Background of the Invention : The prior art discloses a number of devices utilizing polarized light for surface irradiation and reflectance inspection. For example, U. S. Patent No. 2, 120, 365 to Kriebel discloses the use of polarizing lenses in eye-glasses for orthogonally polarizing light being viewed. The light originates from a source located on the side of an object or material of interest opposite to the viewer which allows for examining the photo-elastic effects of the light bending around the object.

Another reference, U. S. Patent No. 2, 947, 212 to Woods shows detection of surface conditions of sheet metal by irradiating a surface with polarized light and using a polarizer in the optical path of the detector. This allows for only the viewing of the polarized light while eliminating all extraneous light rays. Similarly, U. S. Patent No. 3, 904, 293 to Gee uses linearly polarized light to irradiate a surface and then detects the reflected light. Prior to the reflected light being detected, it must first pass through a polarizing beam splitter which separates the light into its principal polarized (incident) and orthogonally polarized (depolarized) wave components. These two distinct waves are then detected by different detectors and changes in the surface texture will cause corresponding changes in the detected signal characteristics to be compared.

U. S. Patent No. 5, 053, 704 to Fitzpatrick is for imaging a surface to detect cracks, flaws, voids, and the like. To do this, a magneto-optical substrate including a conductive sheet is laid over the target material. A current is passed through the conductive sheet to provide a biased magnetic field. Polarized light is then directed through the substrate onto the target material and the reflected light is viewed through a separate linear polarizer. As the plane of the incident polarized light is rotated, in the scalar product of the wave vector due to the biased magnetic field.

Further, U. S. Patent No. 5, 198, 875 to Bazin et al also teaches irradiation of a surface with polarized light. Bazin et al sets up two detectors, one at an angle of reflectance equal to the angle of incidence while another detector is located perpendicularly to the surface. The reflected polarized light is passed through polarization separation cubes and eventually four detectors detect the reflected light. These detectors are connected through an electronic processing means which evaluates the various signals for brightness comparison.

Another prior art reference is U. S. Patent No. 5, 442, 489 to Yamamoto et al relates to a magnifying apparatus. A polarized light irradiates an object and the reflected light is transmitted through a polarizing means and is in turn imaged by an imaging device. This arrangement magnifies and images practical areas of interest.

Applicant's article,"Polarized Light Examination and Photography of the Skin" describes the failings in the art to provide adequate viewing of surface and subsurface epidermis and is shown in FIG. 1. Light reflected from skin has two components : regular reflectance, or"glare"arising from the surface, and light backscattered from within the tissue.

The regular reflectance contains the visual cues related to surface texture, whereas the backscattered component contains the cues related to pigmentation, erythema, infiltrates, vessels and other intracutaneous structures. Unlike the backscattered component, regular reflectance preserves the plane of polarization of polarized incident light. Thus, viewing skin through a linear polarizer, under linearly polarized illumination, separates the two components of tissue reflectance. When the planes of polarization are parallel, images with enhanced surface detail are obtained. When the planes are orthogonal, wrinkles and surface detail disappear, and an enhanced view of vasculature and pigmented lesions is obtained.

The prior art discloses various devices and methods that accomplish surface irradiation and reflection detection. However, none of the prior art devices or methods provides a means or method of illuminating a surface and then viewing either surface or subsurface reflectance at the discretion of the user. Furthermore, the prior art does not disclose, teach or even suggest the preferred embodiment claimed.

The prior art also requires elaborate and often fixed setups to perform any type of surface analysis. These setups usually require the surface of interest to be moved past a positioned optical array. There is little teaching of portable units which would enable the user to perform imaging in remote locations or to manipulate the illuminator source with respect to the object being viewed.

Another problem in the art is cost. To set up these systems takes funds to procure the equipment needed. The art fails to account for the need for a practical system that is available to users with limited resources.

Another problem is space. These systems are usually quite large and need sufficient area to be set up and left in place.

