Radiation detector with temperature display

Abstract

A radiation detector with temperature readout has a multicolored LED display divided into segments of zero degrees to 9 degrees centigrade colored green, 10 degrees to 19 degrees centigrade in yellow, and 20 degrees to 100 degrees centigrade in red. Alternatively, two red segments are provided for ranges of 20 degrees to 64 degrees centigrade and 65 degrees centigrade and above, respectively. The radiation detector is automatically zeroed at ambient upon use and provides a readout of temperature rise above ambient throughout a scan of a subject. In one design, only one LED for each segment of the display is illuminated at a time. An audible signal is sounded at an increasing pulse frequency as the display is illuminated from the green segment to the red segment of measured temperature rise above ambient with a constant tone for temperature rises above about 20 degrees centigrade. In an alternative design a timing circuit allows the detector to self operate for a predetermined length of time. The detector sounds a `beep` tone before automatically shutting itself off. A window made of germanium covers the radiation sensor and filters out wavelengths not of interest.

We claim: 
     
       1. A radiation detector comprising: a radiation sensor;   a display assembly means responsive to a reference temperature signal and .[.sinals.]. .Iadd.signals .Iaddend.indicative of radiation levels detected by the sensor for providing on a display an indication of the temperature of a subject above a reference temperature; and   a timing circuit means which maintains the detector in operation for a predetermined length of time and thereafter automatically shuts off the detector, said reference temperature signal being reset when the detector is turned on subsequent to its automatically shutting off, said timing circuit means comprising:   a counter;   a power switch by which a user initially connects a battery to said counter and means for establishing the reference temperature signal;   an internal switch which is closed after the battery is connected to said counter and means for establishing the reference temperature signal, said internal switch closed maintaining the connection of the battery to circuits of the detector thereby allowing a user to release the power switch and the detector to maintain itself in operation, state of said internal switch being dependent on an output signal from said timing circuit means; and   means for producing an audible signal dependent on a control signal from said counter and a second output signal from said timing circuit means, said audible signal sounding when said counter reaches a predetermined count and, said timing circuit means thereafter turns off the detector by opening the internal switch.   
     
     
       2. A radiation detector as claimed in claim 1 wherein said display is arranged in segments of different colors. 
     
     
       3. A radiation detector as claimed in claim 2 wherein the colors of said segments are green, yellow and red, respectively. 
     
     
       4. A radiation detector as claimed in claim 1 wherein said display has segments arranged to indicate temperature from about zero degrees centigrade to about 9 degrees centigrade, about 10 degrees to about 19 degrees centigrade, and about 20 degrees centigrade and greater, respectively. 
     
     
       5. A radiation detector as claimed in claim 1 wherein, the means for producing an audible signal includes means producing an audible signal having a pulse frequency that increases in correspondence with each temperature increase detected by the sensor and indicated in the display, the means being associated with the signals indicative of detected radiation. 
     
     
       6. A radiation detector as claimed in claim 1 further comprising an autozero circuit which establishes the reference temperature signal which is summed with said signal indicative of detected radiation to produce a display signal, the autozero circuit comprising means for establishing the reference temperature signal indicative of ambient temperature and means for holding the reference signal, the display assembly means being responsive to the display signal. 
     
     
       7. A radiation detector as claimed in claim 6 wherein said reference temperature signal is established by placing a voltage on a capacitor. 
     
     
       8. A radiation detector as claimed in claim 1 further comprising a window, the window covering said sensor to filter out short wavelengths on the order of less than about 1.5 microns while allowing longer wavelengths of about 1.5 to 3 microns and greater to be detected by said sensor. 
     
