamp is coupled to sensors via filters in order to provide a lamp monitoring spectral sensing implement which monitors the lamp source output, etc.). Filters/sensors/electronics 40 of FIG. 4 generally refers to the filters and sensors, and associated electronics for reading the outputs of the individual sensors, for implementing multiple spectrometers and topology angle sensors, more details of which may be understood from the Referenced Patent Documents.
Fibers 24B from fiber bundle 24A are provided to probe tip 26 as illustrated. In the illustrated embodiment, fibers 24B constitute 12 fibers, which may consist of 1.0 millimeter plastic fibers. The arrangement of fibers 24B in probe tip 26, which serve to provide a plurality of light sources, or effectively a ring of light, are illustrated in FIG. 6 and will be described in greater detail hereinafter.
Light returned from the object under test is received by probe tip 26 via a plurality of light receivers. Such light receivers preferably may consist of a center light receiver 30, preferably a 1 millimeter plastic fiber, and also a first set (preferably three) of light receivers 33 not from the center of the probe tip and a second set (preferably three) of light receivers 28 also not from the center of the probe tip.
Center light receiver 30 is preferably coupled to a plurality of sensors via a plurality of filters, with the filters preferably providing bandpass filters spaced over the spectral band(s) of interference; for example, the filters may have bandpass characteristics such that the filters collectively span the visible band, such as described in the Referenced Patent Documents. In a preferred embodiment, center light receiver 30 is coupled to randomized fiber optic 31, which preferably has and input that receives light via light receiver 30 via optical coupler/splitter 30A (which may include a lens to collimate light from light receiver 30 to more optimally couple the light provided to randomized fiber optic 31), and has twelve outputs, each of which provides light that is coupled to a sensor through one of the filters. As described in the Referenced Patent Documents, the use of a such a randomized implement may help serve to destroy any angular or similar dependencies of the light received by light receiver 30, with the light provided to the twelve outputs being more or less equal or having reduced dependency as to where on light receiver 30 is the received light receiver (and at what angle, etc.) over the twelve outputs. Preferably, randomized fiber optic 31 is an optical implement which constitutes a large number of preferably glass fibers, with an input area that is randomly divided and apportioned to N (preferably 12) output areas, which in the illustrated embodiment constitute 12 fiber optic bundles each of which couples light to a sensor via a filter. As also described in the Referenced Patent Documents, such a randomized implement efficiently provides light to the filter/sensor combinations with less angular dependencies, etc. The N (preferably 12) outputs of randomized fiber optic 31, and the associated filter/sensors, preferably provide a first spectrometer/spectral sensing implement for generating spectral data based on the light received from the object under test.
Light receivers 28 preferably are coupled to sensors via filters in order to provide a second spectrometer/spectral sensing implement for generating spectral data based on the light received from the object under test. In the illustrated embodiment, light receivers 28 constitute three fiber optics. While three fiber optics may be coupled to filters/sensors and provide a three band spectral sensing device, in the illustrated embodiment six spectral bands are utilized for the second spectrometer/spectral sensing device. In the illustrated embodiment, the three fibers of light receivers 28 are coupled to light pipe 29 (which may be a 2 millimeter plastic light pipe), which serves to couple and mix and diffuse light from (preferably) three input fibers 28 to (preferably) six output fibers 32. The preferably six output fibers are coupled to filters/sensors as illustrated. The preferably 6 output fibers, and the associated filter/sensors, preferably provide a second spectrometer/spectral sensing implement for generating spectral data based on the light received from the object under test.
Light receivers 33 typically are coupled to sensors via neutral density filters (or no filters) and are preferably used to provide topology sensors (see, e.g., the discussion in the Referenced Patent Documents). In yet other alternative embodiments, light receivers 33 could be provided to sensors without filters, could be provided to sensors via fine bandpass filters and look at only particular spectral lines (for example, in order to detect the presence of specific materials that reflect or emit light in such particular spectral bands, etc.). In preferred embodiments, however, such light receivers 33 serve to provide positional or topology information (e.g., angle of the probe with respect to the surface of the object under test), such as described in the Referenced Patent Documents.
FIGS. 5A–5D illustrate exemplary routing and mapping of fibers in such embodiments. As will be understood from FIGS. 5A–5D, the sensors and filters and fiber optic inputs to the assembly 40 are in two rows; as FIGS. 5A–5D provide only a top view, only the top row is shown. In the illustrated embodiment, a bottom row also exists, and thus 24 total sensors are provided in the illustrated embodiment. Of course, as will be understood to those of skill in the art, the particular number of filters and sensors may be readily adapted to the particular application, and the present invention is not limited to the particular numbers in the illustrated embodiments.
In FIG. 5A, center light receiver 30 extends from probe tip 26 to coupler 30A, which preferably includes lens 30B, which serves to collect and collimate light from light receiver 30 and couple the light to the input area of randomized fiber optic 31, which serves to randomize and split the light into separate outputs, as previously described. The outputs of the randomized fiber optic 31 are coupled to filters/sensors/electronics 40 to provide a first spectrometer/spectral sensing implement, as previously described.
