Design Of Far-infrared Microscopic Imaging Optical System And Fabrication Of Ge-based BIB Detector

With the development of infrared technology,infrared detecting materials,devices,and corresponding imaging systems have made significant advance.For example,in the infrared region the working band of a detector has been expanded from its original short and middle wave bands to today's long wave and even far infrared wave band.Facing to the urgent demand to far infrared detectors and microscopic imaging optical systems(FIMIOS)in the areas of infrared astrophysics,dark matter and energy detecting,and extraterrestrial life seeking,major works of the thesis involved the simulation of the FIMIOS,as well as the fabrication and performance characterization of the Ge:B blocking impurity band(BIB)long wavelength infrared detectors.In this thesis,we briefly described the developing history and present research status of both the FIMIOS and BIB detectors,the aim and significance of our work,the design principle of the far infrared optical systems,together with the structure and operating mechanism of the BIB detectors.As to the FIMIOS the emphasis was put on the design route,on evaluation of the imaging quality,and on both the origin and inhibition of the stray light.For the Ge:B BIB detectors its preparation and performance characterization were mainly introduced.Both the simulation and experimental data were carefully analyzed and discussed.The obtained chief results are as following:1.In order to make the cooled staring focal plane array detectors,operating in the50?70?m wave band and containing 64x64 pixels(each unit exhibiting a size of120×120?m²),get enough far infrared radiation energy,a transmission type of FIMIOS was proposed.This system includes a diaphragm with a numerical aperture of 0.25 and an objective lens comprising of five piece of high resistance silicon lenses.By optimizing the structural parameters and the material property parameters,a FIMIOS was designed.This FIMIOS has a lateral magnification of 10,a spacial resolution of 0.2mm,and operates in the central wavelength of 61?m.2.By analyzing system's surrounding circle energy diagram,spot array diagram,field curvature,distortion,chromatic aberration and modulation transfer function(MTF),it was found that when the central wavelength,focal length,numerical aperture,effective magnification and spatial resolution of the FIMIOS designed were61?m,14 mm,0.25,10 and 0.2 mm respectively,the MTF value was 0.31 at the characteristic frequency of 5 lp·mm^-1,the energy concentration degree exceeded 80%for each pixel,over 75%far infrared radiation energy could be focused on the light-sensitive element of the BIB detector,and a clear object image was formed.In addition,we discovered that the cold infrared stray light mainly stem from the optical elements'reflection to the cooler's radiation.The cold stray light could be significantly decreased and the quality of a picture could be markly improved through coating special optical thin films on the optical elements'surfaces.3.According to the device's architecture designed previously,a series of Ge:B BIB detectors were made by the ion-implantation process and lithography.The testing results shown that the single Ge:B BIB detector at 3 K was on the order of magnitude of 10^-10A,meaning that a high ratio of signal to noise and large blackbody detectivity might be realized for these detectors.