Abstract:
A probe cover for medical thermometer has a matching feature for preventing its use with an incompatible thermometer. A mechanical matching feature of the probe cover includes at least one of a fold, a step, or a series of holes or indentations that are respectively matched to a ridge, a valley or series of pins formed on the front end of a compatible thermometer. When applied to the compatible thermometer, the mechanical matching feature permits the probe cover to be fully seated on and retained by the probe, thereby placing the thermometer in condition for use. Alternatively, an opto-electronic matching feature of the probe cover includes a reflective layer for use with an opto-electronic detection circuit of a compatible thermometer. When applied to the compatible thermometer, the opto-electronic detection detects the reflective layer and places the compatible thermometer in an operational state for use.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is a divisional application of U.S. patent application Ser. No. 12/675,877, filed on Dec. 29, 2012, which was the National Stage of International Application No. PCT/US09/69528, filed on Dec. 24, 2009, which claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/203,641, filed on Dec. 29, 2008 and entitled “Matching Probe Cover for Infrared Thermometer,” the contents of all of which are hereby fully incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to thermometers, and more particularly, to medical thermometers that employ disposable or reusable probe covers. 
       BACKGROUND OF THE INVENTION 
       [0003]    The temperature of a human or animal, can be measured either by means of thermal conduction or thermal radiation. In the former case, a temperature sensing probe may be positioned inside the patient&#39;s body cavity or on the skin surface to obtain an intimate contact for conductively receiving thermal energy indicative of a surface temperature of a patient-measured body site. In the latter case, a naturally-emanated electromagnetic radiation in the mid- and far-infrared spectral ranges may be detected by an appropriate non-contact sensor, whose output signal is indicative of the surface temperature of a patient-measured body site (for example, in proximity to the tympanic membrane). A combination of a sensor, electronic circuit and other components form an infrared (IR) thermometer, which is an opto-electronic instrument. 
         [0004]    Many medical thermometers, either contact or non-contact, use sanitary probe covers which envelope the probe and prevent cross-contamination of patients and soiling of the probe. In a contact probe cover, thermal energy (heat) is transmitted by means of thermal conduction. Thus, requirements for the probe cover must be compatible with the thermally conductive properties of the probe cover material. Various conventional covers for such contact thermometers are described in many patents, for example, in U.S. Pat. No. 4,159,766 to Kluge, which is incorporated by reference herein in its entirety. 
         [0005]    In order to measure a surface temperature of an object by means of IR radiation, the probe of the IR thermometer is aimed at the area of interest. For example, in order to measure the temperature of a tympanic membrane and the surrounding tissues, the probe is placed into the ear canal. Before the insertion, a probe cover is typically installed onto the probe to envelope its parts that otherwise might come in contact with the tissues of the ear canal. 
         [0006]    A typical prior art infrared thermometer  70  is illustrated in  FIGS. 1   a  and  1   b . The thermometer  70  includes a front end  77 , from which an infrared probe  72  projects, for example, with an orientation suitable for placement of the probe  72  in the ear canal. A probe cover  71  is positioned to be placed over the probe  72  for eliminating any direct contact between the probe  72  and tissues of the ear canal. A power button  76  is provided for powering the circuitry of the thermometer  70 . A start button  78  is provided to engage the circuitry to perform a temperature measurement, and a display  75  is provided, for example, to indicate a current condition or status of the thermometer  70  and/or the results of a current temperature measurement. A probe cover detector  73  is positioned near a base of the probe  72  for detecting that the probe cover  71  has been placed over the probe  72 , and may for example interact with the circuitry to permit operation of the thermometer  70  only when installation of the probe cover  71  has been detected. After a temperature measurement has been made, a probe cover ejector  74  elevates the front end  77  of the thermometer  70  relative to the probe  72  in order to eject the probe cover  71  from the probe  72 . 
         [0007]    The probe cover  71  is not only required to provide a sanitary protection against contamination of the probe by ear wax and other soiling biological compounds, but it must possess other properties for accurate temperature measurement by means of detecting an associated IR signal. Such properties, for example, include a good optical transparency of the probe cover in the spectral range of interest, low directional distortion of optical rays, tight manufacturing tolerances, stability of the optical properties during installation onto the probe, long term stability, and the like. Suitable probe covers for IR thermometers are exemplified by U.S. Pat. No. 5,088,834 issued to Howe et al. and U.S. Pat. No. 5,163,418 issued to Fraden et al., each of which is incorporated by reference herein in its entirety. Most prior art probe covers are formed to surround a longitudinal axis of a thermometer probe. 