Thus it would be desirable to have an apparatus that is portable and wearable by a user and that allows selective examination of surface and subsurface characteristics of an object or a material, with easily adjustable illuminating and viewing apparatus.

Summarv of the Invention : It is an object of this present invention to provide a device for irradiating a surface with polarized light in association with a polarized viewing means that provides separation between surface and subsurface reflectance.

It is another object to provide a device for viewing the surface or subsurface reflectance alternatively at the discretion of the user.

It is another object to provide a device with a light source and a viewing means of such a size and weight as to be comfortably wearable by a user.

The foregoing objects are met using a system for object or material inspection comprising most basically an illuminator, a support means, and a detector or viewing means. The illuminator itself comprises a housing having a first and second end. The housing encloses optical components and forms an optical path. The components within the housing include a light source located at one end thereof, a first polarizing means connected to the housing and located in the optical path between the light source and the object or material to be inspected. The housing also includes a lens located in the optical path between the light source and the object or material, an aperture located in the optical path intermediate the light source and the lens, and an optical filter located in the optical path between the light source and the object or material.

The support means includes a means for attaching the illuminator housing to the support means in a preferred orientation and a viewing means. The viewing means may be removably attachable to the support means. The viewing means, or detector comprises a second polarizing means though which an object or material is inspected.

Brief Description of the Drawings : Figure 1 is a plan view of a schematic representation of the two components of skin reflectance as discussed in the prior art.

Figure 2 is a perspective view of a preferred embodiment of the present invention.

Figure 3 is a diagrammatic view showing the relationship of the internal elements of the irradiating source of the housing of Fig. 2.

Figure 4 is a plan view depicting the aperture of the irradiating source of Fig. 3.

Figure 5 is a perspective view of an individual using a preferred embodiment of the present invention.

Figure 6 is a diagrammatic view showing the convection cooling flowpath through the housing.

Figure 7 is a schematic view showing an embodiment of the invention wherein the support means for the illuminator is free-standing system, not a head gear system.

Detailed Description of the Invention : Referring now to the figures, in which like reference numerals refer to like elements throughout, Figures 2-6 show a device 10 for object or material analysis.

Device 10 includes a support means 12 and an illuminator 14. Illuminator 14 is fixedly attached to support means 12 in a preferred orientation. This arrangement allows for illuminator 14 to be aligned in unison with the position of support means 12 so as to eliminate adjustment variables during operation of the device. Support means 12 comprises a support adjustable means 16 for maintaining the preferred orientation of support means 12. One skilled in the art would recognize that the use of a strap, VELCRO (R) hook and loop fasteners or other types of fasteners could be used as support adjustable means 16.

Further, a bridge means 18 for supporting illuminator 14 is fixedly attached to support means 16. Many types of well known objects or materials including plastics, cloths or composites can be used to form bridge means 18. Also, bridge means 18 aids in maintaining the preferred orientation of support 12 while in use. Filters 20 and 22 are polarizing elements that may be located on support 12 and are proximate each other. Further, filters 20 and 22 are maintained in a preferred orientation with respect to illuminator 14. The orientation is such that each of the illuminator 14 and filters 20 and 22 will face an object or material of interest simultaneously. Each filter is combined with a magnifying lens 20'and 22', which may be of a fixed or variable magnification, selected to provide a magnified view of the surface being inspected which coincides with the illuminated area. However, it should be recognized that the dual filter and lens construction shown by filters 20 and 22, and lenses 20'and 22'can be replaced by a single filter/lens design. Also, separate filters and/or lenses can be used in conjunction with the device in place of an integral filter and lens arrangement.