     
       9. A radiation detector as claimed in claim 8 wherein the window comprises germanium. 
     
     
       10. A radiation detector comprising: a radiation sensor providing a radiation signal indicative of sensed radiation;   an autozero circuit which establishes a reference signal which is summed by summing means with the radiation signal from the radiation sensor to provide a display signal;   a display assembly responsive to the display signal and having a multicolor display for providing a visual indication of the amount of radiation sensed by the radiation sensor, the display arranged in segments of different colors;   a sound generator means for generating an audible signal with differing pulse frequencies, each pulse frequency corresponding to an amount of radiation indicated by the display such that the pulse frequency increases for increasing amount of radiation indicated on the display   means for filtering out short wavelengths on the order of less than about 1.5 microns while allowing longer wavelengths above about 1.5 microns generated by sources of interest to be sensed by the sensor; and   a timing circuit initialized when power is applied to the detector and which maintains power supply to circuits of the detector for a predetermined length of time through control of an internal power switch means and thereafter automatically shuts off the detector by applying a control signal to the internal power switch means and a signal to actuate the sound generator means prior to shut-off of the detector, said reference signal being reset when the detector is turned on subsequent to its automatically shutting off.   
     
     
       11. A radiation detector comprising: a radiation sensor;   a display assembly means for providing on a segmented illuminatable display .[.in.]. .Iadd.an .Iaddend.indication of the amount of radiation sensed by the radiation sensor above a reference amount of radiation;   an autozero circuit comprising time controlled means for .Iadd.placing a voltage on a capacitor for .Iaddend.establishing a reference signal indicative of a reference amount of radiation detected by the radiation .[.sensor; and.]. .Iadd.sensor from a reference target;   means for summing .Iaddend.the reference signal .[.being summed.]. with a radiation signal indicative of the amount of sensed radiation subsequently detected by the radiation sensor to provide a display signal, the display assembly .Iadd.means .Iaddend.being responsive to the display signal and thereby providing on the display an indication of the amount of .[.a.]. radiation sensed above the reference amount of radiation; .Iadd.and .Iaddend.timing means for controlling the time controlled means. .[.   
     
     
       12.  A radiation detector as claimed in claim 11 wherein said time controlled means for establishing a reference signal includes placing a voltage on a capacitor, the voltage being produced by the radiation sensor initially detecting a reference target..]. 
     
     
       13. A radiation detector as claimed in claim .[.11.]. .Iadd.12 .Iaddend.wherein said .[.means for controlling said time controlled means comprise.]. .Iadd.timing means comprises .Iaddend.a timer coupled to .[.a switch.]. .Iadd.the time controlled means .Iaddend.which enables .Iadd.a .Iaddend.reference signal voltage to be placed on the capacitor for a certain amount of time after initial detection of an ambient target and thereafter disables the placing of said reference signal voltage on the capacitor, after the certain amount of time the timer providing an output voltage drop which enables the display assembly means to illuminate one segment of the display signifying to a user that the detector has been autozeroed. 
     
     
       14. A radiation detector as claimed in claim 13 further comprising means for producing an audible signal which corresponds to the amount of radiation sensed by the sensor .[.and.]. .Iadd.above an ambient level which is .Iaddend.indicated on the display, a pulse frequency of the audible signal increasing for each increase in amount of sensed radiation indicated by the display, .[.where.]. .Iadd.wherein .Iaddend.the timer disables the audible signal producing means .[.from.]. .Iadd.to inhibit the .Iaddend.sounding .Iadd.of .Iaddend.the audible signal during the time in which reference signal voltage is placed on the capacitor and enables the audible signal producing means to sound the audible signal thereafter when the display in illuminated. 
     
     
       15. A radiation detector as claimed in claim 14 wherein the means for producing an audible signal includes a buzzer which is disabled and enabled by a switch controlled by the user. 
     
     
       16. A radiation detector as claimed in claim 11 further comprising.Iadd.: .Iaddend. means for producing an audible signal having a pulse frequency that increases for each increase in amount of sensed radiation indicated by the display.[., the.]..Iadd.; and .Iaddend.   means for .[.producing.]. .Iadd.disabling production of .Iaddend.the audible signal .[.being disabled by said timing means.]. during the time in which the reference signal is established.Iadd., .Iaddend.and .[.enabled thereafter.]. .Iadd.for enabling production of the audible signal after the reference signal is established.Iaddend..   
     