         [0008]    As a rule, a prior art probe cover intended for a medical thermometer includes three portions being disposed along the probe longitudinal axis y (see, e.g.,  FIG. 2   a ): 
         [0009]    1) a proximal or “base” portion  102  provided for physical retention of the cover by the thermometer probe or front end of a thermometer housing. The proximal portion  102  may contain an offset  3  for interaction with the retention devices of the probe. This offset  3  is disposed along a transverse axis x that is substantially normal to longitudinal axis y. A brim  7  may or may not be part of the proximal portion  102 . The proximal portion  102  has an opening  105  through which the probe is inserted during a probe cover installation. Instead of or in addition to the offset  3 , the proximal portion  102  may have a snug fit over the probe, thus using friction as a retention force (see, e.g.,  FIG. 2   e ), 
         [0010]    2) a middle or “body” portion  101  provided for enveloping the sides of the probe. The middle portion  101  includes a rigid or pliant wall  1 . The middle portion  101  may be prefabricated, or it may be formed during the probe cover installation by stretching wall  1  to match the probe length, and 
         [0011]    3) a distal or “tip” portion  100  provided for enveloping the optical end of the probe of an IR thermometer or the sensing part of a contact thermometer. This portion  100  contains a membrane  2  which is substantially transparent for IR radiation (for an IR thermometer), or is thermally conductive (for a contact thermometer). The membrane  2  may include a polymer film (for an IR thermometer, in thickness ranges from as little as 0.0005 in. to as much as 0.005 in.). The IR radiation passes through the membrane  2  before entering the probe where it is detected by the IR sensor. In effect, the membrane  2  of the probe cover works as an optical filter, and often is alternatively called a “lens filter.” 
         [0012]    Typical materials for fabricating the probe covers are polyethylene, polypropylene, and copolymers of polyethylene and polypropylene.  FIG. 2   a  shows a prior art unitary probe cover (as taught for example by U.S. Pat. No. 5,088,834) which is fabricated as a single piece.  FIG. 2   b  shows a two-piece probe cover (as taught by U.S. Pat. Nos. 4,662,360, 5,293,862 and 5,179,936, each issued to O&#39;Hara et al. and incorporated by reference herein in their entirety) where a membrane  6  is welded onto a frustoconical body  4 . In the probe cover of  FIG. 2   b , a bottom ring  5  is provided for affixing the probe cover to the probe as part of a proximal portion. Probe covers generally have shapes that follow a body of rotation around a longitudinal axis y. 
         [0013]    Probe covers may be attached to the probe or the IR thermometer housing by various mechanisms.  FIG. 2   c  once again shows the offset  3 , which is an extension of wall  1  of the probe cover in the proximal portion  102 . The offset  3  engages a nipple  12  that is part of a probe  8  of the IR thermometer when the probe cover is installed onto the probe  8 . The nipple  12  is disposed along a transverse axis x. 
         [0014]    Another known way of attaching a probe cover to a probe is shown in  FIG. 2   d .  FIG. 2   d  illustrates a hook  10  (also illustrated in  FIG. 2   b ) which is supported by a neck  11 . The neck  11  is an extension of a ring  5 . When the probe cover is installed onto the probe  9 , hook  10  engages a retention skirt  49  of a probe cover  9 . The retention portion  40  of hook  10  is disposed along the transverse axis x. Alternatively,  FIG. 2   e  shows a probe cover  4  installed on a probe  9 , which includes a retention ring  5  that enables the probe cover  4  to be retained by a frictional force applied to the probe cover  4  along the transverse axis x. 
         [0015]    In the prior art probe covers illustrated in  FIGS. 2   a - 2   e , a probe cover body is formed along the longitudinal axis y, having retention elements formed along the transverse axis x. 