In FIG. 5B, light source fiber bundle 24 is coupled to coupler 25. Fibers 27 of fiber bundle 24A are coupled to filters/sensors/electronics 40 for purposes of monitoring and tracking the light source, as previously described. Fibers of fiber bundle 24B are provided to probe tip 26 and provide a plurality of light sources, also as previously described.
In FIG. 5C, light receivers 33, which preferably are inner ring fibers (see FIG. 6), extend from probe tip 26 and are coupled to filters/sensors/electronics 40 for purposes of, for example, providing topology or angle sensors, such as previously described. Also illustrated in FIG. 5C are bias lamp 41, power wires 42 and light conductor 43. As described in greater detail in the Referenced Patent Documents, in preferred embodiments bias light is provided to the sensors, which guarantee a minimal amount of light to the sensors (as will be understood from the Referenced Patent Documents, light from bias lamp 41 is not light that is provided to and returned from the object under test, but instead is a preferably separate light source that serves to bias the light sensors). Under power provided by wires 42 (with the power preferably obtained from the power supply providing power to the sensors, for example), bias lamp 41 generates bias light, which is controllably conducted to the sensors via light conductor 43.
In FIG. 5D, light receivers 28, which also are preferably inner ring fibers (see FIG. 6), extend from probe tip 26 and are coupled to light pipe or coupler 29, which serves to couple/mix/diffuse light from light receivers 28 to fibers 32. The outputs of the fibers 32 are coupled to filters/sensors/electronics 40 to provide a second spectrometer/spectral sensing implement, as previously described.
FIG. 6 illustrates an exemplary end view of probe tip 26. Center light receiver 45D is positioned generally at the center of probe tip 26. As will be understood, center light receiver generally may be considered the end of light receiver (fiber) 30, which is coupled to a first spectrometer/spectral sensing implement. A first ring is provided around center light receiver 45. In the first ring are arranged light receivers 45C and 45B, which generally may be considered the ends of light receivers 28 and 33, respectively. Light receivers 45C (preferably 3) provide light that is ultimately coupled to a second spectrometer/spectral sensing implement. Light receivers 45B (preferably 3) provide light that is coupled to sensors such as for purposes of sensing topology or angle. A plurality of light sources 45A preferably are provided in a circular arrangement in probe tip 26 (12 being illustrated in this exemplary embodiment). The plurality of light sources 45A generally constitute the ends of the fibers of fiber bundle 24B, as will be understood from the description elsewhere herein. The plurality of light sources 45A generally constitute a ring light source in probe tip 26.
Based on the foregoing, it will be understood that an instrument may be provided that utilizes multiple spectrometers in parallel, including multiple spectrometers that may serve to make spectral measurements, preferably in parallel, of the object under test. As described in greater detail in the Referenced Patent Documents, the numerical aperture, diameters and spacing of the light sources and receivers define a “critical height” below which light that is reflected from the surface of the object under test cannot be received and propagated by the light receivers. Measurements below the critical height thus are generally not dependent upon surface characteristics, as light reflected from the surface is not going to be received by the light receivers and thus sensed by the spectrometers. Light that enters the light receivers generally is light that enters the bulk of the material of the object, is scattered and displaced so that it can exit the material at a position and angle to be received and propagated by the light receivers (see the Referenced Patent Documents for a more detailed discussion of this phenomenon). Consider probe tip 26 being in contact with the surface of the object under test. In such a condition, the various source/receiver combinations provided by probe tip 26 each will be below the critical height. While conventional approaches tend to characterize optical properties that include surface reflected light (and thus tend to be more sensitive to surface irregularities, angle, etc.), it has been discovered that optically more complex objects such as teeth, which are highly translucent, may be more optimally quantified with such below the critical height measurements. With the multi-spectrometer approach of the present invention, multiple spectrometers may make multiple below the critical height measurements in parallel, and thus provide substantial optical data from which optical characteristics of the object under test (such as a shade or color prediction) may be determined.
Without being bound by theory, a discussion of certain benefits and principles of the foregoing approach will now be described. As will be appreciated from FIG. 6, center light receiver 45D is generally equi-distant from the various light sources 45A. Thus, light that is received by light receiver 45D generally is light from light sources 45A that enters the object under test, penetrates some optical depth, gets scattered, displaced, etc., and is ultimately received by light receiver 45D. Generally, however, the light originates from a light source that is in essence the same distance away from the light receiver (as will be appreciated from FIG. 6, light receiver 45D is not precisely the same distance from all of the light sources 45A, but generally are about the diameter of the fibers of the inner ring away from the lights sources 45A). Each of light receivers 45C, on the other hand, is a varying distance from the various light sources 45A (i.e., some are closer to the light sources and some are farther away from the light sources). Light receivers 45C, with its varying spacings from light sources 45A, collectively receive light that may be considered to be more