     
       17. A radiation detector as claimed in claim 16 wherein the means for producing an audible signal includes a buzzer which is enabled and disabled by a switch controlled by a user. 
     
     
       18. A radiation detector as claimed in claim 11 wherein the display includes: a green LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures slightly above the temperature corresponding to the reference amount of radiation;   a yellow LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures higher above the temperature corresponding to the reference amount of radiation than the range of the green LED; and   a first red LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures higher above the temperature corresponding to the reference amount of radiation than the range of the yellow LED, and wherein only one LED is illuminated at a time.   
     
     
       19. A radiation detector as claimed in claim 18 further comprising a second red LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures higher above the temperature corresponding to the reference amount of radiation than the range of the first red LED, and wherein the first red LED indicates a range of temperatures of about 20 degrees to 64 degrees centrigrade above the temperature corresponding to the reference amount of radiation and the second red LED indicates a range of temperatures of about 65 degrees centigrade and greater above the temperature corresponding to the reference amount of radiation. 
     
     
       20. A radiation detector as claimed in claim 11 further comprising a window, the window covering said sensor to filter out short wavelengths on the order of less than about 1.5 microns while allowing longer wavelengths of about 1.5 to 3 microns and greater to be detected by said sensor. 
     
     
       21. A radiation detector as claimed in claim 20 wherein the window comprises germanium. 
     
     
       22. A radiation detector comprising: a radiation sensor;   an autozero circuit means which establishes a reference signal and subtracts it from a radiation signal indicative of sensed radiation to provide a display signal, the autozero circuit means comprising a time controlled switch which enables voltage being produced by the radiation sensor initially detecting a reference target at ambient temperature to be placed on a capacitor for a certain amount of time after initial detection of ambient temperature and thereafter disables the placing of voltage on the capacitor, the voltage charging the capacitor to a level indicative of detected ambient temperature such that the charged capacitor provides a reference signal corresponding to .Iadd.the .Iaddend.ambient temperature;   a selectively actuated display assembly having a display of different colored LED's, the assembly being responsive to the display signal to drive the display to provide an indication of the amount of radiation sensed by the radiation sensor as a difference between the reference signal and the radiation signal .Iadd.and to be .Iaddend.indicative of the sensed radiation, one LED of the display being initially illuminated when the time controlled switch disables the placing of voltage on the capacitor signifying to a user that the detector has been autozeroed;   a means for controlling said time controlled switch and selectively actuating said display assembly, and a means for producing an audible signal;   said audible signal .[.corresponds.]. .Iadd.corresponding .Iaddend.to each LED such that the pulse frequency of the audible signal increases for each temperature increase of sensed radiation indicated within each LED and continues to increase for each temperature increase of sensed radiation indicated from one LED to the next; and   means for filtering out short wavelengths on the order of less than about 1.5 microns while allowing longer wavelengths generated by sources of interest to be sensed by the sensor.   
     
     
       23. A radiation detector as claimed in claim 22 wherein said means for producing an audible signal limits the pulse frequency such that the audible signal is at a constant tone for sensed temperature increase above 20 degrees centigrade. 
     
     
       24. A radiation detector as claimed in claim 22 wherein said display includes: a green LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures slightly above the detected ambient temperature;   a yellow LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures higher above the detected ambient temperature than the range of the green LED; and   a first red LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures higher above the detected ambient temperature than the range of the yellow LED, and wherein only one LED is illuminated at a time.   
     
     
       25. A radiation detector as claimed in claim 24 further comprising a second red LED for indicating the detection of an amount of radiation which has a corresponding temperature within a range of temperatures higher above the detected ambient temperature than the range of the first red LED. 
     