         [0016]    Known prior probe covers, while having various shapes and methods of retention, often may be interchanged between different types of thermometers. This is undesirable, and may for example cause a mismatch between the type of a membrane  2  (material, thickness and shape) and the thermometer calibration and, as a result, cause unacceptably high errors in temperature measurement. It is important to use only a correct (matching) probe cover with a particular thermometer. However, common matching techniques such as affixing an identification code on a probe cover are typically insufficient for preventing use of a wrong probe cover. Thus, a more direct method for preventing usage of a foreign probe cover on a thermometer is desirable. 
       SUMMARY OF THE INVENTION 
       [0017]    The present invention is directed to a probe cover that encourages proper use with a thermometer probe by forming matching elements on a proximal portion of the probe cover to be matched with corresponding elements on a front end of the thermometer in proximity to the probe. The matching elements have complementary features to the corresponding elements on the thermometer probe (for example, complementary or interlocking shapes) that form a “key-lock” pair when the probe cover is installed onto the probe. A mismatching of non-corresponding elements makes it impossible either to securely position the probe cover on the probe and/or operate the thermometer. The method of matching can be used for any type of a medical thermometer having a probe cover (including, for example, IR and contact thermometers). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawings of illustrative embodiments of the invention in which: 
           [0019]      FIGS. 1   a  and  1   b  show a front perspective view and a rear perspective view of a prior art infrared thermometer, respectively; 
           [0020]      FIGS. 2   a  and  2   b  shows a unitary prior art probe cover and a two-piece prior art cover, respectively; 
           [0021]      FIGS. 2   c  and  2   d  show partial views of prior art probe covers having offset and hook retention mechanisms, respectively; 
           [0022]      FIG. 2   e  shows a prior art probe cover including a friction ring for retention; 
           [0023]      FIG. 3  provides a side cross-sectional view of a unitary probe cover according to an embodiment of the present invention; 
           [0024]      FIG. 4   a  is a partial view of a probe cover according to another embodiment of the present invention; 
           [0025]      FIG. 4   b  is a partial view of a probe cover according to a further embodiment of the present invention; 
           [0026]      FIG. 5   a  shows a front elevational view of a probe cover according to another embodiment of the present invention; 
           [0027]      FIGS. 5   b  and  5   c  respectively show a side cross-sectional view of a probe and probe cover according to a further embodiment of the present invention and a front elevational view of the probe; 
           [0028]      FIG. 6  shows a partial cross-sectional view of a probe cover according to another embodiment of the present invention; 
           [0029]      FIG. 7  shows a front elevational view of a probe cover according to another embodiment of the present invention; 
           [0030]      FIG. 8  shows a front elevational view of a probe cover according to a further embodiment of the present invention; 
           [0031]      FIG. 9  shows a front elevational view of a probe cover according to another embodiment of the present invention; 
           [0032]      FIGS. 10   a  and  10   b  respectively show a side cross-sectional view and a front elevational view of a probe cover according to a further embodiment of the present invention; 
           [0033]      FIG. 11   a  shows a front elevational view of a probe cover according to another embodiment of the present invention; 
           [0034]      FIG. 11   b  shows a cross-sectional view through a portion of a brim of the probe cover of  FIG. 11   a;    
           [0035]      FIG. 12  shows a side view of a probe cover according to another embodiment of the present invention; 
           [0036]      FIG. 13  shows a side cross-sectional view of a probe cover according to another embodiment of the present invention; and 
           [0037]      FIG. 14  shows a partial cross-sectional view of a probe cover according to a further embodiment of the present invention. 
       
    
    
       [0038]    Like reference numerals are used in the drawing figures to connote like components of the probe cover. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0039]    A probe cover for an infrared (IR) thermometer is a sanitary envelope which forms a barrier between the instrument and the patient. For the purpose of illustrating principles of the present invention, several probe covers are described and shown for application to an infrared thermometer used in measuring temperatures in an ear canal of a human or animal. The present invention is however equally applicable to probe covers used in a variety of other contexts, for example, including medical contact thermometers that take conductive temperature measurements from a body cavity or surface of a human and veterinary thermometers used for determining the temperature of an animal. 