of an “average depth” or optical path length within the material of the object under test (again, some close and some far away). Again, without being bound by theory, it has been determined that light receivers 45C may be used to make spectral measurements that less sensitive to the thickness of the material under test, as compared to the center light receiver 45D, which has been observed to be more sensitive to thickness. In the case of materials such as teeth or dental restorations, the perceived optical characteristics may be a function of various layers constituting the materials. In attempting to characterize such complex optical materials, it has been determined that using multiple spectrometers to make multiple measurements, with varying spacings between the sources and receivers, varying average optical path lengths or effective optical depths of the measurements, etc., provide a much greater amount of information from which to make, for example, shade or color predictions.
For example, for an instrument that is used to shade match teeth or dental restorations, the material may be a tooth or a ceramic restoration. The constituent materials generally have different optical properties, and may have different layers of differing thicknesses of differing materials in order to produce colors that are perceived to be the same by viewing human observer. Having only a single spectral measurement, for example, has been determined to provide less than sufficient data for a sufficient shade or color determination or prediction.
In accordance with the present invention, the multiple spectrometers each make spectral measurements. Depending upon the type of material under examination, for example a natural tooth versus a dental restoration (and for example a denture tooth versus a porcelain-fused-to metal “PFM” crown), with the present invention different shade prediction criteria may be utilized. For example, user input may inform the instrument what type of material is under examination; alternatively, the instrument could collect data from the multiple spectrometers and predict the type of material (which could be confirmed or over-ridden by user input, etc.). In any event, after collecting spectral data, the instrument then desires to output a color or shade value. Typically, data is stored within the instrument in the form of lookup tables or the like, and measured data is compared in some form with the stored data of the various shades in order to predict and output the closest shade or color (see, e.g., the Referenced Patent Documents). In accordance with embodiments of the present invention, however, the measured data and lookup tables, or possible combinations thereof, may be more optimally utilized depending upon the type of material under test.
For example, if a natural tooth is under examination, spectral data may be collected from the first and second spectrometers. Data from the first (center receiver) spectrometer, which generally is more sensitive to thickness, may be used exclusively for shade or color prediction, or weighted more heavily in the shade prediction as compared to data from the second (ring receiver) spectrometer, which generally is less sensitive to thickness. For a PFM restoration, which could consist of thin layers (as compared to a comparable sized natural tooth), thickness dependencies could present much greater problems with attempting to perform shade matching or color prediction for PFM samples. If a PFM restoration is under examination, spectral data may be collected from the first and second spectrometers. Data from the second (ring receiver) spectrometer, which generally is less sensitive to thickness, may be used exclusively for shade or color prediction, or weighted more heavily in the shade prediction as compared to data from the first (center receiver) spectrometer, which generally is more sensitive to thickness.
As will be understood from the foregoing, depending upon the type of material under test, a different shade matching/prediction method or algorithm will be performed. In accordance with such embodiments of the present invention, a first type of material under test (e.g., a natural tooth) would utilize a first shade matching algorithm (e.g., weigh data from the first spectrometer more heavily than data from the second spectrometer), and a second type of material under test (e.g., a PFM restoration) would utilize a second shade matching algorithm (e.g., weigh data from the second spectrometer more heavily than data from the first spectrometer). In addition, depending upon the type of material under test, different optical parameters could be utilized, again with different weights. For example, a prediction based on the closest “delta E” match between the stored shades or colors may be used for a first type of material under test, while a prediction that gives more (or less) weight to, for example “delta L” or “delta c” or “delta h,” may be used for second type of material (it being understood by those of skill in the art that L, c and h refer to luminance, chroma and hue of the well-know L-C-H system for representing color). Moreover, a first combination of data from the first and second spectrometers (with first weights given to the first and second spectrometers) and a first set of parameters (e.g., delta E) may be utilized for shade or color prediction for a first type of material, while a second combination of data from the first and second spectrometers (with second weights given to the first and second spectrometers) and a second set of parameters (e.g., delta L and/or delta c and/or delta h) may be utilized for shade or color prediction for a second type of material. With the present invention, multiple spectrometers, and/or multiple shade/color prediction/matching algorithms based on data from multiple spectrometers, may be utilized depending on the type of material being measured in order to more accurately predict/match shades and colors for a wide range of materials.
Other aspects of certain preferred embodiments of the present invention will now be described.