     
       26. A radiation detector comprising: a radiation sensor;   a display assembly .Iadd.means .Iaddend.associated with the sensor for providing on a display a temperature indication, relative to an ambient temperature, .Iadd.of .Iaddend.the amount of radiation sensed by the radiation sensor, the display being accurate for radiation amounts corresponding to temperatures above the ambient temperature about 100° C. and lower;   means for filtering out short wavelengths on the order of less than about 1.5 microns while allowing longer wavelengths in a range about 1.5 to 3 microns and greater generated by sources of interest to be sensed by said sensor; and   a housing for holding the sensor, display assembly .Iadd.means.Iaddend., display and means for filtering, the housing being of dimensions enabling hand held usage of the detector.   
     
     
       27. A radiation detector as claimed in claim 26 wherein said means for filtering is a window comprising germanium, the window covering said sensor. 
     
     
       28. A radiation sensor as claimed in claim 26 wherein said means for filtering out short wavelengths filters out wavelengths of reflected sun light and other visible light. 
     
     
       29. A method of sensing radiation, the steps comprising: zeroing a radiation detector by detecting with the detector radiation indicative of an ambient temperature;   scanning a target area with the radiation detector, the detector having a display and an audible signal indicative of sensed temperature difference between a temperature corresponding to an amount of detected radiation during the scanning and the previously detected ambient temperature;   locating a subject within the target area by noting the subject at which the detector is pointing when the audible signal reaches a certain state; and   providing a quantitative indication of temperature difference between the ambient temperature and temperature of the located subject using the display of the radiation detector.   
     
     
       30. A method as claimed in claim 29 further comprising the step of filtering out short wavelengths on the order of less than about 1.5 microns while allowing longer wavelengths of interest to be sensed by the radiation detector. 
     
     
       31. A method as claimed in claim 29 wherein the step of providing a quantitative indication includes providing a bar graph display of the temperature difference. 
     
     
       32. A radiation detector comprising: a housing adapted to be hand held during use of the detector;   a radiation sensor positioned in the housing for sensing radiation received through one end of the housing;   a display assembly means having a display on the housing, the assembly means being responsive to the sensed radiation and driving the display to provide a temperature indication relative to the amount of radiation sensed by the radiation sensor; and   filtering means for substantially filtering out wavelengths of energy generated from sunlight while passing wavelengths generated by sources of interest and for substantially allowing wavelengths of energy from a flame about 1100° to about 1370° C. to be sensed by the sensor such that a relative temperature indication thereof is provided on the display, the display only providing .[.accurate.]. temperature indications up to temperatures substantially less than that of the flame.   
     
     
       33. A radiation detector comprising: a radiation sensor;   means for establishing a reference signal indicative of a reference temperature when the detector is turned on;   a display assembly means responsive to said reference signal and signals of the sensor indicative of sensed radiation for providing on a display an indication of the temperature of a subject above said reference temperature;   a timing circuit means which maintains the detector in operation for a predetermined length of time and thereafter automatically shuts off the detector and provides an actuating signal to a means for producing an audible signal, said reference temperature being reestablished when the detector is turned on subsequent to its automatically shutting off;   said means for producing an audible signal having a pulse frequency that increases in correspondence with each temperature increase detected by the sensor and indicated in the display, said audible signal further sounding just once before the automatic turning off of the detector in response to a signal from said timing circuit means. .[.   
     
     
       34.  A radiation detector comprising: a radiation sensor;   an autozero circuit means for establishing a reference signal indicative of a reference temperature when the detector is turned on   a display assembly means responsive to signals indicative of radiation levels detected by the sensor for providing on a display an indication of the temperature of a subject above said reference temperature;   a timing circuit means which maintains the detector in operation for a predetermined length of time and thereafter automatically shuts off the detector, said reference signal being reestablished when the detector is turned on subsequent to its automatically shutting off; and   said autozero circuit means establishes said reference signal and sums it with a radiation signal indicative of sensed radiation to produce a display signal the autozero circuit means further comprising means for holding the reference signal, said reference signal being reestablished by placing a voltage on a capacitor..]..Iadd.   
     