The embodiment shown in FIGS. 2 and 5 includes a support means configured to be worn on the head of a user, such as a physician in an operating room or like environment. It should be appreciated that other embodiments can be envisioned that fall within the spirit and scope of the invention, such as internal medicine examination devices, which use fiber-optic means for both illuminating and viewing internal organs or the like. Fiber optics may also be used to detect and send detected signals to a monitor onto, or through which, an image of the material or object to be inspected may be displayed Electronic detection of the image may also be employed, such as with an electronic camera. In such case, in particular, illuminating and detected light may be outside the visible spectrum, for example in the non-infrared or ultraviolet. Non-infrared light is useful for identifying deep blood vessels within or below the skin. The invention can be used for enhancing the examination of any object in which specular and diffuse reflectance are desired to be viewed separately. For example, the invention may be used in viewing gem stones for cut and clarity wherein it is desirable to see both surface and sub-surface characteristics of the gem stone. However, the invention need not be restricted to being worn on the head of a user.

The illuminator 14 incorporates a plurality of elements, which in concert, provide substantially uniform polarized light to irradiate a site of interest. Illuminator 14 includes a housing 24, having a first end 26 and a second end 28, which forms an optical path and houses the illuminator elements. The preferred orientation is positioning first end 26 so that it is closer to the filters 20 and 22 than second end 28. A power supply means 30 may connect to the internal components of the housing 24 to supply power to the system's components requiring the same. Power supply means 30 may be external electrical power, as shown in the Figures, or may be portable such as, for example, a battery pack worn at the waist of a user.

The elements of the illuminator 14 are better seen in FIG. 3, which is a diagrammatic representation of the relationship of the internal elements of the device. First, a light source 32 is used to provide light to illuminate the object or material to be inspected. Lamps can be obtained in various sizes and luminosities. Light source 32 is located inside a reflector 34 preferably at the focus of reflector 34. The reflector 34 is an elliptical shape, opening out such that the light reflected from the elliptical shape is directed down the optical path formed by the structure of the housing 24. The reflected light is focused by reflector 34 at an aperture 36. The focused light passes through aperture 36 and optical filter 38, which may be chosen to transmit visible light, non-infrared light or ultraviolet light. The location of these optical elements is not critical, however, the aperture is chosen to pass a uniform field efficiently, and care should be taken in maximizing the amount of light incident on the object or material of interest. There are a number of various elements that can be chosen as light source 32. Some of these include, but are not limited to, incandescent lamps, tungsten- halogen lamps, various bulbs and filament arrangements, extremely powerful sources such as a Xenon lamp. The use of polarizers (see below) limits the total visible light to only about 1/10 of that occurring without the polarizers. Therefore a bright light source is needed.

However, a typical light source 32, having the required intensity, generates a vast amount of heat, typically 20-40 Watts. Since light source 32 is confined inside housing 24, the heat needs a way to be dissipated. Therefore, in order to dissipate the heat generated by light source 32, a cooling means is located within the housing 24 at the second end 28 thereof.

Illuminator 14 and its housing 24 may also be in a hand held form (not shown) with the filter/lens assembly 20, 22, 20' and 22'worn on the head. Housing 24 may be in the same form and shape as that shown in the Figures, but may be hand held to permit greater freedom of movement for illuminator 14. For example, illuminator 14, housing 24, and power supply 30 may all be contained in a self-contained hand held unit. There may also be clips or other attachment means (not shown) on the head gear assembly which allow illuminator 14 and housing 24 to be removably attachable to the head gear such that illuminator 14 may be worn on the head or may be hand held.

In the embodiment shown in figures 1-6, the cooling means which is used to dissipate the heat generated by light source 32, is a convection cooling means, which includes an exhaust fan 40. The exhaust fan 40 provides sufficient convective cooling to the illuminator components located within the housing by drawing cooler air from outside illuminator 14 into the interior of housing 24. The air is drawn into and then out of the device via the exhaust fan 40 as illustrated in FIG. 6. There are openings 42 in housing 24 that allow air to flow into the system. These openings 42 could be constructed in many well known fashions including holes, slits and perforations. The minimum size requirement of the openings must be enough to allow a sufficient amount of air to enter and cool the system. The cooling means is incorporated into the system to extend the useful life of device 10. Further, by maintaining the device 10 at a moderate temperature, a user can handle device 10 safely and without the need for special gloves or other protection from bum injuries.

