An acoustic thermometer for air refractive index estimation in long distance interferometric measurements

Pisani, Marco; Astrua, Milena; Zucco, Massimo

doi:10.1088/1681-7575/aa9a7a

Cited by 9 publications

(6 citation statements)

References 13 publications

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“…The CAT is based on an accurate measurement of the speed of sound, which extensively depends upon air temperature [ 18 ]. The principle has been already exploited in an experiment in the frame of a European research project [ 19 ] with the aim of improving the knowledge of the speed of sound in air.…”

Section: The Working Principlementioning

confidence: 99%

Non-Contact Thermometer for Improved Air Temperature Measurements

Pisani

Astrua

Merlone

2023

Sensors

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A compact thermometer for air temperature based on the measurement of the speed of sound was developed at INRIM. This paper focuses on the comparison of this instrument with platinum resistance thermometers in a climatic chamber over a temperature range (−30 ÷ +55) °C, relative humidity (10 ÷ 90)%rh, and irradiation (>1 kW/m2) values similar to those of surface atmospheric conditions. Overall uncertainty values of 0.2 °C over the range from −30 °C to +30 °C, and from 0.6 °C to +55 °C, were found. Moreover, the instrument proved to be immune to irradiation errors and free from the need for temperature calibration.

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Section: The Working Principlementioning

confidence: 99%

Non-Contact Thermometer for Improved Air Temperature Measurements

Pisani

Astrua

Merlone

2023

Sensors

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“…In our previous work [ 12 ], we presented a method based on the use of a continuous sound wave, and demonstrated its effectiveness and sensitivity with several experiments at different distances using acoustic waves at different frequencies.…”

Section: Introductionmentioning

confidence: 99%

Improved Acoustic Thermometry for Long-Distance Temperature Measurements

Pisani

Astrua

Zucco

2023

Sensors

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Accurate measurements of long distances (in the order of tens of meters or more) are necessary in manufacturing processes of large structures, as, for example, in the aerospace industry. In the most demanding applications, the goal is to achieve a relative accuracy of 10−7 in the measurement of distances (e.g., 1 µm over 10 m). This goal can be obtained with laser interferometers whose accuracy is based on knowledge of the speed of light, which, in turn, depends on the temperature of air. A thermometer based on the measurement of the speed of sound in air has been realized at INRIM. Its purpose is the measurement of the air temperature along the measurement path of the interferometer with an accuracy of 0.1 °C at distances up to 11 m. The paper describes the principle and the experimental setup of the acoustic thermometer and demonstrates its performance by comparison with calibrated reference platinum resistance thermometers. Furthermore, we demonstrate the potentiality of the method to measure the vertical temperature gradient, which is the main error source in triangulation measurements when using laser trackers.

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“…One is to measure the time required for an ultrasonic pulse to travel a given distance [19][20][21] and the other is to measure the resonant frequency (RF) of an acoustic resonator. The SOS is derived from its relationship with the RF and the cavity length of the resonator [22][23][24]. The above SOS-measuring methods are implemented exclusively using the speaker-microphone combination.…”

Section: Introductionmentioning

confidence: 99%

A speakerless acoustic thermometer

Xiong¹,

Yan²,

Cai³

et al. 2023

Meas. Sci. Technol.

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Existing acoustic thermometers are often implemented using speaker-microphone systems, which are power-consuming and inconvenient to operate. Here we demonstrate a simple speakerless acoustic thermometer, which is an acoustic Fabry-Perot resonator (AFPR) consisting of a tubular acoustic waveguide and a microphone whose diaphragm acts as a reflective surface of the AFPR. Theoretical analysis shows that the resonant frequency (fm) at a given mode order (m) for the AFPR is a linear function of m with the slope (Δf/Δm) depending on the ambient temperature. Therefore, when the linear relationship between fm and m for the AFPR is measured, the ambient temperature can be determined from its slope. The values of fm at different m can be easily obtained by using the AFPR to detect ambient white noise rather than the sound signal from a loudspeaker. The thermometric performance of the prepared AFPR was investigated in a range of temperatures from -17 °C to 60 °C. The measured temperatures show the mean absolute error below 0.9 °C relative to those simultaneously obtained with a commercial electronic thermometer. As experimentally demonstrated in this work, the AFPR can detect extremely weak white noise in the anechoic room and thus enables to accurate measure the ambient temperature there, attributable to its ultrahigh pressure sensitivity at each resonant frequency. The advantages of simple structure, low power consumption, convenient operation, and high detection accuracy offer the AFPR outstanding applicability for on-site temperature measurements in various environments.

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An acoustic thermometer for air refractive index estimation in long distance interferometric measurements

Cited by 9 publications

References 13 publications

Non-Contact Thermometer for Improved Air Temperature Measurements

Non-Contact Thermometer for Improved Air Temperature Measurements

Improved Acoustic Thermometry for Long-Distance Temperature Measurements

A speakerless acoustic thermometer

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