     
       35.  A radiation detector as claimed in claim 32 wherein said filtering means blocks wavelengths of about 1.5 microns and less..Iaddend..Iadd.36. A radiation detector as claimed in claim 32 further comprising sound generator means for producing an audible signal having a pulse frequency that increases in correspondence with increases in temperature detected by 
     
     
        the sensor and indicated in the display..Iaddend..Iadd.37.  A radiation detector as claimed in claim 32 wherein said display assembly means comprises a bar graph display comprising red, yellow, and green groups of light indicators, the light indicators representing incremental 
     
     
        temperature differences..Iaddend..Iadd.38.  A radiation detector as claimed in claim 32 wherein the display assembly means comprises a green LED for indicating temperature from about zero degrees centigrade to about 10 degrees centigrade, a yellow LED for indicating temperature from about 10 degrees centigrade to about 20 degrees centrigrade, and a first red LED for indicating temperature from about 20 degrees centigrade and greater 
     
     
        and wherein only one LED is illuminated at a time..Iaddend..Iadd.39.  A radiation detector as claimed in claim 38 wherein the first red LED indicates temperature from about 20 degrees centrigrade to about 65 degrees centigrade, the display assembly further comprising a second red LED for indicating temperature from about 65 degrees centigrade and 
     
     
        greater..Iaddend..Iadd.40.  A radiation detector as claimed in claim 32 wherein said detector is adapted to detect temperature variations of electrical equipment..Iaddend..Iadd.41. A radiation detector as claimed in 
     
     
        claim 32 wherein the filtering means comprises a lens..Iaddend..Iadd.42. A method of sensing radiation, the steps comprising: zeroing a radiation detector by detecting with the detector radiation indicative of an ambient temperature;   scanning a target area with the radiation detector, the detector having an audible signal a frequency of which is indicative of sensed temperature differences between a temperature corresponding to an amount of detected radiation during the scanning and the previously detected ambient temperature;   locating a subject within the target area by the frequency of the audible signal; and   providing a quantitative indication of temperature of the located subject   
     
     
        using a display of the radiation detector..Iaddend..Iadd.43.  A method as claimed in claim 42 further comprising the step of filtering out short wavelengths of less than about 1.5 microns while allowing longer wavelengths of interest to be sensed by the radiation detector..Iaddend..Iadd.44. A method as claimed in claim 42 wherein the step of providing a quantitative indication includes providing a display of the temperature with colors indicating different 
     
     
        temperatures..Iaddend..Iadd.45.  A method as claimed in claim 42 wherein the scanning step includes scanning a target area of electrical equipment 
     
     
        with the radiation detector..Iaddend..Iadd.46.  A radiation detector adapted for scanning a target area comprising: a radiation sensor providing a radiation signal indicative of sensed radiation;   a display means for providing a quantitative indication of a sensed temperature difference;   a circuit means responsive to the radiation sensor for zeroing the radiation detector by establishing a reference signal indicative of an ambient temperature and for driving the display means to provide the quantitative indication of the sensed temperature difference between a temperature corresponding to an amount of sensed radiation during scanning of the target area, which is higher than the ambient temperature, and the reference signal indicative of the ambient temperature;   a sound generator means responsive to the radiation sensor and circuit means for generating an audible signal indicative of sensed temperature difference between a temperature corresponding to an amount of sensed radiation during scanning of the target area and the reference signal   
     
     
        indicative of an ambient temperature..Iaddend..Iadd.47.  A radiation detector as claimed in claim 46 wherein said display means comprises segments of different colors for providing a visual indication of sensed 
     
     
        radiation relative to ambient temperature. .Iaddend..Iadd.48.  A radiation detector as claimed in claim 46 wherein the display means comprises a green LED for indicating temperature from about zero degrees centigrade to about 10 degrees centigrade above ambient temperature, and a first red LED for indicating temperature from about 20 degrees centigrade above ambient temperature and greater and wherein only one LED is illuminated at a time. 
     
     
        .Iaddend..Iadd.49.  A radiation detector as claimed in claim 48 wherein the first red LED indicates temperature from about 20 degrees centigrade to about 65 degrees centigrade above ambient temperature, the display assembly further comprising a second red LED for indicating temperature from about 65 degrees centigrade above ambient temperature and greater. 
     