Referring now to FIGS. 7A–7D, an explanation will be provided of an improved barrier infection control implement that is preferably utilized in accordance with the present invention. As fields of application for the present include the dental and medical fields, and fields in which wet pigments or other materials could be applied (such as painting, printing), the probe used to make spectral or other optical measurements may come into contact with the object under test. In the case of dentistry, for example, contamination between patients is a serious concern. As explained in the Referenced Patent Documents, a barrier infection control implement may be utilized to present such contamination.
In accordance with the present invention, as illustrated in FIG. 7A, a preferably pliant, stretchy, transparent barrier 50 fully encases and covers tip portion 10 of instrument 1. As illustrated, barrier 50 preferably is pulled up the length of tip portion 10 and over neck portion 8, preferably utilizing tab portion 50A, such that hole 50B slips over protrusion 8A. Protrusion 8A preferably is an implement that is added to neck portion 8 (either affixed to neck portion 8 or fabricated such as with a plastic molding process as an integral part of neck 8) such that a user may pull barrier 50 over the tip and neck portions such that hole 50B secures barrier 50 to the probe tip. The user preferably pulls the barrier into position tab portion 50A of barrier 50 (tab portion 50A preferably is integrally formed as a part of barrier 50, but which could be a separate material welded to the material of barrier 50). The act of pulling the stretchy material of barrier 50 such that hole 50B is over protrusion 8A also serves to pull the material of barrier to be closely conforming to end 12 of tip portion 10. In accordance with the present invention, optical measurements are made through barrier 50, and it is desirable that barrier 50 preferably provide a thin, wrinkle-free covering over end 12. As previously explained, in accordance with certain preferred embodiments, measurements are made “below the critical height.” Thus, the material of barrier 50 is selected to have a thickness below (preferably much below) the lowest critical height of the various source/receiver combinations provided at end 12. It is further noted that the improved barrier described herein may desirably be utilized with the multi-spectrometer measurement technique described elsewhere herein, but such an improved barrier may also be utilized with the peaking measurement technique described in greater detail in the Referenced Patent Documents.
FIG. 7A also illustrates an improved switch/barrier control combination that is used in preferred embodiments of the present invention. As previously described elsewhere herein and in the Referenced Patent Documents, a user may initiate a calibration or measurement process by activation of a switch. An improved switch 51 is illustrated in FIG. 7A. Switch 51 preferably consists of an elongated bar, which may be a integral part of the switch, or may be a cap implement positioned over a switch type switch (with the spring providing an opposing force to the user's movement to activate the switch). The elongated bar of switch 51 may have ends on the distal and proximate ends (i.e., nearest to and farthest from end 12 of tip portion 10), which, for example, may fit into an indentation formed into neck portion 8. What is important is that the switch that the user activates to initiate a measurement have an elongated form factor, so that the switch extends a length down neck portion 8, so as to accommodate a variety of hand sizes. Thus, a user with a smaller hand size may just as easily activate switch 51 (by pressing on a lower portion of switch 51) as a user with a larger hand size (by pressing on a higher portion of switch 51). Also importantly, barrier 50, when in position on the instrument and secured thereon (such as by hole 50B over protrusion 8A), extends so as to completely cover switch 51. Thus, barrier 50 not only serves to prevent contamination, but also serves to provide a moisture or other contaminant barrier to switch 51.
Referring now to FIG. 7B, another perspective of a preferred embodiment of barrier 50 and instrument 1 is provided. As illustrated, barrier 50 extends up and over tip portion 10 and neck portion 8 of instrument 1. As illustrated, hole 50B serves to secure barrier 50 by being positioned over protrusion 8A. Also as illustrated, elongated switch 51 is positioned under barrier 50, and will be activated through barrier 50 by depression of a user's (preferably) index finger.
Referring now to FIGS. 7C and 7D, other perspectives of a preferred embodiment of barrier 50 is illustrated. While other constructions are within the scope of the present invention, barrier 50 preferably consists of a unitary material, which contains a suitable combination of properties such as strength, tear-resistance, transparency, pliability, stretchiness, etc. In a preferred embodiment, barrier 50 comprises polyurethane, but also may consist of a type of rubber, latex, or other material. Barrier 50 preferably is packaged with substrate 51 as illustrated in FIG. 7D. Substrate 51 may consist of paper or other suitable material that may protect barrier 50 prior to use, and may serve to facilitate application of barrier 50 to the instrument. Much like paper backing for a bandaid or similar instrument, the user may spread the opening of the pouch of barrier 50 by pulling the paper (desirably, the paper mildly adheres to barrier 50 during such application). As the pouch opens, the user inserts the probe tip into the pouch, and, with a combination of pulling the material of the barrier up and moving the probe tip down, the materials of the barrier stretches up and over the probe tip and neck, preferably so that hole 50B and protrusion 8A serve to secure the barrier onto the instrument. As a part of this operation, substrate 51 tears away from the material of barrier 50, and substrate 51 may then be disposed of. What is important is that the material of barrier 50 be provided to the user in a manner to secure its shape and to facilitate application to the instrument. As barrier 50 is desirably disposable, so desirably is substrate 51, which is disposed off after serving its purposes as described herein.
