Research On Infrared Imaging Electronics Theory And Its Key Techniques

Infrared imaging technique has become one of the most promising high techniquesaround the developed countries today. Infrared imaging technique has achieved muchprogress during the past decade. But there are still some commonness problems, whichhave become the bottleneck of image quality improvement for infrared imaging system.The first commonness problem is that infrared imaging system possesses low temperatureresolution actually due to nonuniformity and non-effective pixels. Secondly, the size ofinfrared focal panel arrays (IRFPA) are limited and the detector pixel cannot be madesmall enough due to the material and producing process limitation. So that, the IRFPAspatial sampling frequency is lower than the Nyquist frequency of imaging systemnormally. This causes aliasing and the spatial resolution of infrared imaging system iscommonly low. Another commonness problem of infrared imaging is narrow grey rangeand low contrast. Above mentioned drawback of infrared imaging are waiting forbreakthrough from basic theory and principle analysis. Setting up exact theory model,which describes those problems more precise, and developing novel solution for infraredimaging inherent drawback are the motivation of this dissertation.This work studies on those commonness problems of infrared imaging. Focusing onthe imaging mechanism and inherent disadvantages of IRFPA detector, thephotoresponsive principle of IRFPA materials and detectors are analyzed. Several exacttheory models on processing electronics of infrared imaging are proposed in thisdissertation, namely, binary nonlinear nonuniformity theory model based on scene andsurrounding infrared radiation, non-effective pixel statistic character theory model andmicroscanning infrared imaging elimination aliasing theory model. Some novel processingelectronics algorithms and key techniques are present under the guidance of these theorymodels. The nonuniformity correction (NUC) based on surrounding temperaturecompensation not only improves the low correction precision of normal calibration-basedNUC caused by the nonlinearity of IRFPA responsive curve but also eliminates theinfluence of the detector responsive drift with Surrounding temperature. Non-effectivepixel detection based on multi-temperature matching improves the detection precision byavoiding misjudgment. Both the nonuniformity correction precision elevation and thenon-effective pixel accurate detection do benefits to the temperature resolutionimprovement of infrared imaging. Interpolation reconstruction infrared image based on microscanning eliminates aliasing resulting from sub-sampling of infrared imaging. Thismethod improves the spatial resolution of infrared imaging based on existing IRFPAtechnology. Self-adaptive histogram subsection modification can preserve the original graylevels mostly during extending the dynamic range of grey levels in infrared image.Self-adaptive infrared image contrast enhancement based on non-effective grey leveleliminating can enlarge the dynamic range of infrared image by grey histogram statisticand analysis. This method eliminates the grey levels, which possess zero possibility density,and then maps the effective grey levels to the whole grey range equality. Hence, thistechnique expands the dynamic range of infrared scene and enhances the contrast ofinfrared image without losing any grey levels and image detail. In order to measure keyparameters and evaluate the performance of IRFPA, characteristic parametersmeasurement and evaluation system for IRFPA is developed. An infrared imagingsimulation and demo system based on visible and multi-mode drive technology isestablished to simulate, validate, revise and finalize the design of processing electronicstechniques. It ensures designers evaluate infrared imaging effect directly.An integrated set of infrared imaging electronics theory models are set up in thisdissertation. Several novel techniques are present to elevate both temperature and spatialresolution and extend the dynamic range of infrared image. IRFPA charactistic parametermeasurement technology and system are developed. Infrared imaging electronicsprocessing algorithm simulation technology and demo system are studied and established.A comprehensive theoretical deduction and experimental test analysis is performed toprove the theory models and evaluate the novel electronics processing techniques.Based on above ground works, these theory models present in this dissertation arevalidated with plentiful experimental test, simulation ,and the chi-square test method ofdistribution hypothesis test theory in mathematical statistics. Furthermore, novel infraredimaging electronics processing method proposed in this dissertation are evaluated andcompared with existed method one by one. Both quantitative test and qualitativesimulation results show that these new technologies are excelled method in existence. Thehigh-quality processing abilities of presented key techniques are atso demonstrated throughapplication to real infrared imaging both cryogenically cooled and uncooled IRFPAsensors. The results are well pleasing. In conclusion, all experimental test, simulationcomparison and application results indicate that these key techniques deduced from noveltheory models proposed in this dissertation are effective to settle these commonnessdrawbacks of infrared imaging. Finally, avenues of future work are considered including possible infrared imaging electronics key technique extensions.This work smoothes the way to develop high-level infrared imaging electronicsmodules and advanced thermal imaging system in our country.