     
        .Iaddend..Iadd.50.  A radiation detector as claimed in claim 46 further comprising filtering means for substantially filtering out wavelengths of energy generated from sunlight while passing wavelengths generated by a flame at about 1100° C. to about 1370° C. .Iaddend..Iadd.51. A radiation detector as claimed in claim 50 wherein said filtering means is a long wave pass filter which starts passing light at wavelengths in 
     
     
        the range of about 1.5 microns to 3.0 microns. .Iaddend..Iadd.52.  A radiation detector comprises: a radiation sensor providing a radiation signal indicative of sensed radiation;   an autozero circuit means which establishes a reference signal;   means for combining the reference signal with said radiation signal to provide a temperature difference signal;   sound generator means for producing an audible signal responsive to the temperature difference signal; and   a display assembly means responsive to the temperature difference signal and having a multicolor display for providing a visual indication of the temperature difference signal, wherein the display comprises a green LED for indicating temperature from about zero degrees centigrade to about 10 degrees centigrade, a yellow LED for indicating temperature from about 20 degrees centigrade to about 20 degrees centigrade, and a first red LED for indicating temperature from about 20 degrees centigrade and greater and   
     
     
        wherein only one LED is illuminated at a time. .Iaddend..Iadd.53.  A radiation detector as claimed in claim 52 wherein the first red LED indicates temperature from about 20 degrees centigrade to about 65 degrees centigrade, the display assembly further comprising a second red LED for indicating temperature from about 65 degrees centigrade and greater. 
     
     
        .Iaddend..Iadd.54.  A radiation detector as claimed in claim 52 wherein said detector is adapted to sense radiation from electrical equipment. 
     
     
        .Iaddend..Iadd.55.  A radiation detector as claimed in claim 52 wherein the sound generator means produces an audible signal having a pulse frequency that increases in correspondence with increasing temperature 
     
     
        detected by the sensor and indicated by the display. .Iaddend..Iadd.56.  A radiation detector as claimed in claim 52 further comprising means for housing the radiation detector, said housing means having an opening, the radiation sensor being positioned in the housing means to sense radiation passing through the opening, the housing being adapted to be hand held 
     
     
        during use of the detector. .Iaddend..Iadd.57.  A radiation detector as claimed in claim 52 further comprising filtering means for substantially filtering out wavelengths of energy generated from sunlight while passing wavelengths generated by a flame at about 1100° C. to about 1370° C. .Iaddend..Iadd.58. A radiation detector as claimed in claim 57 wherein said filtering means is a long wave pass filter which starts passing light at wavelengths in the range of about 1.5 microns to 
     
     
        3.0 microns. .Iaddend..Iadd.59.  A radiation detector as claimed in claim 57 comprising a lens through which radiation is received by the radiation 
     
     
        sensor. .Iaddend..Iadd.60.  A radiation detector adapted for scanning of a target area comprising: a housing adapted to be hand held during the use of a detector;   a radiation sensor positioned in the housing for sensing radiation received through one end of the housing and generating a radiation signal indicating levels of the radiation;   a circuit for generating a reference signal from the radiation signal indicative of ambient radiation levels;   a multicolor display means for providing a visual quantitative indication of a difference signal in green, yellow and red segments of an LED display;   a filtering means for substantially filtering out wavelengths of radiation energy generated from sunlight while passing wavelengths of radiation energy generated by sources of a flame at about 1100° to about 1370° C.;   sound generator means for producing an audible signal having a pulse frequency that increases with increasing radiation sensed by the radiation sensor and indicated by the display means; and   an amplifier for driving the multicolor display means and the sound generator means and for generating the difference signal in response to   
     
     
        the reference signal and the radiation signal. .Iaddend..Iadd.61.  A radiation detector as claimed in claim 60 wherein said filtering means is a long wave pass filter which starts passing light at wavelengths in the range of about 1.5 microns and greater generated by sources of interest. .Iaddend..Iadd.62. A radiation detector as claimed in claim 60 wherein the 
     