In preferred embodiments, an inner surface of the barrier 50 is relatively smooth or “satinized” in order to facilitate guiding the tip portion of the instrument into the barrier as described above, an outer surface of barrier 50 has a degree of tackiness or stickiness, particularly as compared to the inner surface, such that upon contact with the object under evaluation the tip portion mildly adheres to the surface of the object. With such an outer surface, measurement of objects such as teeth are facilitated, as the tip of the instrument may be directed to a desired spot of the object for evaluation, with the stickiness, or “non-slippery-ness,” of the outer surface of barrier 50 serving to prevent movement of the tip from the desired spot on the object.
Preferably, barrier 50 is manufactured by cutting or otherwise forming the material to be of the desired shape, which may include punching or otherwise forming hole 50B. This preferably is performed on substrate 51, and thus the material of barrier 50 and substrate 51 desirably may be formed of the desired overall shape in a single step. Preferably, the size and shape of hole 50B corresponds to protrusion 8A in order to reliably secure barrier 50 onto the probe. The material of barrier 50, and preferably substrate 51, is then folded, preferably in an automated manner. It should be noted that the fold is asymmetric in order to form an extended tab portion 50A of barrier 50, which may be utilized to pull barrier 50 into proper position, such as previously described. In preferred embodiments, weld 50C is formed via an RF (or other radiant energy process) or thermal type process, and preferably through substrate 51. It should be noted that the weld of the material of barrier 50 does not extend the full length of the material, but extends so as to define an inner pouch of barrier 50, while providing a substantially complete seal in order to provide a suitable contamination/infection control implement. It also should be noted that end portion 50D of barrier 50 consists of a portion not having a seam across end 12 of tip portion 10. In this regard, the width of the material used to form barrier 50 has a suitable width such that, when welded to form the pouch, and when stretched into position, a relatively flat, wrinkle-free and seam-free covering is provided over end portion 12 of tip portion 10.
Other aspects of preferred embodiments of the present invention will now be described.
FIG. 8 provides an overview of an exemplary cabled implementation of a preferred embodiment of the present invention. Spectrometer/spectrophotometer or handpiece 1 (such as previously described) preferably rests in cradle 55 when not in operation. Cradle 55 preferably is secured to base unit 60 via arm 55A. On/off switch 58 preferably is utilized to turn on or off base unit 60, although in preferred embodiments, as a safety feature, base unit 60 automatically turns itself off as a function of time (with a conventional timer circuit or processor that keeps track of on or inactive time, etc.), or as a function of temperature, with a temperature sensor included in base unit 60. As in the illustrated embodiment a light source or lamp in provided in base unit 60, such implements serve to prevent the lamp from staying on for an indefinite period of time, and reduce the risks of thermal damage, fire or the like. Display 59 preferably is provided to display color measurement data, predicted shades or the like, as will be described in greater detail hereinafter.
In operation, a use preferably first applies barrier 50 (which may be considered an “infection control tip”), which is achieved by picking up handpiece 1 from its cradle and applying barrier 50, such as previously described. An exemplary screen shot of display 59, which reminds the user to apply barrier 50, and calibrate the instrument with the barrier in position, is illustrated in FIG. 9. What is important is that the user be provided a reminder, and preferably interlock, so that the instrument cannot be operated without calibration, and preferably without calibration with the barrier properly secured to the instrument. In preferred embodiments the instrument is calibrated by being positioned in cradle 55 with barrier 50 in position, and then being rotated about the axis of arm 55A so as to come into contact with calibration block 56. Guide 57 is optionally provided to more reliably guide the tip of handpiece 1 so as to land in a center portion of calibration block 56 (calibrating near an edge of calibration block 56 is undesirable, and guide 57 is provided to reduce this possibility).
Preferably, an in contrast to typically opaque calibration standards of conventional systems, calibration block 56 is a translucent or semi-transparent material, and preferably is chosen to have optical properties (such as color, translucency or the like) that is substantially in a middle portion of the range of optical properties for the particular materials that are to measured. For example, for a dental application, the optical properties of calibration block 56 preferably are an off-white shade and translucent, roughly in the middle of color and translucency values of normal human teeth. Having such a calibration block, rather than calibrating at an extreme of an optical range (such as pure white or pure black, etc.), has been determined to give more advantageous results. This has been determined to be particularly true for translucent materials such as dental objects. Without being bound by theory, it is believed that calibrating with a translucent material, for example, can help calibrate out effects of “edge loss,” which is understood to be a problem with conventional measurement techniques for translucent materials, etc.