         [0040]    In the presently-described examples, a distal portion of the probe cover is designed to cover a window of a probe housing through which IR energy is received in order to measure temperature. The material for the probe cover&#39;s distal portion (that is, for its “optical portion”) is preferably selected from the group of polymers which have significant transparency in the spectral range between 3 and 15 μm. Examples of suitable polymers include polyethylene, polypropylene, and copolymers of polyethylene and polypropylene. As a rule, the thickness of the optical portion of the cover is preferably on the order of 20 micrometers. This thickness provides acceptable IR transmission characteristics, as well as an acceptable mechanical strength. As shown for example in  FIG. 3 , a body  1 ,  2  of the probe cover is substantially symmetrical around a longitudinal axis y. 
         [0041]    A probe cover, when installed onto the probe, may be retained by one of many methods known in the art, some of which are described above. A preferred embodiment of a probe cover according to the present invention includes middle and distal portions which are not substantially different from those of above-described prior art. It should be noted that the present invention is principally directed to providing additional features in a proximal portion of a probe cover for precisely matching the probe cover to a corresponding thermometer. 
         [0042]    The probe cover of  FIG. 3  is a unitary IR probe cover having a membrane  2  adjacent to an IR window  51  of the IR thermometer&#39;s probe  8 . Side wall  1  of the probe cover envelopes sides of the probe  8 . A circular offset  3  of the probe cover snaps over nipples  12  of the probe  8 , thus assuring retention of the probe cover when installed onto the probe  8 . Preferably, two or more nipples  12  are opposingly provided on the sides of the probe  8 . As shown in  FIG. 3 , nipples  12  and offset  3  are disposed along a transverse axis x that is normal to the longitudinal axis y. 
         [0043]    In the proximal or base portion of the probe cover of  FIG. 3 , a brim  7  is provided and disposed in a direction substantially parallel to the transverse axis x. The brim  7  includes a pre-formed fold  25  that extends upwardly in a direction parallel to the longitudinal axis y. The fold  25  may be continuously formed around the longitudinal axis y, or may be broken into two or more segments. A front end  17  of the IR thermometer contains at least one pin  23  that enters the fold  25  as the probe cover is installed and seated on the probe. Preferably, two or more pins ( 23  and  22 ) are provided on the IR thermometer front end  17  for entering the fold  25 . If the pins  22  and  23  and the fold  25  are not matched (for example, if the probe cover is not intended to be used with the IR thermometer), the mismatch (between the shapes and positions of fold  25  and pins  23  and  22 ) prevents the probe cover from sitting deeply enough on the probe  8  to be seated. As a result, the offset  3  is not able to engage with the nipples  12 , and the probe cover is not effectively retained for use on the probe  8 . 
         [0044]    Alternatively to the pins  22  and  23 , a matching ridge  29  may be formed as part of the IR thermometer front end  17  (see, e.g.,  FIG. 4   a ). For a secure seating of the probe cover on the probe  8  that causes the nipples  12  to be engaged with the probe cover offset  3 , ridge  29  must have a complimentary shape to fold  25 . The fold  25  and the corresponding pins  22  and  23 , or the ridge  29  are substantially disposed along a matching axis y′ that is substantially parallel to the longitudinal axis y and normal to the transverse axis x. Having a ridge  29  that is too wide or is centered at a wrong distance D 2  from the longitudinal axis y for a particular probe cover, will prevent such probe cover from being retained on the probe. 
         [0045]    A fold  25  is just one suitable example of a mechanical mating feature according to the present invention. Another example is a dip  61  (see, e.g.,  FIG. 4   b ) provided on the brim  7 , with a complementary valley  62  provided on the thermometer front end  17 . The dip  61  is essentially a half fold substantially formed along matching axis y′ that is parallel to the longitudinal axis y and perpendicular to the transverse axis x. In the half fold arrangement, the brim  7  extends laterally outwardly from the matching axis y′ rather than forming the second half of the fold as illustrated in the fold  25  of  FIG. 4   a.    
         [0046]    Alternatively, a combination of a dip and a fold (or several of them) may be also employed in the probe cover and matched with the corresponding complementary features on the thermometer. 
         [0047]    In each of the above-described embodiments of the present invention, the mating features such as a fold  25  and dip  61  shown in  FIGS. 3 ,  4   a  and  4   b  (formed along the matching axis y′) and their corresponding mating features  22 ,  23  and  29  formed on the probe are positioned further from the longitudinal axis y than the retention features such as offset  3  and nipple  12  (see, e.g., respectively corresponding distances D 2  and D 1 ). 