     
        filtering means comprises a lens. .Iaddend..Iadd.63.  A radiation detector adapted for scanning of a target area comprising: a housing adapted to be hand held during the use of a detector;   a radiation sensor positioned in the housing for sensing radiation received through one end of the housing;   a multicolor display means for providing a visual indication of the radiation sensed by the sensor in green, yellow and red segments of an LED display, the display means comprising a green LED for indicating temperature, corresponding to sensed radiation, from about zero degrees centigrade to about 10 degrees centigrade, a yellow LED for indicating temperature, corresponding to sensed radiation, from about 10 degrees centigrade to about 20 degrees centigrade, and a first red LED for indicating temperature, corresponding to sensed radiation, from about 20 degrees centigrade and greater, only one LED being illuminated at a time;   a driver for driving the multicolored display means in response to the sensor; and   a filtering means for substantially filtering out wavelengths of radiation energy generated from sunlight while passing wavelengths of radiation energy generated by sources of a flame at about 2000° to about   
     
     
        2500° F. .Iaddend..Iadd.64.  A radiation detector as claimed in claim 63 wherein the first red LED indicates temperature from about 20 degrees centigrade to about 65 degrees centigrade, the display means further comprising a second red LED for indicating temperature, corresponding to sensed radiation, from about 65 degrees centigrade and 
     
     
        greater. .Iaddend..Iadd.65.  A radiation detector adapted for scanning of a target area of electrical equipment comprising: a radiation sensor for sensing radiation during scanning of the target area;   a circuit for establishing a reference signal indicative of a reference amount of radiation detected by the radiation sensor;   means for providing an indication of the amount of radiation sensed by the sensor above the reference amount of radiation, the means for providing an indication comprising sound generator means for producing an audible signal having a pulse frequency that increases with increasing radiation detected by the radiation sensor; and   a filtering means for substantially filtering out wavelengths of radiation energy generated from sunlight while passing wavelengths of radiation energy generated by a flame at about 1100° C. to about 1370°   
     
     
        C. .Iaddend..Iadd.66.  A radiation detector adapted for scanning of a target area of electrical equipment comprising: a radiation sensor for sensing radiation during scanning of the target area and generating a radiation signal;   a circuit means for establishing a reference signal being indicative of a reference amount of radiation detected by the radiation sensor and comparing the reference signal to the radiation signal;   display means responsive to the circuit means for providing an indication of the amount of radiation sensed by the sensor above the reference amount of radiation for radiation corresponding to temperatures less then 100° C., the display means comprising segments colored green, yellow and red respectively, wherein only one segment is illuminated at a time; and   a filtering means for substantially filtering out wavelengths of radiation energy in sunlight from passing to the sensor while passing to the sensor wavelengths of radiation energy generate by a flame at about 1100°   
     
     
        C. to about 1370° C. .Iaddend..Iadd.67.  A radiation detector as claimed in claim 66 wherein the means for providing an indication is a display which comprises a green LED for indicating temperature from about zero degrees centigrade to about 10 degrees centigrade, a yellow LED for indicating temperature from about 10 degrees centigrade to about 20 degrees centigrade, and a first red LE for indicating temperature from about 20 degrees centigrade and greater and wherein only one LED is illuminated at a time. .Iaddend..Iadd.68. A radiation detector as claimed in claim 67 wherein the first red LED indicates temperature from about 20 degrees centigrade to about 65 degrees centigrade, the display assembly further comprising a second red LED for indicating temperature from about 
     