Such a cooling device would be necessary especially with a light source such as a Xenon lamp.

The power adapting means 44 can be a switching device, AC/DC converter, battery or the like. Further, it should be recognized that power adapting means 44 is also electrically connected (not shown) to light source 32. There may also be an embodiment of the invention wherein power supply means 30 is contained in housing 24 such that no cord is required to connect the user to either a wall outlet or other physically distant power supply. The power supply means may be a long-lived battery pack, for example, which may be worn at the waist of a user, or with an infrared or photosensing switch mechanism to activate the power supply at a given signal. In this way the entire system unit 10 is self-contained and external cords are eliminated, thus reducing the risk of accident or injury due to interference with a power cord, such as moving too far from an outlet or tripping over a cord.

Infrared filter 38 is used to attenuate infrared light that is generated by light source 32. If too much infrared light is directed at the object or material of interest for a prolonged period of time, unwanted heating and/or damage can occur to the surface. For instance, if as disclosed, the object were human skin, prolonged exposure to infrared light might prove uncomfortable or harmful, for example by altering blood perfusion, which could result in an erythematous reaction.

As indicated above, elliptical reflector 34 is selected to focus a beam of light at aperture 36 such that the light passing through aperture 36 is substantially uniform throughout the cross-section of aperture 36. A lens 46 is then used to project a real image of aperture 36 onto the object to be inspected, resulting in a substantially uniform bright spot of illumination. The spacing between lens 46 and aperture 36 is selected to produce a conjugate ratio to project a magnified image of the aperture onto an object, for example, skin, at a working distance. The working distance is substantially a distance from lens 46 equal to the focal plane of magnifying lenses 20'and 22'. In one embodiment of the invention, lens 46 is a fixed focal length lens and is not adjustable. This eliminates operational variables during use of the system.

A first polarizing means 48 is preferably located at an end of the housing for example, first end 26. Polarizing means 48 is preferably a linearly polarizing filter that polarizes the light from light source 32 in a single plane of polarization. This allows for polarized light to irradiate the object or material of interest as shown in FIG. 5. Polarizing filter 48 is rotatable to any position between a first position and a second position. By rotating polarizing lens 48 different planes of polarization can be achieved.

Reflector 34, infrared filter 38 and lens 46 are all spatially maintained in the system via a plurality of attachment means 50. The plurality of attachment means 50 maintain each of the respective elements in the optical path but with minimal contact with the housing 24 to limit conductive heating of the housing, and to allow for the air flowing within the housing to circumvent and cool the elements. Further, this provides for a more efficient cooling of the air in the system and cooling of the individual elements.

Attachment means 50 are adhesive spacers that maintain the elements in a desired orientation and relative position while allowing gaps 52 for flowing air to pass by. FIG. 4 shows the adhesive spacers being constructed by placing a predetermined amount of an adhesive in intervals along a surface such as the housing or aperture. Then, by overlaying the adhesive with an element and adhering the element to the surface, a space is formed at the same time the element becomes rigidly attached. In FIG. 4, infrared filter 38 would be attached to aperture 36 via adhesive spacers 50.

Though adhesive spacers 50 have been disclosed as the attachment means, other types of attachment and spacing means could be used. This includes welding, soldering and other mechanical joining means being used to adhere the elements to their respective surfaces.

Also, clamps which grasp the elements of the housing while allowing air to flow through may be used.