         [0048]    The mating features on the IR thermometer may further be aligned with a probe cover ejector. For example, after a temperature measurement is complete, the probe cover can be removed (ejected) from the probe by disengaging nipples  12  from offset  3  (see, e.g.,  FIG. 5   b ). A disengagement can be accomplished by a simple manual pulling off of the probe cover. Alternatively, the disengagement may be assisted by an ejector that is part of the thermometer. 
         [0049]      FIG. 5   a  depicts a front elevational view of the front end  17  of the thermometer as viewed along longitudinal axis y. No probe cover is installed.  FIG. 5   a  illustrates a ridge  29  broken into two segments  29   a  and  29   b . In between these segments, two ejectors  50   a  and  50   b  are positioned. The ejectors are normally hidden below the surface of the front end  17 , and have shapes and/or locations that are not matching the shape (for example, being wider than) and/or location of the ridge  29 . 
         [0050]    Ejection of a probe cover is facilitated, for example, by moving ejectors  50   a  and  50   b  upwardly in along axis y′. Because the ejectors  50   a ,  50   b  do not match the shapes of the segments  29   a ,  29   b , the ejectors  50   a ,  50   b  when operated will not fully enter the fold  25  of the probe cover, and will act therefore to push the probe cover upwardly in a direction parallel to the axis y. The IR thermometer may include one or more ejectors. Each ejector is preferably positioned adjacent to one of the nipples  12  of the IR thermometer. 
         [0051]    Alternatively, the ejectors may be configured to serve a dual purpose: providing a matching feature for retaining the probe cover, as well as an ejecting feature. For example, as illustrated in  FIG. 5   b , when ejectors  50   d  and  50   e  are partially retracted (that is, when only portions  50   c  extend above an upper surface of the front end  17 ), the ejectors  50   d  and  50   e  may serve as ridges for mating with the probe cover fold  25  as illustrated in  FIG. 3 . When partially retracted, the portions  50   c  provide just enough height to match with the fold  25 , and allowing the probe cover  111  to slide sufficiently downward for engaging the offset  3  and nipples  12 . However, when fully extended in a direction  112  as shown in  FIG. 5   b , the ejectors  50   d ,  50   e  will push the probe cover  111  outwardly and disengage offset  3  from nipple  12 . Preferably at least two ejectors  50   d ,  50   e  are positioned near two respective nipples, making two nipple-ejector pairs. Each pair is preferably disposed in opposition along the sides of the probe  8 . Each ejector is disposed along the axis y′ that is parallel to the longitudinal axis y.  FIG. 5   c  illustrates a front elevational view of the probe  8  which further shows the positioning of the ejectors  50   d ,  50   e.    
         [0052]      FIG. 6  illustrates probe cover according to the present invention which includes an outward fold  26  on the brim  7  for mating with valley  27  formed in the front end  17  of the thermometer. The fold  26  on the brim  7  extends downwardly along the axis y′ that is parallel to the longitudinal axis y. 
         [0053]    Numerous other shapes and mechanical mating arrangements can be formed on the proximal portion of the probe cover and the corresponding front end  17  or probe  8  of a thermometer. For example, as shown in  FIGS. 7 and 8 , a circular brim  19  may be trimmed or relieved with a cut  38  forming a chord or linear segment between two points on the perimeter of the circular brim  19 , to facilitate matching or clearance in relation to a pin  14  projecting from the thermometer front end  17 . Any number of additional cuts may be added as needed for a particular design. For example,  FIG. 8  show a probe cover having three cuts  18  made equidistantly around the brim  19 . The cuts  38  and  18  are made to match the positions of one or more pins  14 , or other complementary features disposed on the thermometer front end  17   
         [0054]    Another embodiment of the present invention is shown in  FIG. 9 . In this embodiment, one or more holes  20  are formed in the brim  7  of the probe cover along matching axes y′ that are parallel with the longitudinal axis y. In an embodiment having at least two holes  20 , mating pins  13  and  14  are positioned on the front end  17  to match the sizes and locations of holes  20 . For example, the lateral distance of the pins  13  and  14  from the longitudinal axis y and the angular relationship between the pins  13  and  14  with reference to the longitudinal axis y is matched by the positioning of the holes  20  in the brim  7  of the probe cover when the probe cover is seated on the probe 
         [0055]    As an alternative to the holes  20 , conical or similarly-shaped extensions  21  can be formed on brim  7  as depicted in  FIGS. 10   a  and  10   b . For a unitary probe cover, they may be preferably formed by use of a thermoforming technology. In this case, mating pins  22 ,  23  formed on the front end  17  include conical or similarly-shaped features  22   a ,  23   a  for effectively mating with the conical or similarly-shaped extensions  21 . 
