Optimization And Applied Research Of The Substrate-free FPA In IR Imaging

Except for military uses, uncooled infrared imaging (IR) technology is developing rapidly in recent years, and been widely used in industrial, medical, automotive, monitoring, etc. Our group designed and implemented a novel optical readout uncooled infrared imaging system. On the basis of previous studies, this manuscript does some optimization research on optical readout, the thermo-mechanical properties of the substrate-free focal plane arrays (FPA) under atmospheric conditions and the IR image restoration algorithms.First, this manuscript optimizes optical readout method, and finds that while considering the actual size of LED (light emitting diode) light source, it would cause analytical errors if simplify the LED light source to ideal point light source. Therefore, this manuscript establishes an area light source model to explain that the optical detection sensitivity is not reduced significantly with the FPA reflectors size (the ideal point source model affirms that it should be reduced linearly). Using the Fraunhofer diffraction theory the influence of the optical detection sensitivity on area light source is studied. The dependence of the optical detection sensitivity on light source radius and reflector length of the focal plane array (FPA) is found. And optimized design criteria for the size of light source, the length of the reflector, the focal length of lens and the wavelength of light source are proposed. According to theoretical analysis, the experimental verification is carried out.Based on the analysis of the key parameters in optical readout-edge position of the optimum filter, we find the relationship between the light intensity and the best edge position of the filter, and manufacture an adaptive knife-edge filtering system to solve the problem such as poor accuracy, difficult to quantify parameters, lack of reproducibility by manual regulation.Analysis the mechanical properties of the substrate-free FPA in atmospheric environment. According to the analogy of electrical models, we study the three heat exchange mechanism of the substrate-free FPA in atmosphere, and find that the substrate-free FPA still has certain infrared imaging capability, although the NETD (noise equivalent temperature difference) will be reduce a lot, but the substrate FPA is completely unable for IR imaging.Optimizes the optical readout IR images. Different from electrical readout, which has an integrated micro readout circuit under each unit, optical readout measures the reflective panel angle changes of the unit when they absorb infrared radiation. This is difficult to ensure that one FPA pixel is exactly corresponds with one pixel which is captured on CCD (charge coupled device), this manuscript studies the relations between them and establishes a criterion to estimate the one to one image reconstruction. And the thermal crosstalk of the substrate-free FPA is studied by FEM, it’s propose an image restoration algorithm of infrared target. By this means, we first develops the models to make the optical readout IR image and the electrical readout IR image as the same.At present, the NDT (Non Destructive Testing) is developing rapidly, the lock-in NDT does not require high frame rate and high detection accuracy, and will be widely used in engineering.this manuscript designs lock-in infrared devices for experiment uses, and achieves good results.