Clinical hand-held infrared thermometer with special optical configuration

An apparatus adapted to be held in a user's hand for measuring, from a range of measurement distances from a surface, the temperature of a measured area of the surface, the apparatus comprising:

• a main housing having a main aperture partially defining an apparatus field of view;
• a detector within the main housing and having a sensitive area for detecting infrared energy entering the main housing via the main aperture;
• means within the main housing for generating at a distance from the main aperture an optical image of the sensitive area having substantially the same shape as the sensitive area;
• and
• a limiting aperture defined within the main housing between the main aperture and the generating means, and having approximately the same size and shape as the optical image, there being defined axially between the optical image and the limiting aperture an imaginary column having a lateral size corresponding generally to the size of the optical image;
• wherein infrared energy originating at the surface within the column passes through the limiting aperture to strike the sensitive area, and the limiting aperture prevents infrared energy not originating at the surface within the column from striking the sensitive area, whereby a size of the measured area of the surface remains approximately constant notwithstanding changes in the field of view.

A hand-held clinical thermometer for measuring the temperature of a measured area on a surface of patient's skin without contacting the surface with the thermometer, the thermometer comprising:

• a main housing having a main aperture;
• an infrared light detector within the housing and having a sensitive area for detecting infrared energy entering the housing via the main aperture;
• means within the housing for generating, at an image distance from the main aperture, an optical image of the detector's sensitive area having substantially the same shape as the sensitive area;
• and
• a limiting aperture defined within the main housing between the main aperture and the generating means, and having approximately the same size and shape as the optical image;
• wherein when the main aperture is held at a measurement distance from the measured area, the measured area is approximately equal in size and shape to the optical image, the measurement distance being within a predetermined range of effective distances equal to or less than the image distance;
• wherein the limiting aperture prevents infrared energy not originating at the measured area from striking the detector's sensitive area, whereby the infrared energy flux from the measured area and detected by the detector remains constant despite variances in the field of view due to changes in the measurement distance.

A method for measuring, at a measurement distance from a surface, the temperature of a measured area of the surface, the method comprising:

• defining, with a main aperture in a housing, a field of view;
• measuring with a detector the infrared energy entering the housing via the main aperture;
• limiting with optical means including a limiting aperture the infrared energy that strikes the detector;
• displaying with an LCD display viewable on the exterior of the housing a visual readout of a measurement result;
• preventing, with the limiting aperture, infrared energy not originating at the measured area of the surface from striking the detector;
• measuring energy emitted from the measured area by scanning the measured area by moving the thermometer relative to the surface;
• and
• integrating mathematically any non-uniform infrared energy measurements by the detector from the measured area during a period of time;
• whereby the field of view is variable according to the measurement distance between the measured surface and the main aperture, while the measured area is substantially constant in size independent of the measurement distance.