High speed infrared radiation thermometer, system, and method The results of both the ongoing 2-year study and the 5-month instrument comparison show that IR thermometers can measure PW with an accuracy (rms difference/mean PW) approaching 10%, the accuracy typically ascribed to sun photometers. The best results of this comparison were provided by two IR thermometers models that yielded an r2 of 0.96 and an rms difference with the PW of 2.7 mm. An expanded study compared Tz from eight IR thermometers with PW at various times during the day and night from 17 May to 18 October 2010, mainly at the Texas site and 10 days at Hawaii's Mauna Loa Observatory (MLO). A comparison of the Tz data with the PW provided by a GPS site 31 km NNE yielded an r2 of 0.79, and an rms difference of 5.8 mm. The coefficient of correlation (r2) of the PW and Tz was 0.90, and the rms difference was 3.2 mm. PW was measured by a MICROTOPS II sun photometer. Brooks, David R.Ī 2-year study affirms that the temperature (Tz) indicated by an inexpensive ($20 to $60) IR thermometer pointed at the cloud-free zenith sky provides an approximate indication of the total column water vapor (precipitable water or PW). Measuring Total Column Water Vapor by Pointing an Infrared Thermometer at the Sky Additionally, the difference between true temperature and output of the IR thermometer for a reference plate was compared to that obtained for vegetation, and the RMS obtained was Calibration for sky radiant emittance was improved by using the difference between sky radiant temperature and air temperature.When the surface temperature measured by the infrared thermometer is plotted against the surface temperature measured by thermocouple, the sky radiant emittance error is obtained from the Y intercept. The measurement error becomes larger at emissivity settings under 0.7.The measurement error outdoors was not proportional to the downward longwave radiation, but to the sky radiant temperature measured by the IR thermometer. Measurement accuracy is improved with a controlled internal temperature of 20-30Â☌. (5) Calibration method for the terrestrial surface.The following is a summary of the results: Measurement error is affected by the internal temperature of the IR thermometer. (4) Effect of sky radiant emittance on the measured surface temperature. (3) Response of the output signal to changes in the emissivity setting. (2) Linearity of the output signal of the IR thermometer. Experiments were performed with regard to the following items: (1) Measurement errors related to the internal temperature of the IR thermometer. If, therefore, there is a large difference between the internal temperature of the IR thermometer and the apparent temperature associated with the surrounding radiation, a large error will be induced into the measured surface temperature.The purpose of our research was to determine the characteristics and measurement errors of IR thermometers. The characteristics of the IR thermometer, however, are not well known.IR thermometers manufactured in Japan systematically adjust for ambient radiation based on the internal temperature of the thermometer. Infrared thermometers to measure surface temperature have been increasingly adopted in recent years. International Nuclear Information System (INIS) Characteristics of infrared thermometers manufactured in Japan and calibration methods for sky radiant emittance
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