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Dual-Band Uncooled Infrared Microbolometer
Published in Krzysztof Iniewski, Smart Sensors for Industrial Applications, 2017
Qi Cheng, Mahmoud Almasri, Suzanne Paradis
A microbolometer is a thermal sensor whose resistance changes with temperature, associated with the absorption of IR radiation. Its performance is characterized by several figures of merit such as responsivity (Rv), TCR, detectivity (D*), and noise equivalent temperature difference (NETD) [34]. Responsivity is the output voltage divided by the input radiant power falling on the detector. It is given by () Rv=IbRηβG(1+ω2τth2)1/2
Temperature and heat flux measurements
Published in Stefano Discetti, Andrea Ianiro, Experimental Aerodynamics, 2017
Thermal detectors are based on thermoelectric effects, which have been previously treated when illustrating the working principles of thermocouples or resistance thermometers (see Sections 6.3 and 6.4). The incident radiation is absorbed by a heat capacitor, which electrical properties change proportionally to its temperature variation imposed by the absorbed energy. The output produced can be a differential voltage like in the case of thermopile sensors or a resistance variation. Common thermal detectors make use of microbolometers. These are very small sensors consisting of an absorptive element, such as a thin layer of metal, connected to a thermal reservoir at constant temperature. The radiation impinging on the absorptive element raises its temperature above that of the reservoir producing a change in the electrical resistance. The response of such devices is proportional to the ratio between the heat capacity of the absorber and the absorber–reservoir thermal conductivity. Modern microbolometers enable acquisition frequencies up to 60 Hz with good thermal resolutions. Materials used for manufacturing thermal detectors include amorphous silicon and vanadium oxide (V2O5).
Thermal and mechanics research on a 15μm umbrella-like structure microbolometer
Published in Ai Sheng, Energy, Environment and Green Building Materials, 2015
Uncooled microbolometer is widely used in civil and military applications due to its room temperature operation capability, small size, low power dissipation, light weight, and superior reliability [1,2,3]. The detection principle of microbolometer pixel is based on the absorption of infrared radiation, which changes the temperature of the IR-sensitive membrane. The change of electrical resistance due to this temperature change can be read out by an integrated circuit of microbolometer [2].
Feature analysis for drowsiness detection based on facial skin temperature using variational autoencoder : a preliminary study
Published in Quantitative InfraRed Thermography Journal, 2022
A. Masaki, K. Nagumo, K. Oiwa, A. Nozawa
The measured physiological indices were the following: facial skin temperature (FST), electroencephalograms (EEG) as brainwaves. The bioinstrumentation system consisted of an infrared thermography device (A-615, FLIR, America) and wireless biological measuring equipment (Polymate Mini AP108, TEAC Co., Japan). The infrared thermography device was set at a distance 100 cm from the face. Thermal images were created at 1-s sampling intervals. The size of each thermal image was 640 × 480 pixels, and the temperature resolution was less than 0.1°C. The infrared emissivity of the skin was ε = 0.98. The infrared thermography image sensor used in the experiment was an uncooled microbolometer type. The spectral wavelength is 7.5 14 μm. The infrared thermography camera was turned on at least 20 minutes before the start of the experiment to ensure stability. The experiment was started after confirming that the measured temperature values did not deviate from the general skin temperature. The wireless biological measuring equipment recorded the EEG with a sampling frequency of 500 Hz. To evaluate relative an alpha waves, EEG was recorded by a referential electrode derivation method. The EEG electrode was fixed at parietal (Pz) positions according to the international 10–20 system. The right ear lobe (A2) was used as a reference. Before data acquisition, the contact impedance between the EEG electrodes and scalp was calibrated to be less than 10 kΩ. Figure 1. shows the experimental image.
Effectiveness of phased array focused ultrasound and active infrared thermography methods as a nondestructive testing of Ni-WC coating adhesion
Published in Nondestructive Testing and Evaluation, 2019
R. Rachidi, B. Elkihel, F. Delaunois, D. Deschuyteneer
Figure 5 shows the set-up used for thermography tests using thermal stimulation by a lamp. It consists of a FLIR T440 infrared camera used to collect data. This device consists of an uncooled microbolometer detector of 320 × 240 pixels, sensitive in the infrared spectral band of 7.5–13 μm (far infrared). Some important characteristics of the FLIR T440 infrared camera are summarised in Table 1. Two lamps serving as heating means are positioned at about 1 m and oriented at an angle of 30° to the normal of the coating surface, in order to obtain the uniform distribution of heat flux on the surface. The infrared camera is positioned at a distance, which allows us to focus and take pictures of the entire sample. The obtained information is stored in a computer.