Abstract
The infrared detector is the most important component within any radiation thermometry-based system, with its choice determining the wavelength, response time and, ultimately, the temperature measurement capabilities of the instrument. To improve upon the existing generation of radiation thermometers, more sensitive detector technologies are required. In this work, we demonstrate a direct comparison between an indium gallium arsenide (InGaAs) photodiode and an InGaAs avalanche photodiode (APD) for 1.6 µm radiation thermometry. The high internal gain of the InGaAs APD increases the sensitivity of the radiation thermometer, enabling the measurement of a target temperature more than 50 °C lower than is typical with commercially available InGaAs photodiode thermometers. The more sensitive InGaAs APD provides faster response time measurements, hence improving the thermometer’s temporal resolution. Finally, the InGaAs APD is shown to produce a quantitative thermal image with lower measured temperature fluctuation across the scene when incorporated within a highly aperture limited scanning system.
Highlights
Radiation thermometers operating at 1.6 μm are used for general purpose non-contact temperature measurement applications
We demonstrate an indium gallium arsenide (InGaAs) avalanche photodiode (APD) as a viable detector technology for noncontact temperature measurement in direct comparison with
We have demonstrated an InGaAs APD to be a more sensitive detector technology for use within 1.6 μm radiation thermometry-based instrumentation
Summary
Radiation thermometers operating at 1.6 μm are used for general purpose non-contact temperature measurement applications. Its increased sensitivity should lead to the measurement of lower target temperatures, improve the signal-to-noise ratio (SNR) of inherently aperture limited instrumentation and enable faster speed measurements. The latter is especially important for the development of instruments capable of measuring fast transitions whilst still maintaining good noise performance within the temperature measurement. We have previously demonstrated a Si APD for 1 μm radiation thermometry in comparison with a Si photodiode, demonstrating that the Si APD can measure a lower minimum target temperature [11, 12] It would, be reasonable to expect the InGaAs APD to offer improvement in performance over an InGaAs photodiode. The more sensitive InGaAs APD is shown to measure a target temperature more than 50 °C lower than an InGaAs photodiode, enable faster speed temperature measurements and produce a quantitative thermal image with lower fluctuation in the measured temperature when operated within a highly aperture limited scanning system
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