Also in accordance with the present invention, calibration block 56 (it should be noted that calibration and normalization in this context may be generally considered synonymous) used for calibration may be removable and cleanable, such as by autoclave cleaning. Preferably, calibration block 56 is sufficiently durable, an exemplary material being porcelain, so as to be wiped clean or autoclaved repeatedly, without substantial degradation of optical properties. In certain embodiments and operative environments, where degradation of the optical properties of the calibration block may be of concern, a two step calibration/normalization process is applied. At a first point in time, a reference standard of known optical properties is measured. This “gold standard”, which may be provided with the known optical properties (which may be loaded into the instrument and stored), is measured with the instrument (the “gold standard” is then secured and stored in a manner to minimize any degradation of optical properties). Calibration block 56 is then measured. Based on the gold standard optical properties data (known/entered and measured), and based on the measurement of the calibration block, a first set of calibration/normalization data is created. During normal operation, preferably prior to each use of the instrument, the calibration block is measured again, and based on a comparison with the first set of calibration/normalization data, a second set of calibration/normalization data is created. This second set of calibration/normalization data is preferably used to adjust the data resulting from normal operational measurements. Periodically, such as after a period of months, the gold standard may be measured again, and an updated first set of calibration/normalization data is created, etc. With such a process, changing optical properties of the calibration block, which would not be expected to change rapidly, and also be calibrated out.
It also should be noted that, in accordance with the present invention, a single calibration measurement may be used even though different types of materials may need to be measured. As previously described, for example, a dental professional may desire to measure a natural tooth and a restorative material tooth on the same patient. In accordance with the present invention, a calibration measurement is performed, which is independent of the type of material being measured. Thus, even though different shade prediction algorithms or the like may be utilized to carry out the shade prediction process (as previously described), a single calibration measurement may be conducted prior to measuring both types of materials. This is important in that, after measuring either the tooth or restorative material in the patient's mouth, a contamination risk is presented if the calibration block needs to be touched again prior to measuring the second material. In accordance with the present invention, only one calibration measurement needs to be made for measuring both types of materials.
Returning again to the calibration process as part of the normal operation of the instrument, in preferred embodiments a switch internal preferably internal to base unit 60 is activated as handpiece 1 in cradle 55 is rotated in position for the tip to be positioned in the middle of calibration block 56. In such embodiments, the instrument automatically knows that it is to enter calibration mode, and thus take a calibration measurement and generate calibration data accordingly. In alternative embodiments, calibration mode is entered upon first turning on the system or before taking a measurement, and the user must start the calibration measurement by depressing the switch (such as switch 51 of FIG. 7A) on handpiece 1. This may be a dual switch mode, where a first switch activated by the rotation of cradle 55 about the axis of arm 55A indicates to the system that it is calibration mode, while the second switch (e.g., switch 51) is activated by the user when he/she has observed that the tip of the probe is positioned in a center portion of calibration block 56. In either case, in preferred embodiments, the instrument will not operate without calibration measurement having first been performed.
It also should be noted that such a calibration measurement serves to normalize the instrument and calibrate out effects due to lamp drift, aging of fiber optics, optical couplers, filters and other optical components and the like, as well as to normalize the electronics and produce a “black level,” such as described in the Referenced Patent Documents.
It also should be noted from FIG. 9A that display 59 preferably is covered by a touchscreen so that “soft switches” may be provided, which are activated by the user touching the touchscreen over an icon or displayed button. In FIG. 9A, the presets button may be activated in order for the user to put the instrument into a mode whereby system settings (such as brightness, volume, data display options, etc.) may be changed.
Referring to FIGS. 9B to 9G, additional exemplary screen displays will be described. FIG. 9B illustrates a screen display by which the user may inform the system of the type of material being measured. As previously described, in certain embodiments the operation of the system (e.g., the manner of making shade predictions, etc.), may be optimized depending on the type of material. This is accomplished by touching the touchscreen at the appropriate portion.
As illustrated in FIG. 9C, the results of a data measurement may be conveniently displayed on display 59 as illustrated. In preferred embodiments, the output, particularly for the dental application, consists primarily of a display of one or multiple shade guide values (examples of the well-known Vita Classical and 3D Master shade guides are illustrated in FIG. 9C). In such embodiments, whether one two (or other number) of closest match color or shade values is output is a user selectable feature, such as via the preset button discussed in connection with FIG. 9A). In preferred embodiments, the type of material being measured also is displayed, such as is illustrated. What is important from FIG. 9 is that, although a very sophisticated set of measurements were made as part of the process, the output may be a simple shade or color value (or values), in a form that is readily understand or useable by the particular user. For example, the display could display Pantone colors or shades, paint formulations, pass/fail results, etc.
