AC-Mode Short-Wavelength IR Radiation Thermometers for Measurement of Ambient Temperatures
- 82 Downloads
Recent improvements in the fabrication of short-wave infrared (SW-IR) quantum detectors have opened a new era in radiation thermometry. Ambient and higher temperatures can be measured with low uncertainties using thermoelectrically (TE) cooled extended-InGaAs (E-IGA) and short-wave photovoltaic-HgCdTe (SW-MCT) detectors. Since these detectors have low cut-off wavelengths (2.5 μm and 2.8 μm, respectively), they do not respond past cut-off and are less sensitive to the background infrared radiation, resulting in orders of magnitude lower background noise than traditional broad-band infrared detectors such as cryogenically cooled quantum detectors or thermal detectors. At the same time, the cut-off is far enough in the infrared to obtain a large enough signal from the source of interest. Because of the low detector cut-off wavelength, traditional glass-based optics can be used in the radiation thermometers. A chopper-produced alternating-current (AC) signal was used to measure low temperatures by separating the AC signal from the background-radiation-produced direct-current (DC) signal and its fluctuations. Design considerations and characteristics of a newly developed SW-IR radiation thermometer are discussed. A noise-equivalent temperature difference (NETD) of < 3mK for a 50°C blackbody was measured. At the human body temperature of 36°C, the obtained NETD of ~10mK indicates that these detectors can be used in non-contact temperature measurements to replace thermopile- or pyroelectric-based radiation thermometers.
KeywordsAmbient temperatures Infrared Input optics NETD NEP Noise Optical radiation Radiance Radiation thermometer Responsivity Non-contact body temperature
Unable to display preview. Download preview PDF.
- 3.G.P. Eppeldauer, in NIST Technical Note 1438 (2001)Google Scholar
- 4.Eppeldauer, G.P.: J. Res. NIST 103, 153 (1998)Google Scholar
- 5.Rogalski, A., Chrzanowski, K.: Opto-Electron. Rev. 10, 111 (2002)Google Scholar
- 6.H.W. Yoon, M.C. Dopkiss, G.P. Eppeldauer, SPIE Proc. 6297, 629703-1–629703-10 (2006)Google Scholar