An empirical method for improving accuracy of human eye temperature measured by uncooled infrared thermal imager

In order to reduce the temperature measurement error with the uncooled infrared thermal imager, experiments were conducted to evaluate the effects of environment temperature and measurement distance on the measurement error of human eye temperature. First, the forehead temperature was used as an intermediate variable to obtain the actual temperature of human eyes. Then, the effects of environment temperature and measurement distance on the temperature measurement were separately analyzed. Finally, an empirical model was established to correlate actual eye temperature with the measured temperature, environment temperature, and measurement distance. To verify the formula, three different environment temperatures were tested at different distances. The measurement errors were substantially reduced using the empirical model for temperature correction. The results show that this method can effectively improve the accuracy of temperature measurement using the infrared thermal imager.

CVD preparation of vertical graphene nanowalls/VO_(2)(B)composite films with superior thermal sensitivity in uncooled infrared detector

Vanadium dioxide with superior thermal sensitivity is one of the most preferred materials used in microbolometer,and the B phase of VO_(2) is particularly prominent.However,conventional VO_(2)(B)undergoes low temperature-coefficient of resistance(TCR)values and large resistances.In this paper,simple controllable composite films of vertical graphene nanowalls/VO_(2)(B)(i.e.,VGNWs/VO_(2)(B))with a suitable square resistance(12.98 kU)and a better temperature-coefficient of resistance(TCR)(-3.2%/K)were prepared via low pressure chemical vapor deposition.The VGNWs can provide a fast channel for electron transport and enhance the conductivity of VO_(2)(B).This preparation method can provide a low cost,facile and simple pathway for the design and fabrication of high performance VO_(2)(B)thin films with superior electrical properties for its application in uncooled infrared detectors.

A low-cost infrared absorbing structure for an uncooled infrared detector in a standard CMOS process

This paper introduces a low-cost infrared absorbing structure for an uncooled infrared detector in a standard 0.5 m CMOS technology and post-CMOS process. The infrared absorbing structure can be created by etching the surface sacrificial layer after the CMOS fabrication, without any additional lithography and deposition procedures. An uncooled infrared microbolometer is fabricated with the proposed infrared absorbing structure.The microbolometer has a size of 6565 m2and a fill factor of 37.8%. The thermal conductance of the microbolometer is calculated as 1.3310 5W/K from the measured response to different heating currents. The fabricated microbolometer is irradiated by an infrared laser, which is modulated by a mechanical chopper in a frequency range of 10–800 Hz. Measurements show that the thermal time constant is 0.995 ms and the thermal mass is 1.3210 8J/K. The responsivity of the microbolometer is about 3.03104V/W at 10 Hz and the calculated detectivity is 1.4108cm Hz1=2/W.

Surface plasmon-enhanced dual-band infrared absorber for VO_x-based microbolometer application

We propose a periodic structure as an extra absorption layer（i.e., absorber） based on surface plasmon resonance effects, enhancing dual-band absorption in both middle wavelength infrared（MWIR） and long wavelength infrared（LWIR）regions. Periodic gold disks are selectively patterned onto the top layer of suspended SiN/VO_2/SiN sandwich-structure.We employ the finite element method to model this structure in COMSOL Multiphysics including a proposed method of modulating the absorption peak. Simulation results show that the absorber has two absorption peaks at wavelengths λ =4.8 μm and λ = 9 μm with the absorption magnitudes more than 0.98 and 0.94 in MWIR and LWIR regions, respectively. In addition, the absorber achieves broad spectrum absorption in LWIR region, in the meanwhile, tunable dual-band absorption peaks can be achieved by variable heights of cavity as well as diameters and periodicity of disk. Thus, this designed absorber can be a good candidate for enhancing the performance of dual band uncooled infrared detector, furthermore, the manufacturing process of cavity can be easily simplified so that the reliability of such devices can be improved.

On the MOSFET-Based Temperature Sensitive Element for Bolometer Application

This paper focuses on the study of thermal performances of MOS （metal-oxide-semiconductor） transistors for uncooled infrared bolometer applications. Such devices can be used in various applications both military and civil, such as defence and security, medical applications, industrial surveillance, etc. Series of measurements were conducted to obtain TCC （temperature coefficient of current） versus gate voltage and temperature curves. The TCC is a figure of merit for a device used as the sensitive element in a bolometer that represents its sensitivity to temperature and as such is a good indicator of the detector attainable performance. The measurements were confronted to Atlas simulations, and showed that in the subthreshold region the TCC ranges from 4%/K all the way to 9%/K which represents a great improvement compared to state of the art thermistor bolometers. Analytic expressions of the TCC are also derived from current equations of the MOSFET （MOS field effect transistor） drain current to help understanding the effect of drain to source voltage, mobility, temperature and threshold voltage sensibility to temperature, in all three operation modes of the transistor （subthreshold, ohmic and saturation）. It was also determined that gate length does not have an influence on the TCC until short channel effects are factored in.