Also in preferred embodiments, while a standard display may show an output of reduced form (such as the simple color or shade value of FIG. 9C), additional color or spectral information also may be provided. For example, a spectral plot icon is displayed (such as illustrated at the lower left corner of the screen shot of FIG. 9C), and upon touching of the icon a reflectance spectrum of the object that was measured is displayed (see, e.g., FIG. 9F for such a spectral reflectance plot, which plots relative energy as a function of wavelength). In another example, a user may touch the Vita Classical shade guide value of FIG. 9C, and the display then presents additional information, such as the deviation from the “true” color of the displayed closest match. In another example, the Vita 3D Master shade guide value of FIG. 9C may be touched, and the user then additional information regarding the measurement result relative to value, chroma and hue in the Vita 3D Master system (see, e.g., FIG. 9E). In still another example, an “L a b” icon may be displayed (such as via the icon shown at the lower right corner of FIG. 9C), and upon touching an L a b plot may be displayed (see, e.g., FIG. 9G). What is important, and what may be appreciated from the foregoing, is that the results of the color measurement/spectral analysis process be presented in a form desired by the particular user, with a point and touch operation enabling particular users to “get behind the data” and be presented with more color/spectral data, and more color/spectral data of the form that is most desired by the particular user, etc.
In certain alternative embodiments, whether the output is a single or multiple shade guide values or colors (such as the multiple shade guide system values illustrated in FIG. 9C), the closest match may be a value in one system or the other. In certain embodiments, a confidence barrier is displayed before the displayed shade guide or color values, as illustrated in FIG. 9C. In the particular illustrated example, the closest match of the 3D Master system was determined by the instrument to be a closer match than the closest match in the Vita Classical system, which is evidenced by the larger confidence bar below the displayed Vita 3D Master value. While the confidence bar display is exemplary, what is important is that, in such embodiments, a visual indicator be provided so that the operator may determine some degree of closeness of the match. With a low confidence indicator, for example, the user may then decide to get additional color data (such as previously described) to supplement the closest match value that is displayed, etc.
As described in the Referenced Patent Documents, data from spectrometer/spectrometer may be combined with an image from a camera. This can particularly be true in the context of dentistry, where often a shade assessment is a precursor to getting a restorative tooth produced. While the shade information is of particular importance to producing an aesthetically pleasing restoration, supplementing the shade information via a camera image also be useful to the dental professional or technician or other person involved in the process. With the present invention, a single or multiple areas of a tooth may be measured. Via the touch screen the user, for example, may indicated to the instrument that one or multiple areas are to be measured. Thereafter, the user may then measure the one or multiple areas of the tooth. With a camera (such as a standard digital camera), an image of the tooth or teeth may be captured. Data captured with the image may be imported into a computing system that also receives the image from the digital camera. The measured shade data may then be superimposed onto the image from the digital camera, such as is illustrated in FIG. 10. Also as illustrated in FIG. 10, two images may be combined. One image may contain multiple shade values (or single shade values), which shows at which spot on the tooth (or teeth) the measurements (or measurement) were/was made. A second image may contain no superimposed shade data. With such a multi-image, superimposed display, the person preparing the restorative tooth, for example, may see an image with real shade/color data superimposed on the area of the tooth from which the data was collected, yet may also see an image with no superimposed shade or color data.
In other embodiments, the shade or color data may be selectively superimposed or not superimposed (which may be performed with only a single image of the camera displayed, and which may be activated by mouse/click operation, pull down menus or the like). In yet other embodiments, a single or multi-image is displayed, with shade data superimposed, and with additional color or spectral data displayed (such as is illustrated in the displays of FIGS. 9E–9G) upon further command. In one example, the user may click the area of the tooth and a superimposed shade value is displayed; in a subsequent click of the shade value, additional color or spectral data is displayed. In such embodiments, for example, subsequent clicks scroll through the various shade/color/spectral data options so that the user may display the type and level of information that he/she may desire in the particular situation.
Although the invention has been described in conjunction with specific preferred and other embodiments, it is evident that many substitutions, alternatives and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, the invention is intended to embrace all of the alternatives and variations that fall within the spirit and scope of the appended claims. For example, it should be understood that, in accordance with the various alternative embodiments described herein, various systems, and uses and methods based on such systems, may be obtained. The various refinements and alternative and additional features also described may be combined to provide additional advantageous combinations and the like in accordance with the present invention. Also as will be understood by those skilled in the art based on the foregoing description, various aspects of the preferred embodiments may be used in various subcombinations to achieve at least certain of the benefits and attributes described herein, and such subcombinations also are within the scope of the present invention. All such refinements, enhancements and further uses of the present invention are within the scope of the present invention.

