Optical and Electrical Characterizations of Uncooled Bolometers Based on LSMO Thin Films

Nascimento, Vanuza Marques Do; Silva, Mario Eduardo B.G.N.; Liu, Shuang; Manera, Leandro Tiago; Méchin, Laurence; Guillet, Bruno

doi:10.3390/proceedings1040634

Cited by 1 publication

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References 14 publications

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“…Assembling a set of microbolometers into an array at the focal plane of a thermal camera lens forms a focal plane array (FPA), which can be heated by the infrared radiation focused through the lens [5,6]. The electrical Drones 2022, 6, 394 2 of 20 resistance of each individual microbolometer is dependent on its temperature [7] and varies proportionally to the incident infrared radiation. A readout circuitry (ROIC) reads the resistance of the microbolometers, and thus provides the temperature information of a scene observed by the camera [8].…”

Section: Introductionmentioning

confidence: 99%

A Case Study of Vignetting Nonuniformity in UAV-Based Uncooled Thermal Cameras

Yuan¹,

Hua

2022

Drones

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Uncooled thermal cameras have been employed as common UAV payloads for aerial temperature surveillance in recent years. Due to the lack of internal cooling systems, such cameras often suffer from thermal-drift-induced nonuniformity or vignetting despite having built-in mechanisms to minimize the noise. The current study examined a UAV-based uncooled thermal camera vignetting regarding camera warmup time, ambient temperature, and wind speed and direction, and proposed a simple calibration-based vignetting migration method. The experiments suggested that the camera needed to undergo a warmup period to achieve stabilized performance. The required warmup duration ranged from 20 to 40 min depending on ambient temperature. Camera vignetting severity increased with camera warmup time, decreasing ambient temperature, and wind presence, while wind speed and direction did not make a difference to camera vignetting during the experiments. Utilizing a single image of a customized calibration target, we were able to mitigate vignetting of outdoor images captured in a 30 min duration by approximately 70% to 80% in terms of the intra-image pixel standard deviation (IISD) and 75% in terms of the pixel-wise mean (PWMN) range. The results indicated that outdoor environmental conditions such as air temperature and wind speed during short UAV flights might only minimally influence the thermal camera vignetting severity and pattern. Nonetheless, frequent external shutter-based corrections and considering the camera nonlinear temperature response in future studies have the potential to further improve vignetting correction efficacy for large scene temperature ranges.

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