Medical thermometer having an improved optics system

Abstract

A medical thermometer including a curved mirror and a radiation sensor is disclosed. The radiation sensor is disposed relative to the mirror in a configuration whereby the mirror reflects away from the sensor radiation that passes through the radiation entrance and that is oriented outside a range of angles relative to the mirror, and reflects toward the sensor radiation that passes through the radiation entrance and that is oriented within a range of angles relative to the mirror.

1 . A medical thermometer, comprising:
 a housing having a radiation entrance;   a mirror having an axis disposed in the housing; and   a radiation sensor disposed in the housing relative to the mirror in a position whereby the mirror reflects away from the sensor radiation that passes through the radiation entrance and that is oriented outside a radiation range of angles from the axis.   
     
     
         2 . The medical thermometer of  claim 1  wherein the shape of the mirror is parabolic as defined by the equation y=ax 2 +bx+c, where a is not equal to 0, the parabolic shape having a vertex, a baseline tangent to the parabolic shape at the vertex, an axis of symmetry collinear with the axis of the mirror, and a focal point. 
     
     
         3 . The medical thermometer of  claim 2  wherein a is between approximately 0.01 and 2.0. 
     
     
         4 . The medical thermometer of  claim 2  wherein b is between approximately −2.0 and 2.0. 
     
     
         5 . The medical thermometer of  claim 1  wherein the radiation sensor includes a detection surface having a center point thereon and wherein the center point is disposed approximately at the focal point. 
     
     
         6 . The medical thermometer of  claim 5  wherein the normal to the detection surface is angled between approximately 25° and 35° from the baseline. 
     
     
         7 . The medical thermometer of  claim 2  wherein a is between approximately 0.07 and 0.09. 
     
     
         8 . The medical thermometer of  claim 7  wherein b is between approximately −0.02 and −0.01. 
     
     
         9 . The medical thermometer of  claim 8  wherein the radiation sensor includes a detection surface having a center point thereon and wherein the center point is disposed approximately at the focal point. 
     
     
         10 . The medical thermometer of  claim 9  wherein the normal to the detection surface is angled between approximately 31° and 32° from the baseline. 
     
     
         11 . The medical thermometer of  claim 10  wherein the radiation range of angles from the axis is from approximately −5° to 5°. 
     
     
         12 . The medical thermometer of  claim 1  wherein the radiation range of angles from the axis is from approximately −5° to 5°. 
     
     
         13 . The medical thermometer of  claim 1 , further comprising a filter positioned in the field of view of the radiation sensor and between the mirror and the radiation sensor, the filter being capable of passing only radiation having a predetermined range of wavelengths. 
     
     
         14 . The medical thermometer of  claim 13 , wherein the filter is capable of passing only radiation having wavelengths between about 7.5 μm and about 13.5 μm. 
     
     
         15 . The medical thermometer of  claim 13 , wherein the filter is a component of a radiation sensor assembly which includes the radiation sensor. 
     
     
         16 . A medical thermometer, comprising:
 a curved mirror having a vertex, a focal region and a baseline tangent to the mirror at the vertex; and   a radiation sensor having a center point on a detection surface, the center point being disposed at least approximately at the focal region and the normal to the detection surface being oriented at a detection angle with respect to the baseline, such that the sensor is configured to detect radiation reflected by the mirror.   
     
     
         17 . The medical thermometer of  claim 16  wherein the detection angle is an acute angle. 
     
     
         18 . The medical thermometer of  claim 16  wherein the mirror is at least approximately parabolic. 
     
     
         19 . The medical thermometer of  claim 18  wherein the shape of the mirror is parabolic as defined by the equation y=ax 2 +bx+c, where a is not equal to 0, and further wherein the focal region is a focal point, and the parabolic shape includes an axis of symmetry and a parabola vertex coincident with the vertex of the mirror. 
     
     
         20 . The medical thermometer of  claim 19  wherein a is between approximately 0.01 and 2.0. 
     
     
         21 . The medical thermometer of  claim 19  wherein b is between approximately −2.0 and 2.0. 
     
     
         22 . The medical thermometer of  claim 16  wherein the detection angle is between 30° and 35°. 
     
     
         23 . The medical thermometer of  claim 16  further including a radiation entrance such that the mirror is configured to reflect away from the radiation sensor radiation that passes through the radiation entrance and that is not oriented between a radiation range of angles from the axis of symmetry. 
     
     
         24 . The medical thermometer of  claim 19  wherein a is between approximately 0.07 and 0.09. 
     
     
         25 . The medical thermometer of  claim 24  wherein b is between approximately −0.02 and −0.01. 
     
     
         26 . The medical thermometer of  claim 25  wherein the detection angle is between approximately 31° and 32°. 
     
     
         27 . The medical thermometer of  claim 26  further including a radiation entrance such that the mirror is configured to reflect away from the radiation sensor radiation that passes through the radiation entrance and that is not oriented between a radiation range of angles from the axis of symmetry. 
     
     
         28 . The medical thermometer of  claim 27  wherein the radiation orientation range of angles is between approximately −5° and 5° from the axis of symmetry. 
     
     
         29 . The medical thermometer of  claim 16 , further comprising a filter positioned in the field of view of the radiation sensor and between the mirror and the radiation sensor, the filter being capable of passing only radiation having a predetermined range of wavelengths. 
     
     
         30 . The medical thermometer of  claim 29 , wherein the filter is capable of passing only radiation having wavelengths between about 7.5 μm and about 13.5 μm. 
     
     
         31 . The medical thermometer of  claim 29 , wherein the filter is a component of a radiation sensor assembly which includes the radiation sensor. 
     
     
         32 . A medical thermometer, comprising:
 a parabolic mirror defined by the equation y=ax 2 +bx+c, where a is between approximately 0.07 and 0.09, b is between approximately −0.02 and −0.01, the parabolic mirror having an axis of symmetry, a vertex, a baseline tangent to the mirror at the vertex, and a focal point; and   a radiation sensor having a center point on a detection surface, the center point being disposed at the focal point and the normal to the detection surface being oriented between 30° and 33° from the baseline, such that the sensor is configured to detect radiation reflected by the mirror.   
     
     
         33 . The medical thermometer of  claim 32  further including a radiation entrance such that the mirror is configured to reflect away from the radiation sensor radiation that passes through the radiation entrance and that is not oriented between approximately −5° and 5° from the axis of symmetry. 
     
     
         34 . A method of using a medical thermometer including a housing having radiation entrance, a mirror having an axis disposed in the housing, and a radiation sensor, comprising:
 disposing the thermometer relative to a target; and   directing the radiation entrance toward the target,   wherein radiation that passes through the radiation entrance and that is oriented outside a radiation range of angles from the axis is reflected away from the radiation sensor by the mirror.   
     
     
         35 . The method of  claim 34  wherein the mirror has a parabolic shape as defined by the equation y=ax 2 +bx+c, where a is not equal to 0, the parabolic shape having a focal point, a vertex, and an axis of symmetry collinear with the axis of the mirror. 
     
     
         36 . The method of  claim 35  wherein a is between approximately 0.07 and 0.09. 
     
     
         37 . The method of  claim 36  wherein b is between approximately −0.02 and −0.01. 
     
     
         38 . The method of  claim 34  wherein the radiation sensor includes a detection surface having a center point thereon and wherein the center point is disposed approximately at the focal point. 
     
     
         39 . The method of  claim 34  wherein the radiation range of angles from the axis is from approximately −5° to 5°.