## Claims

1. A method for determining optical properties of an object, comprising:
providing light to the object via a probe tip including a plurality of light source/light receiver pairs;
receiving light from a first light source/light receiver pair, wherein the first light source/light receiver pair is arranged so that a first measurement generates data based on light from the object received from a first average optical depth;
receiving light from a second light source/light receiver pair, wherein the second light source/light receiver pair is arranged so that a second measurement generates data based on light from the object received from a second average optical depth, wherein the second average optical depth is different from the first average optical depth;
processing the data generated from the first and second measurements, wherein optical properties of the object are determined based on the data generated by the first and second measurements.

2. The method of claim 1, wherein the first light source/light receiver pair comprises a plurality of light sources and a single light receiver.

3. The method of claim 1, wherein the second light source/light receiver pair comprises a plurality of light sources and a single light receiver.

4. The method of claim 1, wherein one or more light source/light receiver pair is configured so that one or more light receivers do not propagate light that is specularly reflected from a surface of the object.

5. The method of claim 4, wherein the object comprises a translucent object.

6. The method of claim 1, wherein a processor determines optical properties of the object based on applying first and second factors to the data generated by the first and second measurements, respectively.

7. The method of claim 6, wherein the first and second factors vary depending upon a type of the object.

8. The method of claim 1, wherein the probe tip is coupled to a body, wherein the body encloses one or more spectrometer systems, wherein optical properties of the object are determined by positioning the probe tip in proximity of the object, wherein a user's hand substantially encompasses at least a portion of the body enclosing the one or more spectrometer systems, wherein the system comprises a handheld spectrophotometer.

9. A method for determining optical properties of an object, comprising:
providing light to the object via a probe tip including a plurality of light source/light receiver pairs;
receiving light from a first light source/light receiver pair, wherein the first light source/light receiver pair is arranged so that a first measurement generates data having a first sensitivity based on a thickness of a material of the object;
receiving light from a second light source/light receiver pair, wherein the second light source/light receiver pair is arranged so that a second measurement generates data having a second sensitivity based on a thickness of a material of the object, wherein the second sensitivity is different from the first sensitivity;
processing the data generated from the first and second measurements, wherein optical properties of the object are determined based on the data generated by the first and second measurements.

10. The method of claim 9, wherein the first light source/light receiver pair comprises a plurality of light sources and a single light receiver.

11. The method of claim 9, wherein the second light source/light receiver pair comprises a plurality of light sources and a single light receiver.

12. The method of claim 9, wherein one or more light source/light receiver pair is configured so that one or more light receivers do not propagate light that is specularly reflected from a surface of the object.

13. The method of claim 12, wherein the object comprises a translucent object.

14. The method of claim 9, wherein a processor determines optical properties of the object based on applying first and second factors to the data generated by the first and second measurements, respectively.

15. The method of claim 14, wherein the first and second factors vary depending upon a type of the object.

16. The method of claim 9, wherein the probe tip is coupled to a body, wherein the body encloses one or more spectrometer systems, wherein optical properties of the object are determined by positioning the probe tip in proximity of the object, wherein a user's hand substantially encompasses at least a portion of the body enclosing the one or more spectrometer systems, wherein the system comprises a handheld spectrophotometer.

17. A system for determining optical properties of an object, the system including a probe tip having one or more light sources and one or more light receivers, wherein the probe tip is positioned in proximity to the object, wherein the probe tip is encompassed by a removable barrier, wherein the barrier has a first, inner surface positioned adjacent the probe tip that has surface characteristics to facilitate insertion of the probe tip into the barrier, wherein the barrier has a second, outer surface that comes into contact with the object and that has surface characteristics to resist sliding of the probe tip with respect to the object when the outer surface is in contact with the object, wherein light from the one or more light sources is returned from the object through the barrier to the one or more light receivers, wherein light received by the one or more light receivers is measured by one or more spectrometer systems, wherein optical properties of the object are determined, wherein the probe tip is coupled to a body, wherein the body encloses the one or more spectrometer systems, wherein optical properties of the object are determined by positioning the probe tip in proximity of the object, wherein a user's hand substantially encompasses at least a portion of the body enclosing the one or more spectrometer systems, wherein the system comprises a handheld spectrophotometer.

18. The system of claim 17, wherein the one or more light sources and the one or more light receivers are configured so that at least one of the light receivers does not propagate light that is specularly reflected from a surface of the object.

19. The system of claim 17, wherein at least one calibration measurement of a second object of known optical properties is taken, wherein optical effects of the barrier are compensated by the calibration measurement.

20. The system of claim 17, wherein the one or more light receivers comprise a plurality of light receivers, wherein a first spectrometer system receives light from a first set of the plurality of light receivers, wherein the first spectrometer system generates data having a first sensitivity based on a thickness of a material of the object, wherein a second spectrometer system receives light from a second set of the plurality of light receivers, wherein the second spectrometer system generates data having a second sensitivity based on the thickness of a material of the object, wherein the second sensitivity is different from the first sensitivity, wherein a processor receives data generated by the first spectrometer system and the second spectrometer system, wherein optical properties of the object are determined based on data generated by the first and second spectrometer systems.