     
        65 degrees centigrade and greater. .Iaddend..Iadd.69.  A radiation detector comprising: a housing adapted to be hand-held during use of the detector;   a radiation sensor positioned in the housing for sensing radiation from a target through one end of the housing and generating a sensor signal indicative of the sensed radiation;   an autozero circuits which establishes a reference signal indicative of an ambient temperature in response to the sensor signal received by the radiation sensor; and   an amplifier that drives a sound generator means responsive to the radiation sensor and the reference signal for producing an audible signal having a pulse frequency that increases with increase in temperature of   
     
     
        the target. .Iaddend..Iadd.70.  A radiation detector comprising: a radiation sensor generating a radiation signal indicative of sensed radiation;   an autozero circuit means responsive to the radiation sensor for automatically establishing a reference signal indicative of a reference temperature when the detector is turned on, said autozero circuit means summing said reference signal with said radiation signal to produce a display signal;   a display assembly means responsive to the display signal for providing on a display an indication of the temperature of a subject above said reference temperature; and   a timing circuit means which maintains the detector in operation for a predetermined length of time and thereafter automatically shuts off the detector, said reference signal being reestablished when the detector is turned on subsequent to its automatically shutting off.   
     
     
        .Iaddend..Iadd.     A radiation detector comprising: a radiation sensor;   means responsive to the sensor for generating a reference signal indicating radiation levels;   a bar graph display providing a visible temperature indication at temperatures substantially less than a flame;   an amplifier for driving the display in response to an amount of radiation sensed by the radiation sensor and the reference signal;   a filter attenuating short wavelengths on the order of less than about 1.5 microns while allowing longer wavelengths in a range above about 1.5 to 3 microns and greater generated by sources of interest to be sensed by the radiation sensor; and   a housing having an opening for enabling entrance of radiation, the filter being supported by the housing to filter the radiation and the sensor being supported by the housing to detect the radiation filtered by the filter, the display being supported by the housing to present its visible temperature indication, the housing being of dimensions enabling hand held   
     
     
        usage of the detector. .Iaddend..Iadd.72.  A radiation detector as claimed in claim 71 wherein the filter attenuates wavelengths of reflected 
     
     
        sunlight and other visible light. .Iaddend..Iadd.73.  A radiation detecting device, comprising: a radiation sensor generating a detected radiation signal in response to received radiation;   a filter, in front of the radiation sensor, attenuating short wavelengths of radiation contained in sunlight and substantially passing wavelengths of radiation associated with a flame about 2000° to about 2500° F. and wavelengths of radiation associated with temperatures substantially less than the flame;   a bar graph display indicating temperatures substantially less than the flame; and   a circuit generating a comparison of the detected radiation signal and an ambient radiation signal representing an ambient level of radiation and   
     
     
        driving the display in response to the comparison. .Iaddend..Iadd.74.  A radiation detecting device as claimed in claim 73, wherein the bar graph display comprises a multicolor bar graph for providing a visible indication of a temperature above an ambient temperature of a target at 
     
     
        which the radiation sensor is directed. .Iaddend..Iadd.75.  A radiation detecting device as claimed in claim 73, wherein the filter blocks wavelengths of about 1.5 microns and less. .Iaddend..Iadd.76. A radiation detecting device as claimed in claim 73, wherein the filter comprises a 
     
     
        germanium lens. .Iaddend..Iadd.77.  A method for identifying electrical equipment operating temperature, the method comprising: determining an ambient level of radiation with a radiation sensor;   scanning a target area comprising electrical equipment with the radiation sensor;   filtering radiation from the target area to the radiation sensor by attenuating short wavelengths of radiation of less than about 1.5 microns and substantially passing wavelengths between 1.7 and 3 microns and greater including wavelengths emitted by electrical equipment at less than 100° C.;   detecting the filtered radiation with the radiation sensor;   displaying a visible indication of operating temperature corresponding to an amount of the detected filtered radiation above a level corresponding   
     
     
        to the ambient level of radiation. .Iaddend..Iadd.78.  A method as claimed in claim 77, wherein displaying the visible indication comprises driving a multicolor bar graph providing the visible indication in response to the detected radiation. .Iaddend..Iadd.79. A method as claim in claim 77, further comprising identifying electrical equipment exhibiting an aberrant temperature in response to the detected radiation exceeding the level corresponding the ambient level of radiation by a predetermined amount. .Iaddend.