In FIG. 5, the linearly polarized light impinges on the surface of the material or object under examination at an angle. When incident and detected planes are parallel, the regular (Fresnel) reflectance component is attenuated less than the depolarized backscattered component. This causes relative enhancement of the regular reflectance component. When the incident and detected planes of polarization are perpendicular (crossed), the regular reflectance is entirely eliminated from detection. Non-polarized light, directed at a surface, can be viewed by its reflectance properties. Light that is transmitted to and reflected from a surface becomes polarized by the surface itself. Further, polarized light that is transmitted to and reflected from a surface can show different parts of surface reflectance. Linearly polarized light that irradiates a surface and is viewed at an angle of reflectance can show surface characteristics. However, rotating the polarizing means such that the incident and detected planes of light are perpendicular will best show subsurface characteristics. This requires that the detection takes place such that the angle of reflectance allows the surface to act as a second polarizing means.

In the claimed invention, a first and second polarizing means are used in concert with each other. Illuminator 14 irradiates the surface with linearly polarized light generated by light passing through the first polarizer 48 oriented in a first position. The backscattered light is detected by a user via a second polarizing means which is a set of fixed polarized filters 20 and 22 and magnifying lenses 20'and 22'. In the first position, the plane of polarization of first polarizer 48 is parallel to the plane of polarization of filters 20 and 22. Thus, the light reflected from the surface allows the user to view enhanced surface properties. By rotating the first polarizer 48 or polarized filters 20 and 22 to a second to a second position 90 degrees from the first, perpendicular axes of polarization are formed between first polarizer 48 and polarized filters 20 and 22. This allows the user to view subsurface reflectance, and therefore view enhanced subsurface features of, for example, skin, tissue, or other material to be inspected.

The change between the incident and detected planes from parallel to perpendicular is caused by the rotation of polarizer 48 from one position to another and preferably from a first predetermined position to a second predetermined position. The total amount of rotation between the first and second predetermined positions is preferably 90°. The user can also choose to vary the amount of reflection of surface reflectance by adjusting the polarizers intermediate the first and second predetermined positions.

The cooling flow path is seen in FIG. 6. Air, from outside the system, is drawn into the system through openings 42 by exhaust fan 40. The air follows the path of the arrows. It flows around the edges of infrared filter 38 and reflector 34 through spaces created by adhesive spacers 50 which hold filter 38 and reflector 34 in their respective positions within housing 24 thus cooling all the elements. The air then continues out of the system past the exhaust fan 40.

Although the cooling device has been disclosed as an exhaust fan, other types of cooling devices such as thermoelectric cooling systems can be employed. A liquid fluorocarbon refrigerant system, such as a miniaturized refrigeration system, or the like, can be used to maintain a constant temperature in the system. Further, a liquid cooling system 54 could be used wherein water in a circulating path is used to circulate cool water through the device. Here, a means such as a tube 56 can be used to circulate cool water through the device. Heat from the system is then transferred to the cool water which is in continuous circulation. The water is then cooled and recirculated back through the system.

Although polarizer 48, a polarizing filter, has been disclosed at the end of the housing, it should be recognized that the polarizing filter 48 can also be incorporated within the housing or as a coating on one of the other optical elements. Further, to rotate the polarizer 48 from the first position to the second position, it could be attached to an external lever that would be used to rotate the polarized lens within the housing. This allows for the placement of the polarized lens 48 in various regions of the housing so long as it is located within the optical path formed between the light source and the object or material being irradiated.

As with polarized filter 48, infrared filter 38 can be placed in various regions within the housing so long as it is located within the optical path formed between the light source and the object or material being irradiated.

Although the present invention has been described with preferred embodiments, workers skilled in the art will recognize that changes may be made inform and detail without departing from the spirit and scope of the invention.

Figure 7 shows an embodiment of the invention wherein the light source is mounted on a support means 12 that may be a table structure, or other free-standing structure, as opposed to head gear. Filters 20 and 22 may be integral to the support means such that illuminator 14 and filters 20 and 22 simultaneously face the object or material to be inspected.

Additionally, fiber optics, light pipes or liquid media may be used as illuminator (not shown) to transfer light from, for example, a table top or floor mounted light source 32 to the viewing destination. The illuminator could then be hand-held, attached to a headgear system, or mounted on a free-standing unit, even using an externally located light source connected to the illuminator.