         [0056]    Another embodiment of the present invention having yet another mechanical mating feature is shown in  FIG. 11   a . In  FIG. 11   a , the brim  7  has petals  15  formed by indentations (voids)  16  spaced around a circumference of the brim  7 . One or more mating pins (for example, the pins  13  and  14 ) on the thermometer front end  17  allows for the probe cover installation along longitudinal axis y. In this embodiment of the invention, the pins  13  and  14  are positioned to simultaneously enter the voids  16  between the petals to form a “key-lock” arrangement. The locking arrangement is shown in more detail in  FIG. 11   b.    
         [0057]    In another embodiment of the present invention illustrated in  FIG. 12 , a two-piece probe cover  55  has a matching feature formed as semi-oval cut-outs  41  in the bottom ring  5  that match corresponding semi-oval fingers  42  of the front end  17  when the probe cover is installed and seated. Any number of other complementary shapes may alternatively be used for the cut-outs and corresponding fingers. The cut-outs  41  are provided along the axes y′ that are parallel to the longitudinal axis y. 
         [0058]    The above described matching features all are of a mechanical nature. In another embodiment of the present invention, a non-mechanical matching feature between the probe and probe covers is provided using opto-electronic devices. As shown for example in  FIG. 13 , a brim  7  of the probe cover is provided with a reflective layer  30  formed on an underside surface of the brim  7  facing a thermometer body  31 . The layer  30  may include, for example, an aluminum foil that is welded, glued, sputtered or otherwise deposited on the underside surface brim  7 . Alternatively, the reflective layer  30  may be a painted layer of selected color. 
         [0059]    As illustrated in  FIG. 13 , the thermometer body  31  carries a light emitter  32  and light detector  33  that together form an opto-coupler. When a probe cover with the reflective layer  30  is installed, the detector  33  is configured to receive a light beam  34  that is transmitted by the light emitter  32  and reflected by the layer  30 . Detector  33  will respond with a changing electrical signal, thus signaling a detection circuit in the IR thermometer that a suitable probe cover has been properly installed. If the detector  33  detects no reflection, or detects a reflection having a wrong intensity or mismatched spectral characteristics (color), the detection circuit preferably determines that a suitable probe cover has not been installed, and will prevent a temperature measurement from being initiated in the IR thermometer. 
         [0060]    If the reflective layer  30  has been painted with a particular color, the color of the emitter  32  should be substantially the same to allow for proper reflection of the emitted light. For example, if emitter  32  generates green light and the reflector  30  is also green, then there will be reflection of the emitted light which will then be detected by detector  33 . However, if emitter  32  generates green light and the selected color of the reflector  30  is red, there will be a negligible reflection of green light toward detector  33  and the device will indicate a mismatch, i.e., a proper probe cover has not been used. A spectral response of detector  33  should be matched with the spectral response of the emitter  32 . 
         [0061]    Alternatively, as shown in  FIG. 14 , the reflective layer  35  may be deposited on a side of brim  7  opposite to the underside. In this embodiment of the invention, the light beam  34  will travel through brim  7  on the way to detector  33 . This will not change the operation of the opto-coupler  32 ,  33  and detection circuit, provided that the brim  7  of the probe cover is suitably transparent. 
         [0062]    While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art as described herein that various changes in form and details may be made to the discloses embodiments without departing from the spirit and scope of the invention. For example, in relation to the embodiments having mechanical matching features, the embodiment of  FIG. 10  could be modified to provide pin features in the brim of the probe cover while providing conical or similarly-shaped extensions in the surface of the front end of the thermometer. In addition, in relation to the embodiments having non-mechanical matching features, the reflector and optical circuits could respectively be replaced with an electrical component (for example, a film resistor) and circuits for measuring a selected characteristic of the electrical component (for example, a selected resistance). 
         [0063]    Accordingly, the invention is to be limited only by the scope of the claims and their equivalents.